Understanding Site Replication Service

Exchange 2000 includes Site Replication Service (SRS), which emulates an Exchange 5.5 directory service. SRS is installed during setup and is used to communicate to servers running Exchange 5.5 in the same site or other sites.

When you install SRS on an Exchange 2000 server that acts as a directory replication bridgehead for an Exchange site, the server configures the Configuration Connection Agreement. This ensures that, as SRS receives directory replication messages from other sites, the replicated directory information synchronizes from the Exchange 2000 server to Active Directory over the Configuration Connection Agreements for ADC.

When Exchange 2000 functions as the directory replication bridgehead server in an Exchange 5.5 site, SRS manages the directory replication traffic in its configured sites. SRS builds directory replication messages and sends them to the destination site using the messaging connector configured for the destination site. SRS also accepts replication messages from other sites for which it is configured.

The directory service of previous versions of Exchange uses Remote Procedure Calls (RPCs) for intra-site communication. When Exchange 2000 is installed in an Exchange 5.5 site, SRS uses RPCs to communicate with previous versions of Exchange.

SRS is similar to the Exchange 5.5 directory service, except that the Named Service Provider Interface (NSPI) is disabled to prevent Outlook clients from connecting with and using the Exchange 5.5 directory for resolution. Also, because ADC supports only LDAP, SRS must run an instance of this protocol. To prevent port conflicts when Exchange 2000 is running on a domain controller, the LDAP interface for SRS monitors port 379.

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