[Asterisk-Users] IAX Jitter

[Rich Adamson]

> 
> I have a question regarding IAX jitter. I have 3 users on a LAN dialing into a Meetme 
conference on an Asterisk box which is also hosted on
> the LAN. I have set jitterbuffer = no and tos = lowdelay. Now, for 2 of the users the audio is 
fine, but for the 3rd user there is intermittent break
> up in the audio when they are receiving. I have had a look at 
iax2 show channels
 and for the 
first 2 users (those with no audio problems),
> the Jitter is low (0006ms), and the Lag is relatively high (00070ms). For the 3rd user (the 
one with audio breaking up), the Jitter is relatively high
> (0627ms) and the Lag is relatively low compared to the others (00012ms).
> 
>  
> 
> All of the users are on the same LAN, so cant quite understand the differences.
> 
>  
> 
> Any explanations / ideas would be much welcome.

Almost sounds like a half vs full duplex misconfiguration with the
third PC. In other words, the PC might have negotiated a full duplex
nic interface while its switch port negotiated a half duplex. The
mis-match will have a significant impact.

If its a managed switch, define the PC's port as full-duplex and do
the same on the PC's nic card. If its unmanaged, play around with
the PC's nic card definition (half vs full vs auto) to see if that
impacts the issue. 

If there are multiple switches involved, also check the duplex settings
on the switch to switch link.