Multicast GRE Tunnel

[mduhra]

Hi

I'm trying setup a Multicast GRE Tunnel between two sites, similar to this Cisco doc:

http://www.cisco.com/en/US/tech/tk828/technologies_configuration_example09186a00801a5aa2.shtml

Have a few questions:

1. We've been assigned a Multicast IP from our IP management team, 239.x.x.x. Do we define this IP on one of the site routers?

2. Or do we define this 239.x.x.x IP on a RP? Which will announce this group out.

3. If there are no other RP's in this domain, then I need to define one of these routers as an RP?

Thanks in advance!

-MD

[Nagendra Kumar Nainar]

Hi,

Mcast IP address is not required to be assigned to any router/interface.Multicast over GRE tunnel is required in situation where 2 sites requiring multicast traffic to be exchanged and are separated by network whcih doenst support multicast flow.

Can you explain the purpose of this Mutlicast group being assigned to you?. Based on which we can suggest the design requirement.

Regards,

Nagendra

[mduhra]

Hi,

Thanks for the reply.

We have two sites. With regards to this traffic, SiteA will have a few CCTV (video cameras) and an NVR (network video recorder) and a few PCs, SiteB will have two desktop PCs. What the customer is looking for is real-time streaming video from the cameras to be available for viewing at both sites simultaneously on all PCs. Our thoughts were to setup a multicast group between these two sites over a GRE Tunnel. Multicast is being run in other parts of this customers network, however, it's used for much larger applications (software deployments, large video presentations, etc...).

We're trying to keep this as simple as possible, hence the GRE Tunnel. In the cisco example, they define Multicast Src Group and Rec'vr Group, so that's where I get the 239.x.x.x IP from. My question is, where does this get defined? on a RP or do I need to select either SiteA or SiteB to be a RP for this video traffic.

Now, if we must use the existing RP in the global network for this client, then we'll put that request in. But I feel that this site to site multicast GRE tunnel may be a simpler solution as ONLY these two sites will require this multicast stream.

Regards,

-MD

[Mohamed Sobair]

Hi,

You simply have Site A as your RP for the group 239.x.x.x.

The easiest solution is to have Static RP mapping on both Site A and Site B , If you have a multicast over GRE tunnel, then make sure a bout two things:

1- enable pim Sparse-mode on the GRE tunnel.

2- Make sure your RPF doesnt fail at Site B, by creating static Mroute pointing to the RP address with the GRE as exit point.

Thats all you need...

Let us know if this answers your question,

Regards,

Mohamed