[c-nsp] traceroute shows mpls labels...how?

sthaug at nethelp.no sthaug at nethelp.no
Wed Aug 22 17:02:38 EDT 2012

> That's what I was looking for.  So is it a part of the mpls lsr's icmp
> implementation that would allow those icmp extensions to carry and send that
> info or the traceing device (windows) or both?  In other words, I wonder if
> the windows device actually is rcv'ing the icmp extended packets carrying
> that mpls label info BUT the tracert windows application just isn't smart
> enough to render it on the cli output..

Since I get MPLS labels shown using "ntraceroute" (Nanog traceroute)
on my FreeBSD box, it's pretty clear that other hosts also receive
the MPLS label info (assuming it is transmitted by routers on the
way). Whether they can *use* the label info is another question.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no

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