Multicast sparse mode - RP with one router and multiple switches

[oj]

I have two routers/firewalls in active-passive mode which have two nexus switches connected. The two nexuses in VPC then have one link each to edge switch. The nexuses have servers connected and they serve video streaming to clients connected to edge switches. Gateways are on the router/firewall (don't ask me why please).

I would like to configure multicast in sparse mode just wondering what is the best practice if there is only one router.

Will the active router/firewall be the RP (loopback0) IP)?

Which device will be the querier?

Do I just set pim on each router interface and snooping on nexuses and edge switches?

Can the nexus be the querier or take over some processing off the router/firewall?

Thanks

[paul driver]

Hello
If you need to MC to traverse multiple routed vlans then you need to enable PIM on the router that is providing the L3 routing, in your case it would be router.

So you are correct you would enable PIM on the routers routed interfaces, As for the nexus you could make them the igmp querier so to proxy MC for the receivers and igmp snooping for all the vlans

[oj]

Thanks Paul.

Think of it as one router or router on a stick.

Is there a specific config to have the nexuses act as queriers? 

If there are other L2 switches connected to the nexuses do they also get all MC details down from the nexuses?

Regards

[Giuseppe Larosa · Accepted solution]

Hello oj,

the router will act as IGMP querier as well because when you enable PIM on a routed interface you are also enabling IGMP .

So all the L3 multicast configuration will be on the router with Nexus devices and other switches just using IGMP snooping to populate the L2 OI list for each VLAN and multicast group.

Also  IGMP querier is intended only for those VLANs where no full multicast router is connected to and this feature is not able to interact with a PIM/IGMP router for example it is not able to take part in the IGMP querier election as regular mcast routers do.

Hope to help

Giuseppe