music on hold not working in multicast mode

Posted on 2011-09-04
Medium Priority
Last Modified: 2012-05-12
Hi there,

I'm getting tone-on-hold instead of music-on-hold with multicast enabled between 2 Cisco IP phones on same LAN. CUCM version is 7.1.3. CUCM MOH Server is configured with multicast I.P and has max-hops set to 30. MRG uses this MOH server and has 'Enable multicast MOH' ticked. This MRG is in use by MRGL and eventually by the device pool that the phone is assigned to. Music-on-hold audio source is 1 and it is a .wav file. When uploading it, CUCM converts it into its right ulaw and alaw format. I restarted IPVMA service after uploading this too.

On LAN is a a Cisco Router (2821) where multicast routing and PIM Sparse-mode is enabled. Commands I've used are below

// To enable Multicast routing
Router(config)# ip multicast-routing

// Enabling PIM on the LAN interface
Router(config-if)#ip pim sparse-mode

//Specifying RP Address on router
ip pim rp-address

Switch by default has IGMP snooping enabled so don't need to configure anything there, do i ?

In CUCM Fall-back mode, I've got the following
moh port 16384 (and this is the same multicast I.P as configured in MOH server).
Note the gateway itself does not have any MGCP, CCM running as all I'm doing is trying to source MOH using multicast. I restared IPVMS and CUCM Service but still no good and I contiue get tone on hold instead.

Wireshark shows what looks like a broadcast storm with lot of packets from CUCM MOH server to the multicast I.P when tone-on-hold plays. 'show ip mroute' also shows multicast path established but all i get is TOH. SDI traces show no media resources available which shouldn't be the case as phone is using the right MRGL --> MRG --> MOH Server --> MOH source.

Any help would be greately appreciated. If you need snapshots of config or router config, please let me know.

Question by:nabeel92
  • 2
LVL 20

Assisted Solution

by:José Méndez
José Méndez earned 2000 total points
ID: 36483822
Tone on hold may be the result of multicast misconfiguration. Please make sure the MOH Server, Audio Source and MRG all have the multicast enable flag.

Since multicast MOH is always streaming out non-stop, you will always see packets broadcasting and flooding the network. Also make sure the phone placed on hold is the one assigned with resources.

Are you saying you have a CallManager and a router streaming MOH within same LAN?

Author Comment

ID: 36486191
Yes - CUCM and 2 phones are in the same LAN.

Interesting enough, I specified audio source file on Phone's 'User Hold MOH audio source' page but still was unable to get music-on-hold. Shouldn't this setting override what's configured in MRGL as the phone in the same LAN is sourcing MOH to next phone? Since MOH doesn't get played in this scenario, I'm assuming it may not be multicast but something else.

On CUCM CLI, I do get a warning 'IPVMS - excessive mixer calls'. I googled it but it talks about this warning relevant to jitter and not really MOH ?

MOH Server, audio source and MRG all have multicast ticked. Both phones are in the same pool using same MRGL.
LVL 20

Accepted Solution

José Méndez earned 2000 total points
ID: 36486404
The audio source you configure on Phone A on the User Hold field determines which songs is played. The MRGL of Phone B dictates from which MOH server the song will be received.

The "excessive mixer calls" is a bug and might be affecting your system (look it up with Cisco´s bug toolkit), you already pointed out that the traces complain about "no media resources available".

This could be a configuration issue or  the bug that I made reference to. Can you upload a packet capture from the Callmanager MOH server configured as Multicast MOH?:

utils network capture eth0 file MOH count 10000000000 size all

Then download with RTMT.

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