[Asterisk-Users] Hypothetical : Working across multiple servers??

[WipeOut]

Hypothetical question..

Lets say there is a situation where you are using the highest 
compression codecs for all extensions (I guess that would be G.729) and 
the load on a single server is overpowering the most powerful single 
processor(lets say SMP is not an option).. So two or more servers are 
required..

Or

The situation is that you need fault tolerance so want to have two 
Asterisk servers serving the same population of users and all users are 
able to authenticate to both servers (I guess you simply copy the same 
sip.conf to both servers for this) but you also want all other 
extensions to be availible to all users irrespective of which server 
they have connected to..

I guess in a way it would be like an Asterisk cluster of some sort..

What would the solution be? Has anyone got an install similar that they 
would like to share how it was done?

Later..