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New Member

DSP resource for MTP

Hi All,

we have 3845 ISR router with 4 full PRI. I need to configure MTP in the router to support incoming fax support to communicate with Microsoft Exchage to receive fax. there are one PVDM2-48 and one PVDM2-96 installed on the router. so (112-96=16) 16 dsps are only available for MTP which is not enough. these are my questions:

1- if I setup:

#dspfarm profile 1 mtp

#max session hardware 112

is this command allocate all DSP for MTP and nothing would be available for PRI?

2- if I setup:

#dspfarm profile 1 mtp

#max session software 500

is it going to utilze high CPU?

3- Can I use mix software and hardware DSP for MTP?

very appreciate for any suggestion.


Cisco Employee

Re: DSP resource for MTP

You should start by learning how to size the DSPs because your calculations are totally wrong

1st, there are no PVDM2-96 unless you have created them

High-Density Packet Voice Digital Signal Processor Module for Cisco IP Com Sol

2nd, a DSP are 16 channels, so the biggest PVDMs has only 4

3rd, for 16 DSPs you need 4 X PDVM2-64

Exactly how you managed to get the 112-96=16 DSPs????? i can't figure where you got the numbers

I would recommend you to go to the router, do a sh tech and find out exactly what you have before doing any math

Once you know what you got, refer to this link to see how many sessions you can get:

Cisco Enhanced Conferencing and Transcoding for Voice Gateway Routers

If you have any kind of voice termination (PRI, FXO, FXS, etc)on the router then see how many DSPs are still free, if they're configured they already have DSP channels allocated which you cannot use.

You can use both SW and HW MTP

Configuring Enhanced Conferencing and Transcoding for Voice Gateway Routers

You can also use the DSP calculator to learn all this



if this helps, please rate



if this helps, please rate