[105512] in North American Network Operators' Group
Re: Possible explanations for a large hop in latency
daemon@ATHENA.MIT.EDU (John T. Yocum)
Thu Jun 26 20:04:08 2008
Date: Thu, 26 Jun 2008 17:03:46 -0700
From: "John T. Yocum" <john@fluidhosting.com>
To: frnkblk@iname.com
In-Reply-To: <!&!AAAAAAAAAAAuAAAAAAAAAKTyXRN5/+lGvU59a+P7CFMBAN6gY+ZG84BMpVQcAbDh1IQAAAATbSgAABAAAAAIgYgvPVlNSJZFmGlF6V4QAQAAAAA=@iname.com>
Cc: nanog list <nanog@merit.edu>
Errors-To: nanog-bounces@nanog.org
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
>
>
