[c-nsp] Multicast VPN Extranet Routing in IOS XR

[John Neiberger]

> Attempted to do something like this on an IOS platform. Could not get it to
> work. Multicast between VRFs on the same PE was not supported.
> TAC case said:
> "MVPN Extranet support means to build a mdt tunnel between PEs for source
> vrf and receiver vrf. MVPN extranet will work in PIM sparse-mode as long as
> you have source located on one PE and receiver located on other PE. This is
> outlined in below document. Option 1 and Option 2 are Cisco supported and
> recommend design.
>
> http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/extvpnsb.html#wp1054493
>
> For single PE scenario, PE cannot build tunnel to itself. From your
> output, it seems single PE scenario works in dense mode, as you can see
> no RP shown in mroute entry. However, this is not a supported feature.
> As dense mode works in flood and prune fashion, so, when vrf v203
> interface receiving traffic, it has no way to flood interface on vrf 204
> as they belongs to different VRF. ( no pim join mechanism like 2 PEs
> scenario, that pim join can come from mdt tunnel).     So, if you
> configure source and receiver in different vrf from fresh, it would not
> work as dense mode cannot flood different vrf interface. However, it may
> work if you configure receiver interface in same vrf first to make
> packet start to flood, now even after you rename the VRF, the receiver
> is not going to prune itself.     But, this is not a support feature."
>
> We tried all kinds of tricks, including connecting VRF across a back-to-back
> jumper. Ended up putting source/receiver in the same VRF.
>
> --
> Tim:>
>

That's funny. I've been trying to do it in IOS and couldn't get it to
work, either, at least on the platforms in my lab. This particular
feature does appear to be supported on 6500/7600 running 12.2(33)
code. It's also supported on IOS XR, so I'm trying to get it to work
on an ASR9K in my lab at work. I haven't even finished my first
attempt at it yet, but I still thought it wouldn't hurt to see if
anyone else here had ever gotten it to work. It seems to be a tricky
thing to do.

John