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New Member

DSP Codec complexity and PRI channels

So I am adding several new PRI’s to a voice gateway over the next month. I use the DSP calculator and do what ever it spits out as far as DSP requirements but I got to thinking about what it said and did an inventory on some of my other gateways and now I am stumped. So the specific scenario I have is a VG that has two PRI’s in it. It has a single PVDM II 48 module. According to the documentation here http://www.cisco.com/en/US/prod/collateral/modules/ps3115/ps6024/prod_qas0900aecd8016c6ad_ps3115_Products_Q_and_A_Item.html

I can support 48 G.711 channels or 24 G.729 channels. Let’s say I have the dial-peer configured to use a voice class codec of both G.711 and G.729 and the regions are set to force G.729. Now I get 24 inbound calls that are all G.729 will the call fail on the 25th call? I always thought the router would not let you provision the PRI if it could not support all of the channels with the codec complexity of the voice card but it looks like you can over subscribe it.

3 REPLIES
Cisco Employee

Re: DSP Codec complexity and PRI channels

If you have a platform with c5510 DSP, you can use codec complexity flex which lets u oversubscribe.

Pl see:

http://www.cisco.com/en/US/tech/tk1077/technologies_tech_note09186a00800b6710.shtml

HTH.

New Member

Re: DSP Codec complexity and PRI channels

So if I had 24 g.729 calls come in the 25th call would fail even though the PRI was up and had the available channel?

Cisco Employee

Re: DSP Codec complexity and PRI channels

Yeah, when that 25th call hits the GW and IOS tries to allocate a DSP channel

it will not find one as all are in use...

You'd see a msg similar to following on console:

Insufficient DSP resource or FLEXDSPRM-5-OUT_OF_RESOURCES: No dsp's found either locally or globally

HTH.

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