Using *RT for HA purposes was: [Asterisk-Users] Realtime MultipleAsterisk boxes, iaxusers

[Alistair Cunningham]

Peter Bowyer wrote:
> I was thinking along the same lines, but for a dynamic setup it should
> be possible to have SER/OpenSER load balance REGISTER requests
> according to some strategy/metrics, and then forward INVITEs and other
> call-related traffic to the 'right' back-end server.
> 
> Probably lots of reasons why this is too complicated, though....

One being that it must be the device that NAT phones register with that 
delivers calls to them. Otherwise, the NAT device sees a packet coming 
from an unknown IP address and drops it (for common types of NAT such as 
  restricted cone). Since SER needs to deliver calls, it really needs to 
be SER that accepts REGISTERs and holds the registration information. 
The Asterisks then send calls from phones to the SER heartbeat address 
for delivery.

This is what we do in our ITSP in a box product. It gives us full 
redundancy and failover with the registration capacity of SER and the 
features of Asterisk.

For very large systems, it's possible to have SER redirect (with load 
balancing) REGISTERs to a set of SERs so that NAT devices know about the 
machines their phones are registered on, but this takes great care to 
get right in all cases.

Alistair Cunningham,
Integrics Ltd,
+44 (0)7870 699 479
http://integrics.com/