Sep 16

One way calling over Cisco Voice Gateway using MGCP PRI

Had an issue where a site was not able to dial local numbers over their local PRI on their MGCP (Cisco) Gateway. Inbound calls worked from the PRI. I found that the PVDM had a bad DSP on it. The DSP was the DSP that converted the local IP packets into the protocol for the PRI.

After replacing the PVDM, the local calls started working.

Here is how to tell if a DSP has failed.
Issue the following command on the router, you will notice DSP 1 & 2 are good and 3 is bad.

show voice dsp group all

MR.BEERĀ®

GoatRouter#show voice dsp group all
DSP groups on slot 0:
dsp 1:
State: UP, firmware: 24.3.7
Max signal/voice channel: 16/16
Max credits: 240
num_of_sig_chnls_allocated: 16
Transcoding channels allocated: 1
Group: FLEX_GROUP_VOICE, complexity: FLEX
Shared credits: 210, reserved credits: 0
Signaling channels allocated: 14
Voice channels allocated: 0
Credits used: 0
Group: FLEX_GROUP_XCODE, complexity: MEDIUM
Shared credits: 0, reserved credits: 30
Transcoding channels allocated: 0
Credits used: 0

dsp 2:
State: UP, firmware: 24.3.7
Max signal/voice channel: 16/16
Max credits: 240
num_of_sig_chnls_allocated: 16
Transcoding channels allocated: 3
Group: FLEX_GROUP_VOICE, complexity: FLEX
Shared credits: 150, reserved credits: 0
Signaling channels allocated: 10
Voice channels allocated: 0
Credits used: 0
Group: FLEX_GROUP_XCODE, complexity: MEDIUM
Shared credits: 0, reserved credits: 90
Transcoding channels allocated: 0
Credits used: 0

dsp 3:
State: FAIL, firmware: 0.0.0 —————-> This DSP has failed
Max signal/voice channel: 16/16
Max credits: 240
num_of_sig_chnls_allocated: 1
Transcoding channels allocated: 0
Group: FLEX_GROUP_VOICE, complexity: FLEX
Shared credits: 240, reserved credits: 0
Signaling channels allocated: 1
Voice channels allocated: 0
Credits used: 0

If you had one way calling on your PRI, was this your problem or something else?

May 05

OSPF is not using the best route

If you are finding that OSPF is not using the fastest links on your network, it probably sees your 100mbps, 1G, and 10G interfaces as the same cost, 1. To get more granular route selection from OSPF, you need to change your reference-bandwidth statement. You want your highest bandwidth interface to have a cost of 1. If you uses 10,000 in the statement below, it would give your 10G interfaces a cost of 1.

**YOU MUST ADD THIS COMMAND TO EVERY ROUTER RUNNING OSPF IN YOUR NETWORK**

In Router Configuration mode use the following command

auto-cost reference-bandwidth

= The largest bandwidth interface, Example, 10G interface would be 10000

The statement above works for both Brocade and Cisco.