Possible explanations for a large hop in latency

John T. Yocum john at fluidhosting.com
Fri Jun 27 00:03:46 UTC 2008

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.


Frank Bulk wrote:
> Our upstream provider has a connection to AT&T ( where I
> relatively consistently measure with a RTT of 15 msec, but the next hop
> ( 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
> has some kind of ICMP rate-limiting.
> Is this a real performance issue, or is there some logical explanation?
> Frank

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