[Asterisk-Users] asterisk load balance

[Aaron Daniel]

On Fri, 16 Jun 2006, Douglas Garstang wrote:
> Unless you can guarantee that the system that is currently processing a call will be the system that handles a transfer request from a phone, are the same, then transfers will not work.
Incorrect.  Transfers work fine between multiple asterisk boxes.

> Round robin DNS won't work at all. Every time you send out a SIP message, your going to be sending it to a different Asterisk box. For example, your initial INVITE will go to asterisk server 1. Asterisk server 1 will then send back a message requesting authorisation. Your phone does another lookup, and gets Asterisk server 2 this time. The phone sends the new INVITE with the auth info to Asterisk server 2. Asterisk server 2 will probably be ok with this, but when it sends a TRYING back to the phone, depending on the phone you are using, everything will fall in a heap on the floor. I know polycoms do. They get this TRYING from an asterisk server they didn't send and they go 'huh?'.
This is entirely phone dependant, and usually the phones that "fall in a 
heap" (like the phrase much?) also handle secondary server configurations 
MUCH better than the phones that don't.  Polycoms and sipura's handle SRV 
and backup server settings better than cisco's, but cisco's won't jump 
from server to server.

> I'm sure most other stuff will fail too. The Asterisk boxes share no state information.
It's all in how you program the dial plan.  The main thing that doesn't 
share state information that may cause problems is hinting.  Everything 
else is programmable somewhere in the system :)

> 	-----Original Message-----
> 	From: unplug [mailto:maillisting at gmail.com]
> 	Sent: Fri 6/16/2006 9:41 PM
> 	To: Asterisk Users Mailing List - Non-Commercial Discussion
> 	Cc:
> 	Subject: [Asterisk-Users] asterisk load balance
>
>
>
> 	Hi,
> 	  I am designing a asterisk load balancing model as follow.  There are
> 	3 asterisks connected to a single DB and a single server storing all
> 	the configuration file and voicemail.  Round Robin DNS will distribute
> 	the request to asterisks.
>
> 	DNS round robin ---+ asterisk1--------------------------+ DB and file server
> 	                             +---asterisk2-----------------------+
> 	                             +---asterisk3-----------------------+
Your design would work just fine as long as you have your dialplan is
configured right.  Keep in mind though that if asterisk1 dies, you just 
lost your db.

> 	Does anyone has load balancing experience implemented in asterisk that
> 	can share?  Does my design work?  Does any conflict will happen in my
> 	design?  Any comment?
> 	Thanks!
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-- 
Aaron Daniel
Computer Systems Technician
Sam Houston State University
amdtech at shsu.edu
(936) 294-4198