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[virendra.rode () gmail com: [Outages] Theoretical vs real-world speed limit of Ping]
From: ge () linuxbox org
Date: Sun, 3 Jun 2007 05:32:20 -0500
----- Forwarded message from virendra rode // <virendra.rode () gmail com> ----- X-YMail-OSG: qjafWdEVM1mxBrVAofd68nzg.HZGcD2L8xdJlcrwxL4c_nadnQxhUibcwWN3BHegQYFUcdvaaRMWJgnixecsV86NUXabN_P2Fq4e From: virendra rode // <virendra.rode () gmail com> To: outages () isotf org X-Enigmail-Version: 0.94.0.0 Subject: [Outages] Theoretical vs real-world speed limit of Ping X-BeenThere: outages () isotf org X-Mailman-Version: 2.1.9rc1 Reply-To: virendra.rode () gmail com List-Id: "Outages \(planned & unplanned\) Reporting" <outages.isotf.org> List-Unsubscribe: <http://isotf.org/mailman/listinfo/outages>, <mailto:outages-request () isotf org?subject=unsubscribe> List-Archive: <http://isotf.org/pipermail/outages> List-Post: <mailto:outages () isotf org> List-Help: <mailto:outages-request () isotf org?subject=help> List-Subscribe: <http://isotf.org/mailman/listinfo/outages>, <mailto:outages-request () isotf org?subject=subscribe> X-Greylist: Default is to whitelist mail, not delayed by milter-greylist-1.7.5 (linuxbox.org [24.155.83.21]); Sun, 03 Jun 2007 01:26:12 -0500 (CDT) X-Spam-Status: No, score=-102.6 required=20.0 tests=AWL,BAYES_00, USER_IN_ALL_SPAM_TO autolearn=ham version=3.0.3 X-Spam-Checker-Version: SpamAssassin 3.0.3 (2005-04-27) on linuxbox.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I thought some of you might be interested in this stats. credit: pingdom Theoretical response time limits of Ping So, if we assume that a ?ping? travels with the speed of light, which are the best possible response times we can get? 10 km -> 0,067 milliseconds 100 km -> 0,67 milliseconds 1,000 km -> 6,7 milliseconds 10,000 km -> 67 milliseconds (Note that Ping shows the time for a roundtrip, i.e. 2 x the distance.) Pinging between Europe and USA The distance between New York and Paris is 5,839 km. For light to travel from New York to Paris and then back again would take 40 milliseconds. Maximum distance between two places on Earth If you choose the shortest route, the maximum distance between two locations will never be more than halfway around the planet. Halfway around Earth is about 20,000 km. Considering that Ping goes to a destination and then back again, the packet sent by Ping would travel 40,000 km, the equivalent of a trip around Earth. That is 133 milliseconds. Anyone who has tried to ping various servers across the world will know that this is a way better response time than what you can realistically get. So why is ping so slow? Why Ping is slower in the real world The examples above take place under ideal conditions that don?t exist in the real world. 1. The actual distance traveled will be longer, more like zig zag than a straight line. 2. Repeaters, switches and routers will slow down transfer speeds. The more equipment the signal has to pass through (for example routers), the longer it will take to reach its target. 3. The actual speed of the signal will never quite match the speed of light. Even with fiber optics (glass) the speed of light is about 30% slower than through vacuum or air, and most of the distance covered will be through fiber. 4. A beam of light bounces around like a pinball when it travels along the thin (admittedly extremely thin) fiber, and that will of course make the distance traveled even longer. With all this in mind, you should probably double the ?ideal? response times shown above for a more realistic target to aim at. It?s useful to know when there is room to push for better network performance, and when the actual physical limits set in. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGYl7tpbZvCIJx1bcRAm84AJwMc7QLMEoNu8KKj5nO0YWIJLfJuQCg4eNe 8xugB0Mk7w+fj4+QGgFBDn8= =PNc8 -----END PGP SIGNATURE----- _______________________________________________ Outages mailing list Outages () isotf org http://isotf.org/mailman/listinfo/outages ----- End forwarded message ----- -- -- "beepbeep it, i leave work, stop reading sec lists and im still hearing gadi" - HD Moore to Gadi Evron on IM, on Gadi's interview on npr, March 2007. _______________________________________________ Fun and Misc security discussion for OT posts. https://linuxbox.org/cgi-bin/mailman/listinfo/funsec Note: funsec is a public and open mailing list.
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- [virendra.rode () gmail com: [Outages] Theoretical vs real-world speed limit of Ping] ge (Jun 03)