[Asterisk-Users] RED ALARM on PRI channel takes Asterisk DOWN

[Peter Svensson]

On Thu, 5 May 2005, Vikram Rangnekar wrote:

> what i noticed is that when i pull any one end of the E1 (breaking the E1
> connection) I get multiple RED ALARMS on the zap channels I understand this
> is ok and should happen if the E1 link breaks but my problem is that asterisk
> stops doing a lot of other things too like i have extensions configured to
> meetme, voicemail and other aplications they all stop working i get no
> sound but when i call one hardphone to another it works i guess thats cause
> the rtp streams go from phone to phone directly. but why does asterisk stop
> passing anything through itself. Also if anyone else has experience this is
> this only with sangoma or does it happen with asterisk too. I have a digium
> card but its a single port and i dont have a real E1 link to test with. )

All the things mentioned above that stop working when the E1 is 
disconnected require zaptel clocking. Zaptel clocking is normally derived 
from the E1 clock, or may be generated internally by a zaptel card. 

My guess is that the Sangoma card does not switch to internal clocking 
when the external clocking is lost, thus depriving Asterisk of the zaptel 
clock source that drives a lot of the internal transmissions. 

You may be able to compensate by having the ztdummy module loaded. Doing 
so may cause problems. I have never tried having both real zaptel drivers 
loaded at the same time as ztdummy.

Peter