[Asterisk-Users] Re: How far is IAX to be a Standard

[Matt Riddell]

niels at wxn.nl wrote:
--SNIPSTA--
> Anyhow, the situation now, is that there is no DSP chip, that means ..
> Your main processor has to encode the channel in total (3 to 4 E1's
> absolute is the max possible with dual xeon 3 ghz I read somewhere in
> this case) 

This has a problem.  PC's are so cheap now that you'd be silly to have 
more than 4 E1s on one PC.  The idea is not to build one huge PC, but 
multiple small ones.  This helps no end when trying to add redundancy etc.

I.E. if you have say 5000 lines on one PC (to take it to the extreme) 
and that PC dies, you have just lost 5000 lines.   If you have 100 lines 
per sever and 50 servers, you only lose 100 lines if the PC dies, and 
you can probably reroute to other servers.

> Another method is to send the incoming IAX on asterisk out again with
> SIP to a gateway with hardware DSP's.. (like we do).. This needs less
> performance ofcourse because asterisk doesn't have to do codec encoding,
> but nevertheless will still have to transcode to get the signaling and
> RTP merged and submerged from/to this one IAX port to separate
> Signaling/RTP ports.. Our setup now is the second scenario.. And my
> first (rough) calculations are that a dual xeon 3.0 ghz can handle about
> 500 concurrent channels in this scenario...

As above.

> Ever wandered why there isn't any codec (DSP) hardware availiable for
> asterisk?? I think here is the answer, because it is very hard to make,
> Digium should then be able to design a totally new DSP chip design ..
> And that's much more difficult than to design an E1 board. 

No.  The reason that there is none is that Asterisk is designed to use 
cheap off the shelf PC hardware.

> Our case is that we have about 200 E1's of voip (h323 and sip) traffic
> and are still expanding. If we would have this all on IAX this would be
> unmanageable, we would need 50 linux boxes.

As above.

> Conclusion.. IAX Is a good performer behind NAT and perfect for small
> setups but to work in an enterprise, Much work has to be done.

I'd say some learning on high availability Linux/clustering etc is in order.

-- 
Cheers,

Matt Riddell
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