Multicast ASM & SSM

[Ab26]

Hi !

I have a multicast setup in my network using PIM-ASM.

For some reason a router in my network stopped responding to IGMP requests. Although the show commands for IGMP showed everything works. Has anyone experienced the same thing? I’m planning to upgrade and restart the router and see if this resolves the problem. 
Another question, one of my customers is complaining that the multicast traffic stops every 30 seconds and starts again. I have checked the multicast table (sh ip mroute) and I can see the streams have been there for several weeks. I can see the packet count is increasing (mfib). I have checked the unicast routing table, and the routes has been there for a long time (no route flapping). I have checked errors and physical interfaces and none is there. Does anyone have an advice? What kind of troubleshooting I could do to verify that there is no problem on the network side?

I want to ask about converting to SSM, would it be more beneficial if the customer has only few sites? So is there more benefit of using SSM over ASM other than the ease of configuration?

[paul driver]

Hello
You don’t say what ASM model you are using; So the assumption will be pim-sparse mode and if it is what source discovery feature are your using for RP (Static. Dynamic – Autorp-BSR)

With SSM then you don’t require any source discovery as in source specific multicast you use IGMPv3 and specify a unicast source and an multicast group you wish to join, as such no requirement for any RP and any (*.G) entries in the mroute table due to the fact SSM allows source/receivers to be able to join together directly over the shortest path of the network instead of a shared distribution path as in you would in ASM

[sidshas03]

This issue may be related to IGMP querier election or IGMP snooping behavior on Layer 2 devices. Please check if another device has taken over as the IGMP querier, and whether it is functioning correctly. Also verify if IGMP snooping is enabled on the connected switches, and whether it’s aging out group entries prematurely. It’s also worth checking IGMP version compatibility between devices.

As for switching from ASM to SSM, it can simplify the setup especially in smaller networks by removing the need for an RP and avoiding shared trees. If your applications and receivers support IGMPv3 and you know the source IPs, SSM can provide more predictable and efficient multicast delivery.