[Asterisk-Dev] PRI/Zap

[Peter Svensson]

On Wed, 4 May 2005, Andrew Kohlsmith wrote:

> On May 4, 2005 12:25 pm, Steven wrote:
> > That is configurable. In fact, it was a question we received while
> > ordering our channelized T1 if we wanted round robin ascend/descend or
> > in order ascend/descend. Don't seem to remember it with out PRI, but I'm
> > sure it is an option as well.
> 
> No, I realize practically everything's configurable...  I'm just saying it 
> seems that most times this is how the channel allocations are done.
> 
> In fact, doing it this way (always starting at the lowest/highest) is probably 
> less likely to cause glare.

The q.931 standard recomend that the net end should hunt low to high and
the cpe end should hunt high to low. This is exactly to reduce the
likelyhood of both ends sending setup messages with the same channel at
the same time.

However, asterisk should ideally allow the net end to select the B
channel, or at least understand and retry the setup message when a
"selected B channel rejected" reply arrives.

Peter