Re: Problem with Multicast and VRF Lite

On Tue, Mar 8, 2011 at 9:49 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
>> Thanks for all that info! This started out as just me playing with VRF
>> Lite because we may want to use it at work for a particular
>> application. There is another lab area where I might want to use this
>> other idea I'm trying to get to work. Basically, we want to have a set
>> of lab routers and switches that are subdivided into multiple virtual
>> labs that are almost entirely separate from one another. In this lab,
>> we have a large number of multicast video sources. I'd like to be able
>> to pull those sources onto a router into a single VRF. Then create
>> VRFs for those other virtual lab instances, then somehow allow these
>> other VRFs to join the multicast streams that are present in the
>> "source" VRF.
>
> What you might try doing is adding another router between your multicast sources and the VRF-lite router, and connect them via GigE that is trunking a different VLAN for each VRF. On the new "staging" router these VLAN subinterfaces would be on the global routing table all running regular global PIM. On the VRF router each subinterface would be in a separate VRF, and run separate VRF aware PIM processes. Technically you wouldn't even need to run unicast routing between them, because on the VRF router you could put VRF aware static multicast routes to do your RPF lookups.
>
> You could try the hardware loopback between the different VRFs but it might not work. I've seen some platforms that drop self-originated frames if they come back in a different link. There must be some ASIC level logic that says "My MAC address is A, don't accept packets in if they're sourced from A". As usual YMMV though.
>
> Good luck!

That's an interesting idea. We have plenty of 4948s lying around. We
could probably figure out a way to use one or two of those to
terminate our multicast source connections and then trunk them to the
ASR9K in our lab.

The downside to that approach is that for each VRF that joins a
multicast stream across that trunk, the bandwidth used on the trunk
increases. I was hoping to find a way to bring the sources into a
router and then basically use the features within the router to
replicate that traffic out to the other VRFs. If it could all be done
in hardware, our only limitation would be ability of the router to
replicate the multicasts. In the case of the ASR9K, there is a ton of
capacity there.

This is all great food for thought. Thanks!

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Received on Tue Mar 08 2011 - 22:01:40 ART