Understanding Routing Group Masters

When you create a routing group, the first server in that routing group is assigned the role of routing group master. The routing group master keeps track of the link state information and propagates it to the other servers in the routing group, and other servers communicate back any changes in link state. For example, if a member server tries to contact another server over a connector, and this link is unavailable, the member server immediately notifies the routing group master. Likewise, when a non-master receives new link state information, it immediately transfers the link state information to the master, so that other servers can receive the information about the routing change.

In a routing group, the routing group master and the other Exchange servers communicate link state information over TCP/IP port 691 using SMTP. However, communication of link state information between routing groups is different. If the routing group master is not a bridgehead server for the routing group, the routing group master sends the link state information to the group's bridgehead server over TCP/IP port 691. The bridgehead server then forwards this information (over TCP/IP port 25 using SMTP) to the bridgehead servers of other routing groups.

If you do not want the first server installed in the routing group to be the routing group master (the default setting), you can change the routing group master to another server. For detailed information about changing the routing group master, see "How to Change Which Server Is the Routing Group Master" in the Exchange Server 2003 Transport and Routing Guide.