Trunk errors on the NetVanta 644

[Anonymous]

Hello,

What would cause the following errors:

2012.08.09 08:21:42 TM.T02 0 IsdnTrunkManager::getIsdnChannel - TA = 19, IsdnChannel is NULL

2012.08.09 08:21:42 TM.T02 20 IsdnTmStateIdling - clear trunk appearance

2012.08.09 08:21:42 SB.CALL 178033 RTP resource unavailable or SDP negotiation failed. Call from (XXXXXXXXXX) to (XXXXXXXXXX).

These errors happened while the call was coming out the PRI routing to a VoIP gateway.

This call never reach the VoIP gateway (verified by a packet trace that I keep running).

Any help will be greatly appreciated.

Thank you,

[Anonymous]

Unified,

We may have a B channel allocation or resource issue of some kind.  I would first verify that both sides of the PRI are set to use the same number of B channels.  If you set the resource selection to circular, can you determine if the failures only occur when specific B channels are requested?  We would likely need to see the following debug output for a given test call.

debug voice verbose

debug isdn L2-formatted

debug sip stack message

Thanks!

David

[Anonymous]

Hi David,

I have thousands of calls going through the 644 daily.

This only happened once.

[Anonymous]

unified,

With that call volume, we bring in the possibility both systems trying to access the same B channel at the same time.  This is typically called glare.  The best prevention is to make sure that each device prefers a different end of the B channels.  In Adtran CLI syntax, this would be "resource-selection linear ascending" on one unit and "resource-selection linear descending" on the other side of the PRI.  Given this configuration, the potential for glare really only exists when there is only one free B channel. 

If you get a complete debug capture, we would be glad to take a closer look.

Thanks,

David

[Anonymous]

This is only being used for inbound traffic (from PRI to SIP) so I doubt it will a glare issue.

Since It only happened once my guess is that it was a fluke.

[Anonymous]

unified,

I'm going to go ahead and mark this post as "assumed answered".  However, if you continue to have any problems we would be glad to take a closer look at debug output.  Just let us know if we can help out.

Thanks!

David