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Very weird traceroute problem!?!?! (Hair about to be pulled!)

Hi everyone,

A customer of mine has a problem when she traceroutes from a management server.

She goes through a router which connects to a peering lan for BGP. The router peers with around 20 other routers on this LAN.

Basically the traceroute goes:

Server - Router A - Customer A - Customer B

It should go

Server - Router A - Customer A

In ip it is: (IP's made up!) - - -

Now it gets worse:

When she does an extended traceroute from Router A it works fine to everywhere! It also works fine if she does a traceroute from the server to! All other addresses on the lan report this problem apart from 2 others and

Even worse when she does a recorder ping the packets hits the correct ip first time the same when she does a recorder traceroute.

We have no visibility of the other peering routers so I cannot see the config but I cannot understand why a packet destined for one ip on a lan would be responded to by another and then finally passed on to its final destination. I can't see how it can be a routing issue because an extended traceroute from the lan the server is on works fine?????

Any suggestions appreciated,

New Member

Re: Very weird traceroute problem!?!?! (Hair about to be pulled!

The routing tables are going to tell the story on this one. What I would do, is get a copy of the routing table for all hops involved. At the very least the "sh ip route x.x.x.x" for the source and destinations involved. Using this you should be able to tell where the breakdown is.


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