Automatic multicast source switching

[rkatel]

Hello,

I have three routers A, B and C. Routers A is connected to a multicast source S1 and router B to a multicast source S2. The two sources S1 and S2 broadcast the same multicast streams. The RP addresses are also identical on A and B.

A multicast client is connected behind Router C. On Router C, I have configured a static route to the RP on A through a tunnel, and likewise to B. Both routes have the same administrative distance. For multicast routing, I configured the PIM. By default, streams are always received from B, because the address of the tunnel to B is higher than that of the tunnel to A.

If B is stopped (or the route becomes unavailable), data is received from A. But if B is still reachable and S2 is no longer sending anything, no data is received, even though A same and S1 are working very good.

I would therefore like to configure the routers so that if B is reachable, but the data is no longer available, that the reception of the data automatically switches to A. I tried the Load Splitting with ECMP ("ip multicast multipath"), but without success.

Can anyone help me ? Thank you in advance.

[Giuseppe Larosa]

Hello @rkatel ,

Can you explain why you are using tunnels between RC and RB and between RC and RA?

There is a non multicast capable network in the middle ?

>> The RP addresses are also identical on A and B.

>> A multicast client is connected behind Router C. On Router C, I have configured a static route to the RP on A through a tunnel, and likewise to B. Both routes have the same administrative distance. For multicast routing, I configured the PIM. By default, streams are always received from B, because the address of the tunnel to B is higher than that of the tunnel to A.

>> But if B is still reachable and S2 is no longer sending anything, no data is received, even though A same and S1 are working very good.

Because you are using the same RP address on RA and RB your scenario is that of  Anycast RP .

I think you need to configure the MSDP protocol between RA and RB using two unique loopback addresses in this way each RP can inform the other about live multicast sources in its own sub domain.

About MSDP for PIM v4 you can look at the following link:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/6-x/multicast/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_Multicast_Routing_Configuration_Guide/b_Cisco_Nexus_9000_Series_NX-OS_Multicast_Routing_Configuration_Guide_chapt...

I couldn't find an exact example of MSDP used for PIMv4 Anycast RP.

You will need also top provide a multicast enabled path between RA and RB in case of need if S2 stops working RB can get the acrive stream from RA.

Hope to help

Giuseppe

[rkatel]

Hello @Giuseppe Larosa 

And thank you very much for your answer. 

You're right, I configured tunnels between RA and RC and between RB and RC because there are non multicast capable and non multicast enabled equipments in the network. Actually, RA and RB are in the same network (same room), while RC is in another country.

So, I will try what you suggested and get back to you.