[asterisk-users] Purpose of qualify=yes

[Peder]

qualify=2000 does not mean it sends a qualify every 2000ms, 2 seconds.  It
means that the qualify timeout is 2000ms, so if it receives a response at
2600ms, it counts that phone as down.  I believe the timing of qualifies is
still every 60 seconds, unless explicitly changed by the system admin:

http://www.voip-info.org/wiki/view/Asterisk+sip+qualify

So 20 phones with qualify is 40 packets/minute (1 packet out and 1 packet in
per phone).

I've always liked qualify as it lets me know if a phone is alive or not,
even in non NAT scenarios.  If someone calls in and says "my phone doesn't
work", I can check the qualify and if it shows it down, have them reboot.
If it shows up, then I debug them trying to place a call.  It is just easy
extra help in troubleshooting.



-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Chris Owen
Sent: Thursday, September 16, 2010 11:02 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] Purpose of qualify=yes

On Sep 16, 2010, at 10:45 AM, Zeeshan Zakaria wrote:

> I prefer to keep qualify=on for all the extensions, as it gives you an
idea which extensions are going to give you trouble. For extensions with
qualify value greater than 300 ms you should definitely worry. For
extensions at 2000ms delay or more, turning qualify off simply means to
ignore the obvious problem. Such extensions have communication or network
issues which require serious attention. You can set this parameter to, e.g.
3000 ms or more if dealing with 2000 ms delay is unavoidable, but don't turn
it off. Afterall even at 2000 ms conversation is not truly real time and not
easy.

In our case the problem isn't that the phones are experiencing high latency
per se but rather than a full pipe plus all these SIP messages is playing
hell with the QOS stuff.

20 phones in one location times say 4 SIP packets every 2 seconds equals 40
SIP packets a second.   That normally isn't a problem but when the pipe gets
congested then we start seeing issues when a call comes in and 400 BLF
notices go out etc.  Obviously we can increase the amount of bandwidth
reserved for SIP traffic but I'm just not sure why we're sending all those
packets in the first place.

In other words, the qualify traffic is actually causing the problem, not
revealing it.

Chris



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