Calls randomly dropping

[uclarryh]

Topology:

PSTN_PRI >> ADTRAN>>PRI to Cisco_2821 >> MGCP_CUCM

Recently users have been complaining of calls dropping. I checked my CUCM server traces as well as the MGCP gateway and everything appears fine; however, when I check the logs on the ATALS 550 it appears that the PRI connected to the PSTN is going up/down. I contacted the carrier who stated that everything is running clean on their side. Any ideas

05/31 11:28:57 Min T1     Ntw1    1 T1 Blue Alarm Active
05/31 11:28:58 Maj T1     Ntw1    1 T1 Red Alarm Active
05/31 11:28:58 Maj T1     Ntw1    1 T1 Tx Yellow Alarm Active
05/31 11:28:59 Maj T1     Ntw1    1 T1 D Channel Alarm Active
05/31 11:29:02 Min Syste            Timing Source Changed to Back up
05/31 11:29:06 Min T1     Ntw1    1 T1 Blue Alarm Cleared  
05/31 11:29:07 Maj T1     Ntw1    1 T1 Tx Yellow Alarm Cleared 
05/31 11:29:07 Maj T1     Ntw1    1 T1 Red Alarm Cleared       
05/31 11:29:07 Maj T1     Ntw1    1 T1 Curr UAS Thrs Exceeded
05/31 11:29:08 Maj T1     Ntw1    1 T1 D Channel Alarm Cleared

05/31 11:47:17 Min T1     Ntw1    1 T1 Blue Alarm Active
05/31 11:47:18 Maj T1     Ntw1    1 T1 Red Alarm Active
05/31 11:47:18 Maj T1     Ntw1    1 T1 Tx Yellow Alarm Active
05/31 11:47:19 Maj T1     Ntw1    1 T1 D Channel Alarm Active
05/31 11:47:22 Min Syste            Timing Source Changed to Internal
05/31 11:47:26 Min T1     Ntw1    1 T1 Blue Alarm Cleared
05/31 11:47:27 Maj T1     Ntw1    1 T1 Red Alarm Cleared
05/31 11:47:27 Maj T1     Ntw1    1 T1 Tx Yellow Alarm Cleared
05/31 11:47:27 Maj T1     Ntw1    1 T1 Curr UAS Thrs Exceeded
05/31 11:47:28 Maj T1     Ntw1    1 T1 D Channel Alarm Cleared
05/31 11:47:30 Maj ISDN   Ntw1    1 D channel is DOWN
05/31 11:47:31 Min Syste            Timing Source Changed to Primary

[Anonymous]

From your log, it appears the problem is on the PRI connected to the ATLAS' Network 1 module. The ATLAS is receiving a BLUE alarm on this module, which is un-framed all ones (sometimes called AIS). The ATLAS is receiving this BLUE alarm, and because it is un-framed, it also causes a RED alarm (loss of frame). I'm assuming Network 1 is PRI from the carrier, since a BLUE alarm is an alarm from the network. Each BLUE alarm in this log only lasts for 9 seconds, but it is a received alarm.
I suggest you go back to the carrier and inform them that you are receiving BLUE alarms and have them investigate why they are sending these alarms.

If you want to verify the ATLAS ports, you can either reconfigure the ports so you can swap the ports connecting to the carrier and the Cisco, or if they are both Network Modules, you can physically swap the modules, but leave the carrier PRI and the Cisco PRI connected to either Ntwk1 or Ntwk2. (So Ntwk1 will have the module that was in Ntwk2 and Ntwk2 will have the module that was in Ntwk1). If the problem follows the module, then you have a bad module.

Hope this helps. Let us know what you find out,

Patrick

[uclarryh]

Hi Patrick,

I appreciate your response. In an effort to determine if the issue is carrier related, I bypassed the Adtran and connected the PRI directly to the Cisco 2821 router. I am currently monitoring the router to see if the problem recurs. If so, I believe it's safe to assume the problem is either physical 'cabling' or carrier related. If not, I would suspect a problem with the Adtran port. I’ll continue to update this discussion as the issue progresses. Again thanks for the reply.

[uclarryh]

After days of troubleshooting and fingerpointing, we finally found what I suspected to be the case all along. It was a carrier issue!!!

[Anonymous]

Sorry it was so difficult to work out, but it looked like a carrier issue from the start. I'm glad you were finally able to get it resolved. I'll go ahead and mark this discussion as resolved.