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Traceroute through MPLS cloud

Traceroute through MPLS cloud

LEM
New Contributor
Traceroute through MPLS cloud.I have a simple demo stand for MP-BG. Here is how it looks:
CE1-PE1-PE2-CE2

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.
17 REPLIES 17

LEM
New Contributor
Nikolay, thanks!

Necheporenko__N
Contributor II
Hello LEM,

This are known issues documented under
CR xos0051847 - OAM: Traceroute via MPLS path does not display the intermediate hops
and
CR xos0016965 - EXOS kernel does not properly send back ICMP responses.

Currently we have no target release dates for them.

Best Regards,
Nikolay

LEM
New Contributor
Well, i will try to open a case in TAC.
Thanks!

Stephane_Grosj1
Contributor II
Hi, That would require to open a case imho, as I'm wondering if this is an ICMP bug or not. The documentation would also need to be checked as it might refer to a previous gen of ASIC. I'm not sure of it, so investigation would be beneficial. My 2 cents.
GTM-P2G8KFN