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New Member

CCM Trace to troubleshoot D-channel out of service?

Hello Experts,

I received an alert that a d-channel was out of service on our WDC gateway. I was hoping a ccm trace could provide me some insight as to why (is channel flapping, did gateway unregister and why?) I found a trace file that might help but I guess I still don't know enough about what I'm supposed to be looking for. (Don't speak the language too fluently). This happens once in a while and I don't have enough knowledge to explain the why to inquiring minds. If anyone had a couple of moments to help me decipher I'd be grateful!

The original alerts:

At 01:25:41 on 02/23/2010 on cluster StandAloneCluster. MGCP DChannel is out-of-service . The following gateway device(s) have D-Channel-Out-Of-Service status: S0/SU1/
At 01:26:12 on 02/23/2010 on cluster StandAloneCluster. Number of registered gateways decreased . Current monitored precanned object has decreased by 9.

I'm assuming because of the timeframe the gateway decreased is the same one referenced in the D-channel alert, but RTMT doesn't provide detail in that alert.

In this trace I searched for which is ip addy of above gateway...I see the first hit for that at a 01:25:12.783 timestamp.

As always thank you thank you!



Re: CCM Trace to troubleshoot D-channel out of service?

Excellent work looking at the CUCM trace,

for thse type of cases I suggest to check 3 places:

PSTN side

GW - CUCM side


You can collect debugs to see if Interface itself is flapping

which IOS ?

What is the topology

CUCM version?

When this happens do you see any alarm in IOS GW?

I opened the trace but was unable to find the alarm


New Member

Re: CCM Trace to troubleshoot D-channel out of service?

Thank you for your guidance. This happened again early this morning.

Remote GW IOS is 12.4(15)T8 located in WDC

We have MPLS WAN link connecting both locations (3rd party managed router on each side)

Call manager version is 4.2(3)

Where can I check for alarms on the IOS GW? I am attaching contents of log buffer on GW.

Also when I do a sh ccm-manager on GW i see following:

Last failover time:             06:00:16 EST Mar 1 2010 from
Last switchback time:           06:00:28 EST Mar 1 2010 from
Switchback mode:                Graceful
MGCP Fallback mode:             Enabled/OFF
Last MGCP Fallback start time:  06:00:44 EST Mar 1 2010
Last MGCP Fallback end time:    06:01:01 EST Mar 1 2010

What scenario causes this failover and switchback? Does this happen if the PRI unregisters?

Forgive my ignorance, but could you help explain what you mean by

"PSTN side" and "GW-cucm side"?

Thanks for your patience,