OOS b-channel

Unanswered Question
May 5th, 2009
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On my syslog I notice this kind of error on E1 b-channel:


I also notice that:

- I have an OOS b-channel from Real Time Monitoring Tool.

- if I disconnect the E1 cable from the router and then I connect the cable, the b-channel becomes idle

Reading the Cisco documentation it is recommended to contact the TAC.

Meanwhile anyone could help me?



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Overall Rating: 5 (1 ratings)
murabi Mon, 05/11/2009 - 11:55
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The explanation for your syslog message is " The B-channel indicated by this alarm has gone out of service. Some of the more common reasons for a B-channel to go out of service include: Taking the channel out of service intentionally to perform maintenance on either the near- or far-end; MGCP gateway returns an error code 501 or 510 for a MGCP command sent from Cisco Unified Communications Manager (Unified CM); MGCP gateway doesn't respond to an MGCP command sent by Unified CM three times; a speed and duplex mismatch exists on the Ethernet port between Unified CM and the MGCP gateway"

Recommended action:

Check the Unified CM advanced service parameter, Change B-channel Maintenance Status to determine if the B-channel has been taken out of service intentionally; Check the Q.931 trace for PRI SERVICE message to determine whether a PSTN provider has taken the B-channel out of service; Reset the MGCP gateway; Check the speed and duplex settings on the Ethernet port.


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