[cisco-voip] Multicast MOH (MMOH) SRND Question

[Anthony Holloway]

Thank you for taking the time to respond Tim.

You have provided me with a clearer insight into the passage, and I am now
in agreement with your explanation.

On Wed, Sep 18, 2019 at 10:29 AM Tim Smith <tim.smith at enject.com.au> wrote:

> This looks to be specific to re-broadcasting (which I haven’t had the
> pleasure of playing with yet)
>
>
>
> Looking at the diagram in there. I assume you configure a new source with
> a multicast address on your MOH server.
>
> If it’s set to re-broadcast, it’ll be looking to capture the input stream
> from that address.
>
>
>
> Is it just saying since your MOH server is receiving MMOH on say
> 239.1.1.1:16384
>
> (And would then re-broadcast this as Unicast where required)
>
> It won’t send any multicast on that same address
>
>
>
> But you can configure a multicast address – on that source – which means
> it re-broadcasts the original stream as multicast on a new multicast
> address as well.
>
>
>
> MoH server for re-broadcasting + External Multicast source must be on same
> LAN (or at least have multicast routing connectivity between them) for the
> rebroadcasting – so if your server is receiving on one address, you
> wouldn’t want to be sending out on the same address.
>
>
>
> That’s the way I read it which I think makes sense to me.
>
>
>
> Cheers,
>
>
>
> Tim
>
>
>
> *From:* cisco-voip <cisco-voip-bounces at puck.nether.net> *On Behalf Of *Anthony
> Holloway
> *Sent:* Thursday, 19 September 2019 1:00 AM
> *To:* Cisco VoIP Group <cisco-voip at puck.nether.net>
> *Subject:* [cisco-voip] Multicast MOH (MMOH) SRND Question
>
>
>
> I was helping someone troubleshoot a MMOH issue and what was happening was
> that CUCM audio source, MOH Server, and MRG were all setup to do MMOH.
> There was also a hardware MOH device on the network, which was sending MMOH
> on the same IP address (239.1.1.1) as the CUCM MOH Server.
>
>
>
> When I pointed out that this would be a problem, I was shown the following
> statement from the SRND:
>
>
>
> *"If the multicast MoH server and the audio source are configured with the
> same multicast group address, when Phone B is placed on hold, it will
> receive the multicast RTP audio stream (E) from the original multicast
> stream (B) broadcast by the SRST router. In this case the MoH server does
> not send the audio because it is aware that the destination multicast IP
> address group is the same as the external audio source multicast stream (B)
> broadcast by the SRST router."*
>
>
>
> Source:
> https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11/media.html#pgfId-1393039
>
>
>
> Now, a TAC case was opened, and TAC said it should have done what the SRND
> is stating, but I am doubtful.  I think the wording in the SRND is poor,
> and that perhaps it only pertains to the Fixed source of 51, and not just
> any source you create.
>
>
>
> So, I'm asking for your understanding and knowledge of how this works, to
> clarify this aspect of MMOH for me.  Please read the entire section of the
> SRND linked, because context is important here.  I only provided a snippet.
>
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