Traceroute through MPLS cloud

[LEM]

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.

[Prashanth_KG]

Hi,

Between the PE devices, do we have pseudowire for the transport of the CE traffic or we have MPLS routing in place?

Another possible reason in addition to Erik's suggestion:
If router does not respond within a timeout then traceroute prints an asterisk.

Hope this helps!

[LEM]

Hi, Erik!In my case, there are no firewalls/ACL.
I think that second response should be from end device. But there are three hops.

[Erik_Auerswald]

Hi,

traceroute prints asterisks (*) when it does not receive a TTL Exceeded message for a packet. A common reason for not receiving those are firewalls in layer 3 (routed) mode configured to not create ICMP messages.

Erik