How to tell when DSP channel is in use

gene · ‎07-02-2007

According to the documentation I have read when using PVDM's for voice termination and a call comes in at 711 it should use one DSP channel if the call comes in at 729 it should use two. When I do the commands on the router such as show voice dsp detail it only looks like one DSP channel is in use even when the call is 729. How can I tell what is going on with the DSP's? Also I know when you build a PRI it dedicates 1 channel per port for the 23 ports how does it allocate for if the calls are 729?

paolo bevilacqua · ‎07-02-2007

Hello,

it's a bit more complicated than that. Depending on the router you are using, one DSP can handle a certain number of g729 calls. In the past this number was fixed or configured depending on "codec complexity". Now this concept has gone away and the DSPs are give additional calls depending on the actual load they have ("flex allocation"). There is a DSP calculator on CCO that will tell you all the numbers, it requires customer-level access.

The basic command to see what the DSPs are doing is "show voice dsp".

Hope this helps, please rate post if it does!

gene · ‎07-02-2007

I am using a 3845 with a PVDM2-64

The document I am looking at says that a medium complexity codec (729) it can do 32 voice termination and low complexity (711) it can do 64. When I do a show voice dsp detail I can see all the DSP channels (I think that is what I am looking at) but it seems to only show one channel tied up weather a call is 729 or 711. This makes no sense to me. How can you tell which DSP's are in use and how many you still have free.

paolo bevilacqua · ‎07-02-2007

Yes, with g.729a (note, a suffix and not b) the DSP tools reports you can terminate 32 calls with a pvdm2-64.

Now when you look at the command output, channel actually means B-channel on the POTS interface, and rightly one channels is used per call independently from the codec used.

The PVDM2-64 has 4 DSPs, each good for 8 calls, 4 x 8 = 32.

Hope this helps, please rate post if it does!