Transitioning Client Access to Exchange Server 2010

Article complet sur la transition du CAS :
Source : http://blogs.technet.com/b/exchange/archive/2009/11/20/3408856.aspx

By now most of you have heard about the release of Exchange 2010. Those of you that are upgrading from Exchange 2003, Exchange 2007 or a mixture of the two, are probably curious about the client access upgrade strategy. To satisfy your curiosity, we are releasing a series of blog articles on the subject. The first in this series provides a summary of the steps that are required to introduce Exchange 2010 within your environment from a client access perspective. More detailed information about the upgrade process is discussed in TechNet and within the Deployment Assistant. The second and third parts in this series will discuss the end user experience for OWA and ActiveSync, respectively. Look for those in upcoming weeks.

Many of you have been asking how you can transition your existing Exchange environment to Exchange 2010 from a client access perspective. For most of you, this will also mean coexisting with legacy Exchange and Exchange 2010 for a period of time. This post will hopefully answer these questions by breaking down your transition into two scenarios:

1. Transitioning an Exchange 2003 environment to Exchange 2010.
2. Transitioning an Exchange 2007 (that may or may not contain Exchange 2003 mailbox servers) environment to Exchange 2010.

The underlying goal here is to move your primary namespace, mail.contoso.com and autodiscover.contoso.com, over to Exchange 2010 and introduce a new namespace for legacy access, legacy.contoso.com and associate it with your legacy Exchange client access infrastructure. Users will continue to use mail.contoso.com as their access point into the organization for messaging services. While Exchange 2003/2007 end users will see the legacy.contoso.com namespace in their browser address bar, ActiveSync settings, and Test Auto-Configuration output within Outlook, they only need to use the mail.contoso.com namespace as their primary entry point into the organization; in addition, IT should continue directing customers to utilize the mail.contoso.com namespace for all external connectivity mechanisms