Murder cluster questions

[Brenden Conte]

I have some questions, mainly around murder and versions. 

We're looking to expand to a Murder cluster, but are still running 2.2 
versions of the software.  Obviously, i would like to use the latest 
version for any new installs, so I was wondering - both in the context 
of building the cluster as well as future upgrades - if there is a 'all 
same version' requirement (i.e. all servers must be upgraded at the same 
time) or whether the protocol was standard enough that it didn't matter 
(Between frontend and backends?  Between backends (i.e. moving a 
mailbox)? Master vs frontend vs backend?) 

Naturally, this question doesn't involve using "new" features not 
present in the older versions.

Thanks in advance for your responses!

-- 
Brenden Conte
System Programmer, C&MT.CIO
Rensselaer Polytechnic Institute
(518)276-4264