[105501] in North American Network Operators' Group
Possible explanations for a large hop in latency
daemon@ATHENA.MIT.EDU (Frank Bulk)
Thu Jun 26 18:51:54 2008
From: "Frank Bulk" <frnkblk@iname.com>
To: "nanog list" <nanog@merit.edu>
Date: Thu, 26 Jun 2008 17:51:42 -0500
Reply-To: frnkblk@iname.com
Errors-To: nanog-bounces@nanog.org
Our upstream provider has a connection to AT&T (12.88.71.13) where I
relatively consistently measure with a RTT of 15 msec, but the next hop
(12.122.112.22) comes in with a RTT of 85 msec. Unless AT&T is sending that
traffic over a cable modem or to Europe and back, I can't see a reason why
there is a consistent ~70 msec jump in RTT. Hops farther along the route
are just a few msec more each hop, so it doesn't appear that 12.122.112.22
has some kind of ICMP rate-limiting.
Is this a real performance issue, or is there some logical explanation?
Frank
