[Asterisk-Dev] Henning G. Schulzrinne quote on IAX2 from von magazine

[Brian West]

On Aug 13, 2005, at 1:45 PM, John Todd wrote:

> I hereby kill this thread and take it to the -users list.


Actually this should be on -dev because IAX2 does have scalability  
issues.  It will not and CAN NOT scale to large scales.  This is due  
to the single thread that handles all traffic in and out of the  
single UDP port.  As you start to load the box with calls the call  
quality starts to degrade and the delay shoots thru the roof.  You  
have one queue for receive and one for transmit that is serviced by  
the same thread.  Now if you pile on 30 calls with say a 300ms of  
latency it starts to sound like crap while running sip in the same  
situation sounds perfect.  IAX2 has its place but not in a large  
scale deployment at this time unless we can solve the issue with the  
bottle neck in the tx/rx queues.  I think we have talked about  
splitting the tx and rx queues into two threads that only gains a  
little bit of speed.  The next step would be to move this operation  
into the kernel since it does this and does it well already.  Then  
again on the other hand if you had an option to use a dedicated udp  
port per call that would also cause the issue to go away.  We could  
add something to punch thru nat and cause it to work just like it  
does now without much if any thought on the users side.

/b


  
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