[Asterisk-Users] PRI D-channel signalling error? "Ring requestedonchannel 0/1 a lready in use on span 1. Hanging up owner."

[Ben Merrills]

This was happening to me a week or so ago. The problem came from the
fact calls were being hungup on, however, asterisk (or zaptel/libpri)
said not. The system thought the channels were still open, and so
collisions started to occure.

I recompiled zaptel and libpri and installed them again (from cvs).

Hope this might help you,

Ben 

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Peter
Svensson
Sent: 29 September 2004 08:23
To: dboyd at fullmoonsoft.com; Asterisk Users Mailing List - Non-Commercial
Discussion
Subject: RE: [Asterisk-Users] PRI D-channel signalling error? "Ring
requestedonchannel 0/1 a lready in use on span 1. Hanging up owner."

On Tue, 28 Sep 2004, David Boyd wrote:

> > -----Original Message-----
> > From: asterisk-users-bounces at lists.digium.com
> >
> > Can anyone shed some light on "Ring requested on channel 0/1 already

> > in use on span 1.  Hanging up owner."? This is happening two or 
> > three times a day on a span with about 500-600 calls per day. The 
> > remote device is a PBX, connected by a crossover cable and protocol 
> > is DMS-100.
> 
> Sounds like it could be glare, is the span two way?

The q931 specification (5.7) seems to say that there can be a conflict
of channels, if both the cpe and the net selects the same B channel for
one call each at the same time. I guess this can be prevented if the cpe
allows the net to select the B channel for the outgoing calls (Any
Channel Acceptable).

Barring that, a contention can occur and is handled by the cpe side
clearing its still unconnected call. The cpe side could retry the call
on a different B channel at that point.

>From q very quick look at chan_zap and the messages from a pri intense
debug it seems that Asterisk selects a B channel and requests that
particular channel from the net. 

For the normal isdn configuration (the net hunts from low channels, the
cpe hunts from high channels) there should rarely be a collision unless
the trunk is close to saturation, in which case congestion _is_ the
correct result.

Peter

_______________________________________________
Asterisk-Users mailing list
Asterisk-Users at lists.digium.com
http://lists.digium.com/mailman/listinfo/asterisk-users
To UNSUBSCRIBE or update options visit:
   http://lists.digium.com/mailman/listinfo/asterisk-users