DSP Issue

Unanswered Question
Jul 22nd, 2009


Just added an FXO card to an MGCP gateway to support some legacy lines. But once i had configured and reset the gateway it ripped 12 channels off my E1 controller

controller E1 0/0/0

pri-group timeslots 1-19 service mgcp


controller E1 0/0/1

pri-group timeslots 1-31 service mgcp

Both should be 1-31

I have shut down the FXO card and removed it from the MGCP config on CUCM but I still get the following (See attached show voice dsp

But why did it take DSP in slot 1 I have conferencing set up as well but I am sure I have enough DSP resource.

Any Ideas (though I will keep looking of how I allocate DSPs correctly



I have this problem too.
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Nicholas Matthews Mon, 07/27/2009 - 12:48

If CUCM is automatically configuring 19 channels instead of 31, this is not going to be a DSP issue.

I've never heard of such a thing, and is more likely some nuance within CUCM. Your CUCM does not know how many DSPs the router has, and if you try to configure too many it will outright reject it instead of giving you minimal channels.

I would start resetting parts of your CUCM to see if it helps - TFTP service, Callmanager service, reset the gateway, etc.

You can always stop the autoconfig:

no ccm-manager config


bigcappa1 Tue, 07/28/2009 - 00:16


I agree changing the channels is not a DSP issue. What the issue is when I installed the FXO card it used up 12 DSPs on the 1st DSP slot, as a result the channels in the E1 config which used this DSP originally reduced from 31 to 19. Before I installed the FXO both E1 channels on my gateway displayed using 30 channels

controller E1 0/0/0

pri-group timeslots 1-31 service mgcp


controller E1 0/0/1

pri-group timeslots 1-31 service mgcp

Added the FXO and the first E1 dropped to 19 channels

What I then noticed and this is why I suspected the DSP allocation issue, not a an actual dsp issue is that the FXO took the first 12 DSPs from DSP1 where as this was originally what was used for the first E1.

I am upgrading the IOS from a 12.4.15 train to 12.4.22 so will see if this helps if not will log a ticket.

Thanks for your reply thoug



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