Issue with MPLS Lable for TE

Chetan Kumar Ress · ‎08-06-2010

Dear Friends,

Every thing was working fine , The issue occur when I was testing the TE link.

Two TE was configured with mpls ip command.

In output of sh mpls forwarding-table, I found that it’s showing me POP TAG. (Was expected the same )

When I shutdown the both TE ( Tunnel interface ) on PE1 and unshut then I saw that next-hop was tunnel as same earlier & was in routing table also every this was correct but my VRF traffic was not passing through TE or through any other way . Because in routing table it was showing the next hop was accessible via tunnel. So it won’t take any other path. Entire communication was stuck.

All traffic was getting dropped. After investigating I found that in PE1 the output for sh mpls forwarding-table

The both tunnel was showing as Untagged [T] on PE1 & in PE2 it was showing POP TAG.

I cleared the mpls FIB counter but still issue persist. I reload that router and every this was working fine.

After reload it was showing me POP TAG on both routers.

Can any one explain what is the issue?

Regards

Chetan Kumar

Giuseppe Larosa · ‎08-06-2010

Hello Chetan,

please attach your configuration

>> Two TE was configured with mpls ip command.

this is not the way we generally use MPLS TE tunnels they are used as an alternative to automatic LSPs built by LDP

running LDP over MPLS TE tunnels is a different matter, it can be done for scalability in inner core but between only two routers it may be just a good exercise.

Hope to help

Giuseppe

Chetan Kumar Ress · ‎08-06-2010

Hi Giuslar

Will share the complet config afetr two days. Currently i don't have .

The tunnel config was look like this :

interface Tunnel100

ip unnumbered Loopback0

mpls ip

tunnel destination x.x.x.x

tunnel mode mpls traffic-eng

tunnel mpls traffic-eng path-option 1 explicit name Chetan

no routing dynamic

I was trying to config MPLS TE per VRF with two tunnel & " mpls ip " command to use label switching & as the MP-BGP was not next hop for this VRF.

so every thing was working fine but when i shut one tunnel then traffic was goining through other tunnel & after doing vice versa i saw that traffic is get dropped. So after that i find that there was issue with MPLS LABEL. On headed PE it was showing me as Untagged & in tailed router is was showing POP TAG.

Please let me know the command is used to refresh that mpls lables ( i use clear mpls coun ). But in above senario i reset the neighbor , then also the same issue. After rebooting the router it was working fine.

Regards

Chetan Kumar