Traceroute through MPLS cloud.I have a simple demo stand for MP-BG. Here is how it looks:
We have BGP peering between CE and PE routers and OSPF, MPLS, MP-BGP inside provider cloud.
Both CE routers successfuly exhange routes. CE1 can see CE2 routes and vice versa.
I try to make trace from CE1 (192.168.101./0 ) to CE2 (192.168.102.0/24). Here is an output:
SW1.8 # traceroute 192.168.102.9 from 192.168.101.1
traceroute to 192.168.102.9, 30 hops max
1 172.16.13.3 1 ms 4 ms 13 ms
2 * * *
3 172.16.49.9 1 ms * 10 ms
Why do we have this string in output?
2 * * *
Here is a quoute from user guide:
In this mode, the MPLS TTL is independent of the IP TTL. The MPLS TTL is set to 255 on all packets
originated by the switch and on all packets that enter a pseudowire.
So, we should not see mpls path in trace.