Possible explanations for a large hop in latency

Sam Stickland sam_mailinglists at spacething.org
Wed Jul 2 00:07:23 UTC 2008

Even if they are decrementing TTL inside of their MPLS core, the TTL 
expired message still has to traverse the entire MPLS LSP (tunnel), so 
the latency reported for each "hop" is in fact the latency of the last 
hop in the MPLS network. Always.


Robert Richardson wrote:
> They probably don't propagate TTL w/in their MPLS core.  Depending on how
> they have MPLS implemented, you may only see 2 hops on the network; the
> ingress and egress routers.  If the ingress router was in NYC and the egress
> in Seattle, you could understandably expect a large jump in RTT.
> Not an ATT customer but do know other providers run their MPLS core's this
> way...
> -Robert
> On Thu, Jun 26, 2008 at 6:09 PM, John T. Yocum <john at fluidhosting.com>
> wrote:

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