Coexisting with Previous Versions

Understanding Message Routing Issues

ADC and SRS provide replication not only for user objects in the site naming context, but also for the configuration naming context. This means that an Exchange 2000 server reads the connected site and address space information from servers running earlier versions of Exchange and places that data in its link state table, which replaces the Gateway Address Resolution Table (GWART).

This allows Exchange 2000 to use any existing connectors, whether they are provided by Exchange or not; for example, Exchange 2000 does not include Professional Office System (PROFS) and SNA Distribution System (SNADS) connectors. If you need connectivity to these systems, you must install the connectors on an Exchange 5.5 server; however, Exchange 2000 can send and receive messages through this route. Similarly, any routes in Exchange 2000 are replicated by ADC and SRS to servers running earlier versions of Exchange, so that those servers can also use connectors specific to Exchange 2000.

Note   Previous versions of Exchange cannot be installed in Exchange 2000 routing groups; however, you may have legacy Exchange connectors that you want to continue using with Exchange 2000. In this case, you need to create a separate Exchange site, which contains these servers running earlier versions of Exchange, and configure routing such that messages destined for those legacy connectors are routed to the Exchange site you created.

Setting Up Coexistence Between an Exchange Site and Routing Groups

The following scenario explains how Exchange sites and routing groups can coexist:

A company has three Exchange sites: the North American site is running Exchange Server version 5.0, and the South American and European sites are running Exchange 5.5. Each site is controlled by a separate administrative organization with a separate budget. The European site is upgrading to Exchange 2000. After upgrading Europe to Exchange 2000, the Exchange 2000 routing group will coexist with North America and South America using the existing X.400 connectors.

In this scenario, Exchange 2000 routing groups are coexist with sites running earlier versions of Exchange. Messaging and directory replication connectivity must be maintained.

Messaging Connectivity

Exchange 2000 coexists with the Site connector, SMTP connector, and X.400 connector using TCP/IP. Any of these connectors can be used to deliver messages between Exchange 2000 routing groups and sites running earlier versions of Exchange. If the Site connector is used, the Exchange 2000 Routing Group connector is configured in the Exchange 2000 routing group. The Routing Group connector communicates with the pre-Exchange 2000 Site connector using the native RPCs.

Directory Connectivity

Because there is no Exchange directory in Exchange 2000, any replicated directory information from a site running earlier versions of Exchange must be replicated to Active Directory. SRS must be installed on an Exchange 2000 server in the routing group. This server should be configured as the directory replication bridgehead server for the destination site. This means that directory replication messages from the site running earlier versions of Exchange are sent to the Exchange 2000 server running on which SRSis installed. This computer should be configured as the server in the Configuration Connection Agreement for ADC. As this server receives replication messages from the Exchange site, SRS accepts the messages, and then ADC synchronizes the directory changes to Active Directory.

Related Topics

Understanding Coexistence with Previous Versions of Exchange Routing Groups and Message Routing