[Asterisk-Users] TDMoE and codecs

[Steven Critchfield]

On Wed, 2003-09-10 at 14:39, James Sharp wrote:
> > If the remote ends can do the codec, then yes. If they can't deal with
> > the incoming codec, then it will be done at your h323 end point. The
> > benefit of IAX2 trunking is to cut down on your ethernet load and to
> > make expanding easier. Not to mention IAX2 is much better tested than
> > TDMoE.
> 
> Can the IAX2 trunking do the equivalent of "groups" in Zaptel?  What I'm
> needing to do is take a whole bunch of H.323 incoming calls and spread
> them out across many T1s (more than what would go into a single machine).

Trunking does combining of control data and audio data into a single
packet so there are fewer packets on the wire. Every TCP/IP packet has a
minimum of 40 bytes of header data. If you can pack the packet full, or
at least to the MTU, you save a few 40 byte sections here and there. As
you approach your bandwidth limit, little things like this help. But,
no, it doesn't do the same as "groups"

> I suppose I could do something like this in extensions.conf
> 
> [incomingh323]
> 
> exten => s,1,Dial(IAX2/foo:foo at machine1.psychoses.org)
> exten => s,102,Dial(IAX2/foo:foo at machine2.psychoses.org)
> exten => s,203,Dial(IAX2/foo:foo at machine3.psychoses.org)
> etc etc etc
> 
> 
> And then us Dial(Zap/g1) on each of the machines in the incomingiax context.

This would work, and has the added benefit of doing fail over if you
decide to take down a machine for maintenance.

> Then I just have to put a G.729 codec on each of the remote machines to
> handle the G.729 to TDM codecing.

Yep, you would have to place the G.729 codecs on each of the endpoints
to cover the amount of calls you are trying to pass. This may be a
better solution for you as you can deploy a new machine per T1/E1 and
fill it out with the new license as it is deployed. Digium has already
commented about how painful it is to move or grow licenses afterwards. 
-- 
Steven Critchfield  <critch at basesys.com>