[Asterisk-Users] Excessive VNAK's and jitter over IAX2

[Adam Hart]

I'm also getting this issue, for some reason some calls yield mass VNAK's. I
also get iseq problems, but that might be my code - eg

DEBUG[98311]: File chan_iax2.c, Line 4368 (socket_read): Received iseqno 4
not within window 0->2
DEBUG[98311]: File chan_iax2.c, Line 4368 (socket_read): Received iseqno 4
not within window 0->2
DEBUG[98311]: File chan_iax2.c, Line 4368 (socket_read): Received iseqno 4
not within window 0->2

Both happen in 5% of the time.

----- Original Message ----- 
From: "Matt Lawson" <matt at 1control.com>
To: <asterisk-users at lists.digium.com>
Sent: Friday, December 19, 2003 7:59 AM
Subject: [Asterisk-Users] Excessive VNAK's and jitter over IAX2


> Howdy,
>
> I recently saw something strange with a call between  *'s over IAX2.
>  There are actually 3 *'s involved.  The setup is like this:
>
> SIP phone ------(ulaw over LAN)------ *1 -------- IAX2 (ulaw over
> Internet) ---------*2--------(GSM over Internet)
> -----------*3--------(ulaw over LAN)------ SIP phone
>
> Now what is shown below is the Asterisk in the middle, that is doing the
> conversion between the other two, one of which only speaks ulaw and the
> other only speaks GSM.
>
> The call basically seemed to work, except the audio quality was
> terrible, but it did seem to be basically connected.  Asterisk started
> spewing out these VNAK messages, thousands of them as fast as it could.
>  In the middle of it I did an "IAX2 show channels" to show what was in
> progress.
>
> The asterisk version shown here is a completely stock, CVS version from
> just a few days ago.  The "outboard" Asterisks are somewhat modified but
> also re-synchronized with CVS within the last week.
>
> Also, all Asterisks have iax jitterbuffer=no.
>
> So, my questions are:
>
> 1.  What do the excessive VNAKs indicate?  Some type of communication
> error?  NAT-related perhaps?
> 2.  Does the 20,000+ jitter have something to do with the audio sounding
> terrible?
> 3.  Why is there jitter at all if all Asterisks have their IAX2 jitter
> buffers turned off?
> 4.  Is there any significance to the "Username (none)" for one of the
> peers?  The Asterisk has both peer and user names for both machines.
>  The caller name shows up, but the callee name is always "(None)"
>
> Ideas anyone?  Thanks.
>
>
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending
> VNAK
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending
> VNAK
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending
> VNAK
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending VNAK
>
> s
>
> Peer             Username    ID (Lo/Rem)  Seq (Tx/Rx)  Lag      Jitter
> Format
> 24.9.xx.xxx      i58         00009/00003  00015/00006  00000ms  0169ms
> ULAW
> 66.167.xx.xxx    (None)      00010/00004  00008/00013  00009ms  20743ms
> GSM
> 2 active IAX
> channel(s)
>
> *CLI> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending
> VNAK
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending
> VNAK
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending
> VNAK
> DEBUG[98311]: File chan_iax2.c, Line 4649 (socket_read): Sending VNAK
>
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