Multicast MOH on gateways

[mbakman]

Has anyone successfully configured Multicast MOH to work with your gateways. I have a 2600 MGCP PRI and a DT-24+. Not sure if the DT-24+ supports it but I know the 2600 supports multicast MOH but I can't find any documentation on it. The only thing I can get my hands on is the ccm-manager music-on-hold command in the router.

I have multicast MOH working for the 7960 IP Phones and it appears the 2600 gateway attempts to join the multicast MOH group. I see the IGMP join message go out but the router never forwards it. The perfmon counter for MulticastMOHresourceActive in Callmanager increments but still no packets arriving at the 2600. I'm guessing this is a routing issue but the fact that its working for my phones is confusing. The phones and the 2600 gateway is in the same vlan. The callmanager is in a different one. This indicates to me that multicast routing is working properly between the callmanager and the phones.

Any idea where I should look next?

[gillins]

what code do have running? I am running c3640-is-mz.122-11.T.bin on a gateway that is multiple hopes away and all is good. with this code the gateway should get it correct config to work from the callmanager if you are running mgcp.

Scott

[mbakman]

I'm running CCM 3.1(4a) and 12.2(11)T on the 2600 gateway. I don't need to be running any multicast routing protocols on the gateway right..?

[vassatrian]

It is all depends.

First of all your routers need to “listen” MOH multicast group. And secondly, in order to forward multicast packets across the network routers need to run some sort of multicast routing protocol like CISCO PIM-SM or PIM –DM.

Also Router never forwards IGMP messages: they have TTL=1. If router runs multicast routing protocol, IGMP message arrival will trigger router to “join” multicast routing tree by sending “join” multicast routing protocol messages up to the “source” or “rendezvous point” – it all depends on what sort of multicast routing protocol do you run.

Correct me if I am wrong, CCM MOH via multicast – it is delivery MOH via industry based multicast routing technology - you still need to configure multicast routing for your network: depending on topology of course.

I believe that gateway will not do multicast routing just because they “talk” MGCP with CCM.

Regards,

Vakhtang

[mbakman]

After further investigation we narrowed the problem to IGMP messages not coming out of the 2600 router. Debug ip packet and ccm-manager music-on-hold shows that the Multicast MOH group is being requested but we can not see it on the wire. Something is not right with our router/gateway since CDP is not working on it either.