[Asterisk-Users] iaxtel and jitterbuffer

[Michael George]

On Sat, Aug 28, 2004 at 08:39:50AM -0600, Rich Adamson wrote:
>  
> I do a lot of work with companies throughout the US on network performance
> and we _frequently_ run into routers, switches, servers, etc, that are
> allowed to auto-negotiate their half vs full duplex nic interfaces. About
> 50% of the time, systems will get it wrong as there are no standards as
> to how the negotiation should be done.
> 
> A recent case this past week indicated that data flow between two servers
> on the same layer-2 network was around 400 kbps when it should have been
> able to sustain at least 80 meg.
> 
> You might double check each of your ethernet interfaces to ensure duplex
> settings are correct. If not at full duplex all the way through, you'll
> run into the strangeness you're seeing under varying traffic loads.

My ISP has a half-duplex connection between me and the world-at-large.  It
doesn't seem like that should be a problem, though, because we've been running
VOIP with Multitech proprietary hardware for over two years now with little
trouble and excellent voice quality.  That was using a 9.6KBps codec.

The difference between that and what I'm getting from IAX/GSM is profound,
with GSM being intolerably poor quality.

As a test, I ran two internal * machines with IAX/GSM between them.  A
conversation would consume from 7-10KBps, varying.  Then I would call Digium's
iaxtel number and I could see traffic from 4.5-8KBps and the voice was all
choppy.  I called another person's system (knowing they had IVR, of course)
and the audio was also choppy, but when it got through the message and sent
ring tones, they sounded fine.  Then another voice message and it was choppy
again.

So I tried digium again.  This time I could see the bandwidth being consumed,
but I heard nothing on the line at all.

So I tried calling my own iaxtel number.  I could see my badwidth usage jump
to about 10KBps, as I would expect and * told me that it was playing out the
appropriate audo to the "incoming caller".  I heard nothing, however.

Does this perhaps give any further indication of what might be wrong?

I have in my [general] section:
	bandwidth=low
	disallow=all
	allow=gsm
	jitterbuffer=yes
	dropcount=10
	maxjitterbuffer=500
	maxexcessbuffer=100 
	minexcessbuffer=10
	jittershrinkrate=1
	trunk=no
	register => mxxxxxxxxxxxxe:yyyyyyyyyyy at iaxtel.com
	tos=lowdelay

I'm working towards a client install of IAX which will be used for
inter-office VOIP, but I need to get this issue worked out or it's not
deployable.

-- 
-M

There are 10 kinds of people in this world:
	Those who can count in binary and those who cannot.