Possible explanations for a large hop in latency

Frank Bulk frnkblk at iname.com
Thu Jun 26 17:51:42 CDT 2008


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





More information about the NANOG mailing list