nanog mailing list archives
Re: Learning about the internet
From: William Herrin <bill () herrin us>
Date: Mon, 3 Nov 2014 17:14:45 -0500
On Mon, Nov 3, 2014 at 4:15 PM, Paige Thompson <paigeadele () gmail com> wrote:
I would be able to find an answer as to why the latency between here in greece and Los Angeles is roughly ~250ms.
10.|-- be2171.mpd22.dca01.atlas.cogentco.com 0.0% 10 62.6 62.7 62.4 63.3 0.0 11.|-- be2112.ccr41.iad02.atlas.cogentco.com 0.0% 10 155.5 155.8 155.5 156.1 0.0
^^ There's the largest part part of your answer. IAD and DCA are both Northern VA airports; there should be perhaps 4ms of latency between these locations. A more smug answer is, "Cogent." Google "cogent congestion," "Cogent peering," and similar search terms. Other parts of the answer include: 1. The routers are mostly doing store and forward which means each must receive your entire packet before it can forward it onward to the next router. This will take more or less time depending on the link speed. 2. There are layer 2 devices doing the same thing in between some of the routers. Layer 2 is invisible to the layer 3 traceroute. There may also be MPLS systems in there with the same impact. 3. Greece and LA are more than 11,000 km apart as the crow flies. This means round-trip packets travel something like 25,000 km. There is some signal propagation delay involved. U.S. East Coast to Hawaii (about 80% of that distance) is typically 120 ms. Regards, Bill Herrin -- William Herrin ................ herrin () dirtside com bill () herrin us Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/> May I solve your unusual networking challenges?
Current thread:
- Learning about the internet Paige Thompson (Nov 03)
- Re: Learning about the internet joel jaeggli (Nov 03)
- Re: Learning about the internet William Herrin (Nov 03)
- Re: Learning about the internet Brian Loveland (Nov 03)
- RE: Learning about the internet Dustin Melancon (Nov 03)
- Re: Learning about the internet Brian Loveland (Nov 03)
- Re: Learning about the internet Dustin Melancon (Nov 03)