asterisk users - Apr 2009 - what can we do with lost voice packet on a congestioned VPN?

Hi to all
in a scenario where:

- the bandwith is shared with other traffic (HTTP,VPN,ecc)
- the PBX is on a remote VPN peer
- due to many reasons Qos is not usable

There is a IAX trunk between 2 Asterisk 1.4 i've tried different
codecs (ulaw,alaw,gsm) but the main problem still remain the same: too
many voice packet get lost.

The main problem is surely on the network, but the strange thing is
that on the same network there is an H323 trunk from an Alcatel and a
Cisco CCM (using g711 codec) and in that case the voice isn't so bad!

i've tried to enable jitterbuffer but i can't notice some difference.

Is there something else that i can do?

Thanks to all

-- 
/*************/
nik600
http://www.kumbe.it

nik600 wrote:
> Hi to all
> in a scenario where:
> 
> - the bandwith is shared with other traffic (HTTP,VPN,ecc)
> - the PBX is on a remote VPN peer
> - due to many reasons Qos is not usable
> 
> There is a IAX trunk between 2 Asterisk 1.4 i've tried different
> codecs (ulaw,alaw,gsm) but the main problem still remain the same: too
> many voice packet get lost.
> 
> The main problem is surely on the network, but the strange thing is
> that on the same network there is an H323 trunk from an Alcatel and a
> Cisco CCM (using g711 codec) and in that case the voice isn't so bad!
> 
> i've tried to enable jitterbuffer but i can't notice some
difference.
> 
I think if you have packet loss, a jitterbuffer would make no difference..
SOmething like PLC (packet loss concealment maybe ?) come to mind ?

Have you tried ILBC ? or SPEEX ? G.711 should be resilient, but I 
understand iLBC and Speex both have some tricks to handle PLC.
Also, GIPS had some kind of magic sauce they offered (code-wise) to 
offer PLC to vendors ??
> Is there something else that i can do?
> 
> Thanks to all
>

I wonder if using the "Internet Low Bit Rate Codec" or iLBC would work
better.  G711/G279/GSM all suffer when too many packets are lost. You
would then need to transcode to G711, etc -jason

http://en.wikipedia.org/wiki/Ilbc



-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of nik600
Sent: Sunday, April 05, 2009 3:43 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [asterisk-users] what can we do with lost voice packet on
acongestioned VPN?

Hi to all
in a scenario where:

- the bandwith is shared with other traffic (HTTP,VPN,ecc)
- the PBX is on a remote VPN peer
- due to many reasons Qos is not usable

There is a IAX trunk between 2 Asterisk 1.4 i've tried different
codecs (ulaw,alaw,gsm) but the main problem still remain the same: too
many voice packet get lost.

The main problem is surely on the network, but the strange thing is
that on the same network there is an H323 trunk from an Alcatel and a
Cisco CCM (using g711 codec) and in that case the voice isn't so bad!

i've tried to enable jitterbuffer but i can't notice some difference.

Is there something else that i can do?

Thanks to all

-- 
/*************/
nik600
http://www.kumbe.it

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