nanog mailing list archives

Re: Possible explanations for a large hop in latency


From: "John T. Yocum" <john () fluidhosting com>
Date: Thu, 26 Jun 2008 17:03:46 -0700

When I asked ATT about the sudden latency jump I see in traceroutes, they told me it was due to how their MPLS network is setup.

--John

Frank Bulk wrote:
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





Current thread: