quote:

ORIGINAL: barry.anns

Hi,

I'm running an Exchange 2003 organisation with just over 20 servers, all in separate Administrative groups and child domains.

In my root domain, I have an Exchange 2003 server running as a front end OWA server. The rest of the Exchange 2003 servers in the org are all back end servers. We also have an Exchange 2003 bridgehead server in the root domain too for core SMTP mail delivery and bridging.

We keep all servers on the same patch level, as experience has taught us that this is the way OWA functions best, and this is a mission-critical app for my company.

We are now in the situation where we are planning an Exchange 2007 installation on one of the child domains.

The mailboxes on this Exchange 2007 will need to be accessed via the same front end Exchange 2003 server.

I have read this: http://www.microsoft.com/technet/technetmag/issues/2006/12/OWA/ and note the following:

"Backward Compatibility

The heart of Outlook Web Access in Exchange Server 2007 is the CAS, and the CAS model has been built up to provide the best possible interoperability with servers running earlier versions of Exchange. To ensure that this works, you should always deploy or upgrade your CAS servers before upgrading their associated mailbox servers.
An Exchange 2007 server with the CAS role can be used to connect to mailboxes on Exchange 2000 and Exchange 2003 servers. RPC over HTTP and Exchange ActiveSync® will both continue to work with a partial site upgrade. OWA and WebDAV will also work if you access them through the /exchange, /public, or /exchweb virtual directories. You can create custom OWA virtual directories for these earlier versions on Exchange Server 2007 as well."

Do I take it from this that I need to upgrade my Exchange 2003 front end OWA server to Exchange 2007 BEFORE I install a new Exchange 2007 back end server, and that this will guarantee compatibility of OWA throughout my Exchange organisation for all users?

Thanks for your help.

quote:

ORIGINAL: barry.anns

John,

Thanks for the input but can I clarify something first:

We have two Exchange 2003 servers in the first administrative group at the datacentre, one is used for OWA and the other for a bridgehead server. All other sites are linked to the datacentre in a hub and spoke topology using private links.

From what I can find so far, still doing some labs internally to test further, is that all I need to make sure I upgrade would be the OWA server to Exchange 2007. Then the install of the hub site as Exchange 2007 with the Mailbox and hub transport role but set it to communicate with the bridgehead server at the datacentre?

Thanks in advance!

Barry