[Asterisk-Users] Maximum tollerable lag/jitter for IAX2 w/ojitterbuffer enabled?

[Chris Shaw]

----- Original Message -----
From: "Kris Boutilier" <Kris.Boutilier at scrd.bc.ca>
To: "Asterisk Users Mailing List - Non-Commercial Discussion"
<asterisk-users at lists.digium.com>
Sent: Tuesday, September 07, 2004 4:26 PM
Subject: [Asterisk-Users] Maximum tollerable lag/jitter for IAX2
w/ojitterbuffer enabled?


> I'm having a problem with intersite calls over IAX2 being abruptly
> terminated. Nothing odd shows in any of the logs for Asterisk or the host.
> The only think I can think it might be is a lag-spike on the site to site
> connection.
>
>  How sensitive is IAX2 to lost frames, lag spikes or large variations in
> jitter with the GSM codec and:
>
>  bandwidth=low
>  jitterbuffer=no
>  trunkfreq=100 ; Raised from 20
>  tos=lowdelay
>
>  notransfer=no
>  trunk=no
>
> All calls are running as GSM, even though g.729 is also an 'allowed' codec
> (w/5 licenses installed). During an average call 'iax2 show channels'
> provides:
>
> Peer             Username    ID (Lo/Rem)  Seq (Tx/Rx)  Lag      Jitter
> JitBuf  Format
> 10.0.40.140      astpbx-woo  00002/00002  00005/00006  00040ms  0036ms
> 0000ms  GSM
>

If you can reproduce it, this smells like a bug... IAX runs over TCP and TCP
doesn't just disconnect sockets unless it recieves a RESET or a FINISHED or
there's a timeout (usually like 5 minutes or more depending on your TCP/IP
stack). Needless to say that to disconnect a TCP connection, that would have
to be one hell of a lag spike... * must be actively disconnecting the
connection....

I've heard the jitter buffer is a bit buggy, have you tried turning it off
completely?

Hell even SIP won't just disconnect you unless your UA tells it to do so...

    -Chris