[asterisk-users] Large Asterisk installarions (~10, 000 extensions), preferably at universities

[Terry Wilson]

> Yehavi Bourvine wrote:
>
>> OK, but I still did not get a reply to my original question: Why  
>> using
>> SIP registrar in front of Asterisk and not simply use bare Astersik?
>> can't it handle the load? (remember - in my case it doesn't handle  
>> the
>> RTP, only signalling). Can't it handle so much registrations? (I am
>> using realtime DB, it is has any relevance).
>
> My experience has shown that using a dedicated registrar for large
> installs is more effective;  it doesn't tie up resources on the  
> Asterisk
> box with all those registration refreshes, for one.  A product built  
> to
> be a high-throughput standalone registrar will handle the concurrency
> requirements and perform better.

I've looked at doing various things to chan_sip to improve signaling  
performance (hash tables for call lookups, etc.)  I gave up when I  
realized that the overhead of handling the RTP was so far above the  
overhead of processing SIP signaling that it didn't really matter  
much.  The only reason I have ever had to use a SIP registrar (OpenSER  
in my case) was if I needed to load balance calls across multiple  
asterisk servers.  If most of the phones are not separated by a NAT  
from Asterisk (as would be the case in something like a University  
network), the registration timeout could be set to a relatively high  
value w/o causing any problems which would cut down on some of the SIP  
traffic from registrations.

In fact, I just ran some tests using SIPp and w/o any audio, using  
realtime w/ 10k accounts I can register 100/second while doing 10  
calls/second.  If you are looking just at registrations every 15  
minutes or so, that is 90k devices that could register to asterisk.   
This was using 1.6.0.1 on my little HP amd64 development box--not  
anything near the kind of machine that you would probably install in a  
large installation.  Asterisk just gets faster and faster.  Some of  
the "it isn't good at x" stuff comes from experiences with older  
releases.

If you are lucky enough to have a situation where you can re-invite  
media and keep it off of the asterisk box, it can handle huge loads.

Terry