question concerning traceroute?

Thu Oct 17 14:45:39 UTC 2002

> I am trying to troubleshoot a latency issue for some of our networks,
> and was wondering about this.Knowing that routing isn't always
> symmetrical, is it possible for a traceroute to traverse a different
> reverse path, than the path that it took to get there?  

Traceroute sends UDP datagrams and receives ICMP datagrams in order to
show you what it shows you. It is possible for the ICMP datagrams to
return via a different path than the UDP datagrams took outbound (it
is also possible that they will not return).

> .or will it provide a trace of the path the packet took to reach the
> destination?

This is not the "or" case of the question you asked previously.

Traceroute will display the path that the UDP datagrams took to get to
the destination you specified. No information will be presented about
the return path that the ICMP datagrams took.

> According to definition, is should take the same path

This is not a correct assertion.

> but are there any other cases that I should be aware of?

The traceroute man page lists a few.

Stephen