Exchange CAS - internal load balance

First thing to know about your config is which version are you using (10.x or 11.x). For version 10, you can use template to deploy your environment. For version 11, you can use iApp to deploy Exchange with the latest iApp template for exchange (v1.2). Basically, on 11.x you will have two combined vs for http and https with an irule to switch between your pools and a smtp vs for internal users. On 10.x, my config has one vs for external smtp, one vs for internal smtp, one vs for rpc mapi, one for https and http redirect.