Intra-site routing is the process of routing messages within a site. MSMQ measures intra-site routing in hops, which is the number of MSMQ servers (PEC, PSCs, BSCs, or MSMQ routing servers) a message must pass through before reaching its destination. MSMQ always chooses the shortest available path when routing a message (unless routing restrictions have been applied by an administrator).
Figure 1.5
In Figure 1.5, any message sent from a computer in the IP CN to a computer in the IPX CN must make two hops: one hop to get to one of the MSMQ servers (assuming they both connect to both CNs) and one hop to get to the target computer. Because each hop is within a site, the cost of each hop is minimal.
The MSMQ intra-site routing system ensures that messages sent between two computers are delivered even if the two computers are never online at the same time.
For information on configuring intra-site and inter-site routing restrictions, see "Session Concentration" later in this chapter.