We have two main AD sites. in site2 we have two exchange 2007 servers running all the roles. users in site 1 have mailboxes in site 2 and access mail using outlook 2007. as we are expanding we want to do the following.
1. site 1 will be the only internet facing site
2. site 1 we will install two exchange servers configured as cas/mbx. max servers will be in a DAG.
3. since site two will host a large number of users will have two cas and two mbx servers.
4. we are planning to have a antivirus/antispam solution in site1.
5. cas in site1 and site 2 will be load balanced. i.e we will have two VIP'one for CAS in site 1 and second for CAS in site 2 (HW LOad balancer
6. we want clients in their respective sites to connect to their local CAS servers and clients in remote sites with no exchange servers connect to CAS in site1
keeping in view that we will be doing two things
1. migrate from 2007 to 2013
2. deploy additional servers in a site
what will be the best way to go forward.
we also have small remote sites with physical connectivity to site1 with no DC or exchange. only clients with outlook..