Possible explanations for a large hop in latency

Thu Jun 26 23:58:53 UTC 2008

Deep Packet Inspection engine delay. <G>

On Jun 26, 2008, at 6:51 PM, 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
>
>

James R. Cutler
james.cutler at consultant.com