asterisk users - Apr 2005 - Should PRI running over t100p be able to survive short yellow alarms?

I have a PRI connection between Asterisk and a PBX. The connection passes
through a hardware echo canceller which includes some monitoring facilities.
Occasionally the T1 has gone yellow for short periods (<2 seconds) and when
this occurs Asterisk seems to immediately tear down any in-progress calls. Is
this expected behavior or should the established B-channels stay up (sans audio)
until the T1 either goes red or a longer period of time (say > 10 seconds)
passes?

I appreciate the best solution would be to fix the cause of the intermittant
yellow alarms, however I am curious...

Thanks.

Kris Boutilier
Information Services Coordinator
Sunshine Coast Regional District

On Tue, 5 Apr 2005, Kris Boutilier wrote:
> I have a PRI connection between Asterisk and a PBX. The connection
> passes through a hardware echo canceller which includes some monitoring
> facilities. Occasionally the T1 has gone yellow for short periods (<2
> seconds) and when this occurs Asterisk seems to immediately tear down
> any in-progress calls. Is this expected behavior or should the
> established B-channels stay up (sans audio) until the T1 either goes red
> or a longer period of time (say > 10 seconds) passes?
Well, a yellow alarm is a remote alarm. When someone is sending a yellow 
alarm they are usually considering the link to be down. Are you sure 
there are any calls left active by the remote side when the yellow alarm 
clears?

Peter

Kris Boutilier wrote:
> I have a PRI connection between Asterisk and a PBX. The connection passes
through a hardware echo canceller which includes some monitoring facilities.
Occasionally the T1 has gone yellow for short periods (<2 seconds) and when
this occurs Asterisk seems to immediately tear down any in-progress calls. Is
this expected behavior or should the established B-channels stay up (sans audio)
until the T1 either goes red or a longer period of time (say > 10 seconds)
passes?
> 
> I appreciate the best solution would be to fix the cause of the
intermittant yellow alarms, however I am curious...
Check your Zaptel card timing setting.  i.e. span=1,1,0,esf,b8zs in 
/etc/zaptel.conf.  The second "1" on the line says "get timing
for T-1
frames FOR THIS CARD from the other end of the T-1"

I have a problem where I have two T-1s from our provider and I'm getting 
the frame timeing from T-1 #1.  T-1 #2 every once in a while goes into 
yellow alarm for a very short time.  There's nothing I can do about it 
because I'm using a 4-port Digium card and there's only one timing 
source per card.