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CFB/Transcoding with DSPs & CallManager

I have an NM-HDV with two banks filled to support conference bridging and transcoding. I'm trying to figure out exactly how many sessions of each to allow.

1) If each 3 DSP bank supports 12 sessions, this then means that the two DSPs together support 24 sessions total (CFB/trans combined)

2) Is it better to use the NM-HDV just for transcoding and allow CallManager to be the CFB? We have 40 G729 sites going to one CM cluster at the network HUB. I would think this would be a better utilization of DSP resources..

3) With a conference, is a session considered a participant, or the whole conference itself?

Cisco Employee

Re: CFB/Transcoding with DSPs & CallManager

You will alway want to use HW resouces before using SW resources for transcoding. Here is a page that explains it a bit:

Re: CFB/Transcoding with DSPs & CallManager

You should always look to transport the voice the least distance.

If the handsets in a conference are on the same physical site as the NM-HDV, then they should be configured in a device pool which has the appropriate Media Resources to use the Conference bridge / transcoder local to them.

There seems little point in having 3 users at a site backhauled to a central site to do a conference.

If all of the conference participants are from different sites, then I would again keep them on the same hardware, there seems little point in passing all their traffic to one box, then offload it to a second box, when the first box could do both jobs. Don't forget you also add in additional latency and subject all the streams to possible further QoS issues on the network.

Keep to as few hops as possible would be my suggestion based on experience.