Coexisting with Previous Versions

Understanding Coexistence with Previous Versions of Exchange

Coexistence is a state in which various versions of Exchange are installed and running in the same organization. When you run your Exchange organization in mixed mode, coexistence is possible. Each version of Exchange can detect the other and share data with Active Directory. Exchange 2000 uses Active Directory and previous versions of Exchange use the Exchange directory. You can set up coexistence in organizations that have multiple divisions with different management structures and different implementation schedules.

Implementing Exchange 2000 requires time and planning. Coexistence is a viable solution for organizations wanting to implement the functionality Exchange 2000 immediately, before migration is complete.

Active Directory Connector and Coexistence with Previous Versions

Exchange 2000 is the first release of Exchange that relies completely on the directory provided by the operating system. Earlier versions of Exchange were integrated with the Windows NT security model, but rich directory information was contained in a separate database (Dir.edb). Because of its new architecture, for Exchange 2000 to fully coexist with earlier versions of Exchange, replication between Active Directory and the legacy Exchange 5.5 directory must take place. Replication is coordinated by Active Directory Connector (ADC).

For more information about coexistence and upgrading, see Microsoft Exchange 2000 Server Planning and Installation.

This section includes the following topics:

Related Topics

Managing Active Directory Connector