[Asterisk-Dev] Recent PRI load problem

[Scott Stingel]

Hello-
 
I attempted last week to update to the latest CVS for my customer in
Portugal, in order to take advantage of some new available features.  (I
have 5 systems running high-volume IVR, each with 4 E1 spans).
 
In this process, I found that since March 25 (when I last had a version that
passed any kind of load test), the PRI driver or related code has been
changed, with the result that it can no longer handle load without
constantly taking the PRI D-channels down and up.  This of course results in
many lost calls.  I can make this happen with my load tester quite easily -
it only takes 10 or more simultaneous PRI calls, and happens within 60
seconds.
 
The first error I get is:
 
May 13 09:59:02 WARNING[-1200182352]: chan_zap.c:6134 zt_pri_error: PRI: ACK
received outside of window, restarting
  == D-Channel on span 2 down
 
Followed by many I-frame and S-frame errors that result from the link being
down.
 
I'm trying to narrow down the date and changes made to the chan_zap and
related code during April so that I can zero in on the error or bug.  If
anyone has changed the PRI driver code recently (April probably), could you
please contact me or post here for discussion?  I'm trying to gather more
info before posting this on the bug list.
 
Thanks!
Scott Stingel
 
PS:  My load tester loops back a designated number of channels on PRI 2 to
PRI 1, and PRI 4 to PRI 3.  It generates calls on channels on the even PRI
spans and receives them on the odd spans.  The receiving dialplan simply
answers, plays a message and hangs up.  I have used this software and
loopback configuration successfully for about a year now in helping to flush
out bugs and limitations of the drivers and hardware.
 

 
 
Scott M. Stingel
President,
Emerging Voice Technology, Inc.
Palo Alto California & London England
www.evtmedia.com