[Asterisk-Users] Re: load balancing 20 asterisk servers

[Rich Adamson]

> DNS based load ballancing has it's place, as dose using an
> application level switch.  
> 
> Say an earthquake takes out your California data center.
> Shortly the DNS servers will notice and pull that center's
> record.  However do to caches and all this is not fast
> and users will notice.
> 
> What the switch does is route at the protocol level between
> local machines.  You can take a machine off line and no one
> will notice.  Works great until the big quake a backhoe
> takes out a fiber cable ro there is a fire flood or who
> knows what.

You have fiber-seeking-backhoes in your area? Wow!

> protocol level switches have to "know" about the protocol.
> You can buy them that work with HTTP, HTTPS and the common ones
> but I wonder aboit SIP?  Getting the RPT to the right * server
> would be hard beetrer to have a proxy tell the user which *
> server to go to and nothave to route RTP.

Handling sip-rtp via a load balancer is roughly equivalent to
handling ftp (ports 20 & 21, passive, etc). The load balancer
really needs to inspect sip packet content and follow the rtp
port negotiation process. I'm not aware of any balancers that
can do that today.