nanog mailing list archives
Re: ATM (was Re: too many routes)
From: Richard Irving <rirving () onecall net>
Date: Fri, 12 Sep 1997 09:57:53 -0500
Nathan Stratton wrote:
On Thu, 11 Sep 1997, Vadim Antonov wrote:Quote from Jim Steinhardt's <jsteinha () cisco com> personal message:a) light is slower in dense mediaThe index of refraction of glass is 1.5 vs 1.0 for a vacuum. Hence, the speed of light in glass is 2 * 10 **8 m/s.That gives 60 ms RTT on 4000 mile line. Case closed.Yep, but you also need to add a few ms for electronics in that 4000 mile line.
My original point. (Concerning latency)
We tend to see around 64 - 65 ms delay between our DCA and PAL routers. rt1.DCA.netrail.net# ping rt1.PAL ICMP ECHO rt1.PAL.netrail.net (205.215.45.33): 56 data bytes 64 bytes from 205.215.45.33: icmp_seq=0 ttl=255 time=65.764 ms 64 bytes from 205.215.45.33: icmp_seq=1 ttl=255 time=64.851 ms 64 bytes from 205.215.45.33: icmp_seq=2 ttl=255 time=65.053 ms 64 bytes from 205.215.45.33: icmp_seq=3 ttl=255 time=64.994 ms ^C
How may hops is that ping ? I am curious, this is interesting. (Even if I did get mail bombed by responses...... ;) You realize we need to be comparing a *series* of routers, vs a *series* of ATM switches. (this is the real world, and we are modelling delivery to anywhere, not just 1 hop across the continent.) It would be interesting to see someone set up a performance test. Latency/Variability with no hops, Latency/Variability with 1 router vs 1 switch Latency/Variability with 2 routers vs 2 switches Up to about 10. I wonder what that curve would look like ? Media would have to be consistent in size (ie DS3, all the way through) Interesting , no ?
--- rt1.PAL.netrail.net ICMP ECHO statistics --- 4 packets transmitted, 4 packets received, 0% packet loss round-trip min/avg/max = 64.851/65.160/65.764 ms rt1.DCA.netrail.net# Nathan Stratton President, CTO, NetRail,Inc. ------------------------------------------------------------------------ Phone (888)NetRail NetRail, Inc. Fax (404)522-1939 230 Peachtree Suite 500 WWW http://www.netrail.net/ Atlanta, GA 30303 ------------------------------------------------------------------------ "No king is saved by the size of his army; no warrior escapes by his great strength. - Psalm 33:16
Richard
Current thread:
- Re: Physical transport media, (continued)
- Re: Physical transport media Tim Gibson (Sep 16)
- Re: Physical transport media Michael Dillon (Sep 16)
- Re: Physical transport media Rob Barron (Sep 16)
- Message not available
- Re: Physical transport media Jay R. Ashworth (Sep 16)
- Message not available
- Re: NANOG-PHYSICS (was Re: ATM (was Re: too many routes)) Geoff Huston (Sep 15)
- Re: ATM (was Re: too many routes) Randy Bush (Sep 18)
- Re: ATM (was Re: too many routes) Tim Pozar (Sep 15)
- Re: ATM (was Re: too many routes) Sean M. Doran (Sep 11)
- Re: ATM (was Re: too many routes) Vadim Antonov (Sep 11)
- Re: ATM (was Re: too many routes) Nathan Stratton (Sep 12)
- Re: ATM (was Re: too many routes) Richard Irving (Sep 12)
- Re: ATM (was Re: too many routes) Vadim Antonov (Sep 12)
- Re: ATM (was Re: too many routes) Richard Irving (Sep 12)
- I found the missing 30 milliseconds! Kent W. England (Sep 16)
- Re: I found the missing 30 milliseconds! Craig A. Huegen (Sep 16)
- Message not available
- Re: I found the missing 30 milliseconds! Jay R. Ashworth (Sep 16)
- Re: I found the missing 30 milliseconds! Taner Halicioglu (Sep 16)
- Re: I found the missing 30 milliseconds! Kent W. England (Sep 17)
- Re: ATM (was Re: too many routes) Robert E. Seastrom (Sep 12)
- Re: ATM (was Re: too many routes) Michael Dillon (Sep 12)
- Re: ATM (was Re: too many routes) Dorian R. Kim (Sep 12)