Connecting Routing Groups
When you create a routing group, you designate a group of servers that can communicate directly with one another. As discussed earlier, for servers in different routing groups to communicate with each other, you must connect the routing groups.
You can connect routing groups with an SMTP connector or an X.400 connector. However, using these types of connectors is typically not recommended. The preferred connection method is a routing group connector because this connector is designed and intended specifically for connecting routing groups.
Routing group connectors are one-way routes for outgoing messages, which means messages travel outbound to the connected routing group. For two routing groups to communicate, a routing group connector must exist in each routing group to send messages outbound to the other routing group. When you create a connector to a routing group, Exchange displays a message that prompts you with the question of whether you want to create a routing group connector in the remote routing group so that you can send messages from the remote routing group to the routing group where you are creating the first connector.
Before you create and configure a routing group connector, think about the following questions:
**To which routing group does this connector deliver messages? **This information is critical. Identifying the routing group to which the connector delivers messages establishes the relationship between the sending and receiving routing groups and the rest of your topology. You must know how the sending and receiving routing groups fit into your topology to intelligently assign a cost for the associated connector.
What cost should this connector have? Cost is the variable Exchange uses to determine the most efficient messaging route. Exchange considers the lowest cost route the most efficient. Exchange uses a more expensive route only if a server or connector is unavailable on the route with the lowest cost. Assign the lowest costs to the routes with the highest available network bandwidth.
Which servers in the routing group can act as bridgehead servers? Only designated bridgehead servers can send messages across the connector to the connected routing group. The default and preferred setting is to have any of the servers in the local routing group send mail using this connector. Use this default option when all servers in the routing group can connect directly over the network to the remote bridgehead server. Connecting directly to the remote bridgehead servers provides more efficient message flow.
However, you may have better direct network connectivity between specific servers in the local routing group and the designated remote bridgehead server. For example, Server A has a direct connection of 56 kilobits per second (Kbps) to a remote bridgehead server, while Server B and Server C each have a direct connection of 10 megabits per second (Mbps) to the same remote bridgehead server. In this case, you would want to specify the servers that have the better direct network connectivity (that is, Server B and Server C) as the bridgehead servers, and you would add those specific servers to a list of permitted bridgehead servers.
Should users access public folders that are not available locally using this connector? By default, public folder referrals are enabled across connectors connecting routing groups. However, network traffic increases when users access a public folder in a remote routing group. If your routing groups are connected by slow network connectivity or if your network may not be able to handle the additional traffic, disable public folder referrals. For more information about public folder referrals, see "Understanding Public Folder Referrals."
**What are the remote bridgehead servers to which this connector can send messages? **The remote bridgehead servers are the servers in the connected routing group that receive all messages destined for this routing group. The remote bridgehead servers also send link state information to the bridgehead servers for the connector.
After considering these questions, you answer the first four by setting the configurations options on the General tab in the Routing Group Connector Properties dialog box. You can answer the last question by specifying remote bridgehead servers on the Remote Bridgehead tab.
For detailed instructions about working with connectors, see the following topics: