Thursday, March 26, 2009

MTI(Multicast Tunnel Interface) is Coming Up But Not Pim Neighborship

Yesterday I got a query on MVPN:-
In MVPN MTI(Multicast Tunnel Interface) is coming up but but end to end pim neighborship on MTI tunnel is not coming up. What is reason for this and how this can be possible?

The question is very intectually. Actually the formation of MTI depends on the default MDT group which is being mentioned under vrf. So once the reachability of that group available in the MPLSVPN cloud MTI tunnel comes up. But PIM neighborship depends on the pim sparse-dense-mode or sparse-mode and if it is not coming up definately in the path pim sparse-dense mode or sparse mode is missing.

shivlu jain

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Danail said...

Hi there!

I'm just passing through, but I can drop my 2 cents for that. The problem really may be in the CORE's multicast, but sometimes the MTI actually is choosing a wrong interface for source address. I tried a few thing to workaround it - nothing helped. Nothing but one - it's a command applied on customer's VRF.

ip vrf ABC
bgp next-hop loopback 0

This command will force the MTI to be created using proper Loopback interface.

Danail Petrov

Shivlu Jain said...


Thanks for your observation.

aldebaran said...

Hi...I put on command bgp next-hop loopback 0 but neighbor MTI down yet..whats happens?

output command show ip pim mdt bgp

R4#sh ip pim mdt bgp
MDT (Route Distinguisher + IPv4) Router ID Next Hop

It's very strange