[Asterisk-Users] "Glare" condition - How well does asterisk handle?

[Storer, Darren]

Hi Scott,

SS> Normally PBX's are designed to have the CPE yield to an incoming
SS> call if a particular channel is seized by both ends at the same
SS> time (a condition known as "glare"), but I'm wondering if anyone
SS> has real-world experience with asterisk to say how well this is
SS> handled.

Earlier this year I had experience of this scenario in a UK carrier and in
the end I opted for split working with the top 10 channels of the PRI
dedicated for outbound traffic. Admittedly the platform may have been a
little under specified for the job (E100P installed in an HP 1U PIII 750MHz
Rack Server) but I was surprised that it could not cope with the contention
on a single E1. The symptoms were loss of channels and excessive alarms from
the public switch during peak traffic resulting in the need to reset the PRI
from the public switch console and a quick 'init 6' for the * machine.

The problem was captured on an MPA, I'm hoping to find a copy of the trace
to share with the list. From memory it appeared that * stopped responding to
some messages from the switch which left channels in an unknown state. The
CPU was occasionally busy so perhaps the poor signalling was related to CPU
load and timing constraints.

I'll post the trace when it surfaces...

HTH

Darren
--
Comgate
Telco>Internet<Broadcast
Tel: +44(0)700 COMGATE

-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com]On Behalf Of Scott Stingel
Sent: 25 May 2004 19:54
To: asterisk-users at lists.digium.com
Subject: [Asterisk-Users] "Glare" condition - How well does asterisk
handle?


Hi-

I have an upcoming application that requires use of PRI channels that are
primarily used for high-volume incoming traffic, but that are to be used for
outbound calling as well.  Of course, one option is to have dedicated
outbound channels reserved, but this is an inefficient use of channel
resources.

Normally PBX's are designed to have the CPE yield to an incoming call if a
particular channel is seized by both ends at the same time (a condition
known as "glare"), but I'm wondering if anyone has real-world experience
with asterisk to say how well this is handled.

Thanks
Scott Stingel

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


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