[105520] in North American Network Operators' Group
RE: Possible explanations for a large hop in latency
daemon@ATHENA.MIT.EDU (Frank Bulk - iNAME)
Thu Jun 26 20:54:52 2008
From: "Frank Bulk - iNAME" <frnkblk@iname.com>
To: "'John T. Yocum'" <john@fluidhosting.com>
In-Reply-To: <48642E62.70206@fluidhosting.com>
Date: Thu, 26 Jun 2008 19:54:42 -0500
Cc: nanog list <nanog@merit.edu>
Reply-To: frnkblk@iname.com
Errors-To: nanog-bounces@nanog.org
Did that satisfy you? I guess with MPLS they could tag the traffic and send
it around the country twice and I wouldn't see it at L3.
Frank
-----Original Message-----
From: John T. Yocum [mailto:john@fluidhosting.com]
Sent: Thursday, June 26, 2008 7:04 PM
To: frnkblk@iname.com
Cc: nanog list
Subject: Re: Possible explanations for a large hop in latency
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
>
>
