On 2014-09-04 19:16, Aaron wrote:
In my network traceroute works fine for on-net (known) subnets. I can
see
the mpls lsr P hops.
But when I traceroute to internet destinations off-net (unknown)
subnets and
my packets follow default routing, I do not see my mpls lsr P hops.
What is the deal with traceroute being broken when following the
default
route ?
Just a guess:
Remember that the ICMP ttl-exceeded packet gets switched to the LSPs
tail-
end LER/PE where IP processing can happen, but for a learned
default-route
will most probably not occur and instead packets get MPLS-switched to
the
default-routes l2adjacency on your ISP-facing LER/PE directly (without
consulting the VRF). Hence my guess is that your ISPs router doesn't
want
to route the ttl-exceeded packets back to you (maybe URPF ingress ->
you
have private linknetworks sourcing the ICMP-ttl's?).
Cheers
Chris
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