trace from a linux through MPLS cloud

[8dstaicu]

Hi,

I got this trace from a customer.

1 10.50.128.254 1.940 ms 16.754 ms 16.482 ms

2 10.50.128.253 0.837 ms 0.733 ms 0.881 ms

3 192.168.105.181 4.040 ms 4.250 ms 3.982 ms

4 192.168.16.89 44.597 ms 44.532 ms 44.772 ms

MPLS Label=27 CoS=5 TTL=1 S=0

MPLS Label=129 CoS=3 TTL=1 S=0

5 192.168.18.141 15.380 ms 37.758 ms 10.681 ms

MPLS Label=129 CoS=5 TTL=1 S=0

6 192.168.18.142 23.174 ms * 22.015 ms

Can someone give me an explanation about the way linux box is able to find MPLS tags from the network?

[rais.ahmad]

Such traceroute implementations have been around and use PING/TRACEROUTE extensions for MPLS. This is one of the simple ways we can troubleshoot MPLS problems.

For more information review this draft from ietf: 'draft-ietf-mpls-icmp'

Thanks.

[Harold Ritter · Accepted solution]

The routers will include that information in the ICMP TTL expired messages according to the following draft:

"ICMP Extensions for MultiProtocol Label Switching"

http://www.ietf.org/proceedings/01mar/I-D/mpls-icmp-02.txt

It appears that Linux implements this draft too.

Hope this helps,