Understanding Connection Agreements in Exchange

This article describes Connection Agreements and their functions. This article also describes the different types of Connection Agreements that can be configured under an Active Directory Connector (ADC) in Exchange.

Connection Agreements act as a control mechanism for replicating folder and configuration information between an Exchange Server 5.5 computer and Active Directory. On the Exchange side, the Exchange bridgehead server must be running Exchange Server 5.5 Service Pack 3 (SP3) or later.

You can only create Connection Agreements that replicate folder information by using the ADC; however, there are three types of Connection Agreements that you can view by using the ADC:

• Recipient Connection Agreements replicate recipient directory objects between the Exchange Server directory and Active Directory. ADC displays the names of these Connection Agreements.
• Public folder Connection Agreements replicate public folder objects between the Exchange Server folder and Active Directory. ADC displays the names of these Connection Agreements. If you want to email Exchange Server 5.5 public folders from Exchange 2000 or Exchange Server 2003 mailboxes, you must create a public folder Connection Agreement for each Exchange Server 5.5 site in the organization.
• Configuration Connection Agreements replicate Exchange Server-specific configuration information between the Exchange Server 5.5 folder and Active Directory. These agreements help Exchange 2000 and Exchange Server 2003 coexist with earlier versions of Exchange Server and Windows NT. ADC displays these Connection Agreements and lists the bridgehead servers that they use.

How to Replicate Folder Information Between Exchange Server 5.5 and Active Directory

Recipient Connection Agreements replicate recipient directory objects between the Exchange Server 5.5 directory and Active Directory. Public folder Connection Agreements replicate public folder directory objects between the Exchange Server 5.5 directory and Active Directory.

Both recipient and public folder Connection Agreements are user-defined. However, ADC automatically enables many options for public folder Connection Agreements and does not allow you to change them. Public folder Connection Agreements differ from recipient Connection Agreements in the following ways:

• Public folder Connection Agreements always use two-way replication.
• Public folders are the only objects that you can replicate in a public folder Connection Agreement. In recipient Connection Agreements, you can select various objects.
• For public folder Connection Agreements, the ADC automatically selects the Windows organizational unit, the Exchange Server container, and the default destination containers for Windows and Exchange Server. You cannot change these containers.
• Public folder Connection Agreements are always primary Connection Agreements from Exchange Server. You cannot change this value.
• Public folder Connection Agreements always use objects' Exchange Server 5.5 distinguished names to create their location on the Windows 2000-based computer.
• Public folder Connection Agreements cannot be inter-organizational Connection Agreements.

Although you can install only one instance of ADC on a computer running Windows 2000 Server, you can establish multiple Connection Agreements. You can configure each Connection Agreement to perform unique replication tasks; for example, one Connection Agreement can continuously update Active Directory, while another Connection Agreement can update Windows contacts to the Exchange Server folder daily at 6:00 P.M.

Note To add Exchange mailboxes when you create new users in the Active Directory Users and Computers snap-in, you must configure a two-way Connection Agreement or a one-way Connection Agreement from Windows to Exchange. A one-way Connection Agreement from Exchange Server to Windows does not provide the option of adding a mailbox for the user because one already exists.

You can also establish a primary Connection Agreement. A primary Connection Agreement creates new objects, while all other Connection Agreements only replicate information to existing objects.

Automatically-Generated Configuration Connection Agreements

Configuration Connection Agreements (CA) are designed to replicate system-level objects between Exchange 5.5 and Active Directory. These system-level objects include connectors, routing, and information store settings. Configuration CAs are automatically generated when you install the first Exchange 2000 or Exchange 2003 computer in a pure Exchange 5.5 site. Configuration CAs are automatically configured to replicate between an Active Directory domain controller and the Exchange 5.5 directory. The Exchange 5.5 directory is provided by the Site Replication Service. The Exchange 5.5 directory resides on port 379 of the newly-installed Exchange 2000 or Exchange 2003 computer.

Note When a configuration CA is created, the replication schedule is set to Never until Microsoft Active Directory Knowledge Consistency (Knowledge Consistency Checker) runs in the site. Knowledge Consistency Checker is an automated background process. After each configuration CA is created, it is best to permit Knowledge Consistency Checker to change the replication schedule to Always.