Chapter Summary

A routing group is a collection of Exchange 2000 servers that typically share a permanent, reliable, high-bandwidth network connection. In a particular routing group, all servers communicate directly with each other using SMTP. If your entire network consists of LAN-like connections, you will find the deployment of a single routing group sufficient and advantageous. If you need to control and optimize the flow of messages, on the other hand, you should implement multiple routing groups and connect them using an RGC. It is possible to place all servers in one administrative group for global administration, but they must be in multiple routing groups.

To link separate routing groups of an organization together, you can use RGCs, SMTP Connectors, or X.400 Connectors. Only these connectors support native Exchange message formats, public folder referrals, and link state information. The RGC is the most powerful and easiest to configure, followed by the SMTP Connector. The X.400 Connector configuration, on the other hand, is a complex challenge. It is advisable to rely on X.400 Connectors only for the purpose of building messaging bridges to foreign X.400 systems.

Exchange 2000 Server features a powerful routing engine that is able to determine the most efficient message routes based on link state information. Within each routing group, a master maintains an LST that holds information about the current conditions within the network. The LST is propagated to all servers in the routing group via direct TCP/IP connections. Between routing groups, link state information is transferred by means of RGCs. Message loops and ping-pong effects can be prevented efficiently using link states.