interVRF multicast

[andy!doesnt!like!uucp]

Hi Gurus

i'm looking for the solution to enable multicast any-source in multiVRF hierarchical campus deployment. Deployment has multiple distribution switches where both recievers & senders live (simplified diagram attached). After some learning i can see only option  of multiple  (2xtunnelsxN_of_distributionsxN_of_coresxN_of_nondefault_VRFs) GRE PIM-enabled tunnels between Distribution switches & Core with core-ends in default VRF. As unicast default route is on the FW, static mroutes will fix RPFs for the sources in each VRF. Highly unscalable... + unresolved topic: how to enable MC between wireless Guest users terminated on the Core & default VRF?

Any ideas?

[Giuseppe Larosa]

Hello Andyo,

looking at this old thread

https://community.cisco.com/t5/mpls/intervrf-multicast/m-p/1120315

They suggest a feature called Multicast VPN Extranet Support.

The link is still reachable

https://www.cisco.com/c/en/us/td/docs/ios/12_2sb/feature/guide/extvpnsb.html

Restrictions for Configuring Multicast VPN Extranet Support

•The Multicast VPN Extranet Support feature only supports Protocol Independent Multicast (PIM) sparse mode (PIM-SM) and Source Specific Multicast (SSM) traffic; PIM dense mode (PIM-DM) and bidirectional PIM (bidir-PIM) traffic are not supported.

•When configuring extranet MVPNs in a PIM-SM environment, the source and the rendezvous point (RP) must reside in the same site of the MVPN behind the same provider edge (PE) router.

You must configure either the receiver MVRF on the source PE router (Option 1) or the source MVRF on the receiver PE router (Option 2) for extranet links to be created. Once configured, RPF relies on unicast routing information to determine the interface through which the source is reachable. This interface is used as the RPF interface. No additional configuration is required for RPF resolution. The Multicast VPN Extranet Support feature supports RPF from one VRF to another VRF, from a VRF to the global routing table, and from the global routing table to a VRF.

I think this feature if is supported on your devices is quite better then trying to setup p2p GRE tunnels with PIM over it.

It uses the extranet concept (playing with route targets in MP BGP) and the use of the same MDT group ( Global routing table mcast address for transport inside GRE of Customer VPN mcast packets = draft Rosen MVPN)

If you have ASR 1000 in your network you can use NG MVPN that should be even better.

Hope to help

Giuseppe

[andy!doesnt!like!uucp]

Hi Giuseppe

i've already learnt this article. In my case network doesnt implement MPLS. Even if it were i would endup with full mesh of MBPG sessions between distribution switches which unlikely would cut the configuration & maintenance burden. I'll start with attempt to build mesh of GRE-tunnels between core-switches (totally 12 tunnels originated/terminated from/on each core N7K).

anyway thank u for advice

[Giuseppe Larosa]

Hello Andyo,

for MP BGP you can use route reflectors to avoid the full mesh problem.

And multicast forwarding in this solution uses GRE Tunnels not MPLS so it should be able to work also in a VRF lite context.

Anyway, you know your network environment and you make the more appropriate choice.

Best Regards

Giuseppe

[andy!doesnt!like!uucp · Accepted solution]

hi Giuseppe
just wanted to let u know the design with 4 gre-tunnels from target vrf toward 2 other made the trick. all on n7k . anycast to in target vrf.
thanks to all