Steps to upgrade the version of Exchange 2010

HI,

We need to upgrade new version of exchange 2010. We have single site scenrio where CAS+HUB+MBX on one server. CAS is behind the hardware load balancer and DAG is configured. we have also 2 servers where CAS+HUB+MBX role is installed but on these server DAG is not configured but CAS are the members of same same CAS array behind the hardware load balancer.

In this scenario what should be the steps to upgrade the new versions(patching/SP/update rollup) of exchange 2010

Thanks  

jitender