Hi, I'm planning a Exchange 2007 Solution for the company, there are 150 thousand users. As you know, in Exchange 2007, there are five distinctroles, for mailbox server, we can leverage Windows Cluster, for Client Access Server, we can leverage Windows NLB, but Edge and Hub Server, there is no a very strong / reliable HA solution, they only depend on DNS. Could give more HA info for Edge and Hub? By the way, besides of mailbox server and client access server, in a general Exchange 2007 deployment scenario, Shall I deploy every role (besides of UM)? If there are no Edge / Hub, Exchange 2007 can function? And, what if I deploy Edge role, Can I close existing Microsoft Antigen for SMTP? Or both of them (Edge and Antigen) can co-operate for better anti-spam and anti-virus? Thank you!

hi, You definitely need the Hub transport role.If you have multiple AD sites you need a hub (and cas i believe.....client access) role for every site that has mailbox servers.For HA for hub transportmultiple servers are recommended........as for the ratio of hubs to mailbox servers, I am not sure.......last I heard MS hadn't fully decided on recommendations for it. Edge servers are for your perimiter network to be used as a gateway for mail so they are not required unless you are going to use exchange as your smtp gateway. I also think you should still have AV aswell as anti-spam hope this helps

See http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help/d2efb6f9-f70a-4f96-9f8d-f7aad6ae83d7.mspxfor details on HA for each of the server roles. There is an HA configuration for all server roles. Each site containing a Mailbox server must also have at least oneClient Access and Hub Transport server. For Edge, you can run Microsoft Forefront for Exchange (formerly Antigen) directly on the server. If you buy the Enterprise CAL, Forefront is included. See http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help/a5333be9-94af-4721-8678-e0a2706ec98b.mspxand http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help/1e5b38ba-e6d8-4b6c-b5dd-93769391a04e.mspxfor more information. Hope this helps.

Scott, Struggling with same question as person that started this thread. I read the HA article, am clear on most everything (using CCR for MS, NLB for CAS)except the Hub Transport role. Specifically: How can I ensure redundancy for inbound SMTP traffic (in a case where I don't have an Edge transport - have external spam and virus filtering, and am still using ISA 2004)... Should/Could I use NLB for HUB servers? If not, then what are the options / suggested methods ? Thanks, Andre.

No need for NLB for Hub Transport servers, as resiliency is built into those servers. You can use NLB for CAS servers. If you have multiple Hub Transport servers that will receive incoming Internet mail you can use DNS RR to load level across them. But for Hub, the key is really having multiple servers.