Inter-AS MP-BGP Multicast

Unanswered Question
Oct 9th, 2009
User Badges:
  • Gold, 750 points or more

Running inter-as MP-BGP multicast between PE's using MDT under the VRF without a problem. Problem is GRE dynamic tunnel is built using my loopback interface in the global routing table and not in the VRF. All PIM/MSDP is done on loopback interface within the VRF between PE's so when i block AUTO-RP messages ( between PE's, AUTO-RP messages is still exchange on loopback interface in the global since MDT is using that to build the GRE dynamic tunnel. Is it possible to be selective on which interface MDT uses to build dynamic GRE tunnel between PE's?

Is manual GRE tunnel the way forward?

Please let me know if you need clarification


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4 (1 ratings)
francisco_1 Fri, 10/09/2009 - 08:24
User Badges:
  • Gold, 750 points or more

after researching this i now undertsand that the loopback in the global is used because that's what BGP uses to established adjacency between PE's. so MDT uses that.

Laurent Aubert Wed, 10/14/2009 - 18:45
User Badges:
  • Cisco Employee,

Hi Francisco,

MDT group is used to encapsulate customer multicast traffic so it's part of the SP domain or the global routing.

In case of Inter-AS Option-B, you need to use the RPF-vector PIM extension so you don't have to redistribute the PE loopbacks between both AS.



danailpetrov Thu, 10/22/2009 - 05:39
User Badges:

As far as I can remember you can do this by choosing a bgp next-hop option located in VRF configuration.

for instance:

ip vrf a

bgp next-hop Loopback10

Hope it helps!

Kind regards,


Laurent Aubert Mon, 03/01/2010 - 20:02
User Badges:
  • Cisco Employee,


We support MTR on 7600. With MTR, you have a dedicated table for RPF check and you decide which routes from the unicast tables you want to import on the RPF table. But you have only one RPF table even if you have several unicast RIB (or topologies)

Other than that, you will have to use static mroute.




This Discussion