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Sip Call - Payload DMA RPAD

Occasional Advisor

Sip Call - Payload DMA RPAD




I was talking with some colleagues when this question was raised and we couldn’t agree about the answer. Let’s see if someone has an explanation or maybe even tested it.


In one scenario that I’m using a Dma as a Sip Registrar and I have external endpoints registering into the DMA via RPAD. I also have a Rmx on my network to bridge multipoint calls.


In a point to point Sip call between two external users registerd on my dma via RPAD how should the payload be routed? I suppose that just the signaling traffic should go to my infrastructure equipment’s while the rest of the payload should be routed directed between them. Is this right?


In a multipoint call we agreed that all the payload should be routed inside my network as the bridge happens inside the rmx.


Hope to get some answers.




Fabio Rigotto
Message 1 of 2
Polycom Employee

Re: Sip Call - Payload DMA RPAD

Fabio - In order for the DMA to support so many calls and registerations, it doesn't handle the media, only the signalling in order to save on the processing. What I have seen in wireshark traces is exactly what you mentioned, the signalling goes through the DMA and media is directly between the endpoints. In this case, the intrnal leg would be RMX and RPAD and the external would be from RPAD to endpoint in terms of media. What I have not personally tested is what is the media path for 2 external endpoits? I will have to test this and let you know. My assumption is the same, media would go directly between the endpoints.


DMA routing mode, direct or routed, does not make a difference in this case. This only affects signalling and is specific to H323 non-RMX calls. If an RMX is involved, since the DMA is virtualizing the meeting rooms, the DMA will always use routed mode. For SIP, it is always in routed mode regardless what the setting is set to. Only H323 between 2 endpoints like HDX/GS will determine how the signaling is funtioning depending on the mode configured for the DMA. In direct mode, the DMA just gives the other endpoint the IP address information, much like a DNS server gives out IP address for DNS record queries. In this mode, signaling and media is between the endpoints collectively. In routed mode, the DMA handles all the signaling and is responsible for settingup the call.



Message 2 of 2