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UCM MoH Multicast Address Ordering for Audio Sources

Today was the first time it mattered to me what multicast group address each MoH Audio Source is sending to. The MoH server specifies a starting address (e.g. 239.1.1.1) and to increment by IP Address. It appears that the base address is choosen for the highest numbered multicast-enabled audio source. For example, if UCM has two sources enabled for multicast, source one (1) will choose 239.1.1.5 while source two (2) will choose 239.1.1.1. The increment-by-five piece I understand (four available MoH codecs). This is just the address selection order that seems odd. For reference, this is 8.0.3.10000-8.

Is anyone else able to confirm this behavior? It seems backward to me but I wanted to illicit others' input before assuming it is a bug and opening a TAC case.

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Accepted Solutions
kvancoil
Cisco Employee

Hi Jonathan,

Do you remember in which order you enabled your audio sources for multicast? The associated multicast IP address is not directly related to the audio source ID.  There is a database rule that takes the information from MOH audio source table (those that are multicast) and each multicast MOH server and updates the MOHServerMulticastInfo table with records for each audio source ID/codec/MOH Server device.  This database processing will assign multicast IP addresses in the order that the MOH audio sources are enabled for multicast.

So in your instance:  if audio source #2 was enabled for multicast befroe #1 then it received the 1st 4 multicast IP addresses and #2 received the next 4 (as the DB select shows).

Now if you disable multicast for both #1 and #2 and then reenable multicast for #1 first and enable multicast for #2 then I believe you will have the multicast IP addresses you are expecting. However  this may change if other multicast settings (MOH Server or second MOH server added) are changed.

You can check the ip address / audio source id relation easy using the below query:

run sql select * from mohservermulticastinfo

Cheers,

Kristof

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1 REPLY 1
kvancoil
Cisco Employee

Hi Jonathan,

Do you remember in which order you enabled your audio sources for multicast? The associated multicast IP address is not directly related to the audio source ID.  There is a database rule that takes the information from MOH audio source table (those that are multicast) and each multicast MOH server and updates the MOHServerMulticastInfo table with records for each audio source ID/codec/MOH Server device.  This database processing will assign multicast IP addresses in the order that the MOH audio sources are enabled for multicast.

So in your instance:  if audio source #2 was enabled for multicast befroe #1 then it received the 1st 4 multicast IP addresses and #2 received the next 4 (as the DB select shows).

Now if you disable multicast for both #1 and #2 and then reenable multicast for #1 first and enable multicast for #2 then I believe you will have the multicast IP addresses you are expecting. However  this may change if other multicast settings (MOH Server or second MOH server added) are changed.

You can check the ip address / audio source id relation easy using the below query:

run sql select * from mohservermulticastinfo

Cheers,

Kristof

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