Multicast MOH IP address

[jjia]

Hi,

Two nodes of CallManager clusters,CCM 3.3(3). Tried to configure Multicast MOH for remote sites.

I am just wondering if I can use the same multicast ip address on the both callmanager servers, for example 239.1.1.1?

Thanks,

JJ

[thisisshanky]

JJ,

A quick read about MOH on the SRND doesnt say much about what you should do when you have redundant MOH servers, (regarding multicast address) - Unless I missed something. I would believe you can set it to the same, as the backup MOH server will not be used, unless the first goes down (or is busy/not available).

[rcfoltz]

No, the basics of multicast transmissions would prevent this. When you enable multicast on a MOH server, it begins streaming the file to the Multicast address (239.1.1.1 or whatever) immediately. When you enable the second, it too will begin streaimg. When a call gets placed on hold the device is told to accept the stream going to the 239.1.1.1 address, and it would recieve 2 copies of the stream. What you will hear is messed up audio as the phone plays them packets in the order received. You have 2 options.

First, Use MOH on the primary MRGL and unicast on the secondary.

Second, you can stream MOH from the remote sites gateways using multicast to the same address. If you disable Multicast across the WAN then the phone will play the multicast stream from the local router. This will also save you bandwidth.

[allan.thomas]

Have you attempted to enable Multicast MoH on both CallManagers ?

I would be surprised if under CallManager 3.3(3) it allows you to enable Multicast MoH with first changing the Multicast IP address.

I certainly know that this is the case on CCM 4.1.2. You have to change the range or starting address of the Multicast IP address.

Allan.