[asterisk-users] Asterisk 1.2.24 simultaneous call limits.

[Gordon Henderson]

On Thu, 20 Sep 2007, Wai Wu wrote:

>
> Hi everyone,
>
> I am running into wall today with simultaneous call limits. I have two
> Asterisk machines (fast 3GHz C2D with 2GB of ram). I tried to create a
> lot of sip calls from one machine to the other by issuing AMI Originate
> commands to one machine. The machine that makes calls plays a message
> (demo-intruct) upon the other machine answer. The machine receives the
> calls just waits for 40 seconds then hangs up. Throught the manager
> connection, I was creating 10 calls per-second. I also have sip phone
> registered with the calling machine. At around 150 to 200 calls. When I
> call the machine that's making all the calls, most of the calls couldn't
> go through. For the ones that went through, most of them will drop off
> within seconds of the call. But here is catch. When I run 'top', the cpu
> is idling 97%. My question is. Is there a limit on the number of
> simultaneous calls Asterisk can handle? I know I have very fast systems.
> Shouldn't they be able to handle that many calls? What is your take?

200 calls using g711 needs 16Mb/sec of network bandwidth - each way. (200 
* 80Kbs) This is well within the limits of a 100Mb network interface.

However it also needs 50 packets per second of 160 bytes + IP overhead 
each way, per call, so thats 20,000 packets/second, and that might well be 
the bottleneck for your system, not just in the hardware issues required 
to shovel that many packets over the various buses, but the Linux overhead 
of schedulling each of the 200 threads to take/send that data in 
real-time.

You might want to run iperf on each machine with nothing else going and 
see just how many UDP packets of 160 bytes you can push between the 
machines before packet loss starts.

Gordon