Within MSMQ, a connected network (CN) is a collection of computers in which any two computers can communicate directly. The computers within a CN must support the same protocol and must be able to establish a session. A computer can belong to multiple CNs, and CNs can span sites. However, all computers in a physical local area network (all computers monitoring the same broadcasts) that use the same protocol (IP or IPX) must belong to the same CN.
When you define a CN, you are simply defining a label. When you install an MSMQ server, you associate each network address on the computer with the appropriate CNs. These CNs form logical groupings of computers that can communicate directly. MSMQ dependent clients use their supporting server CNs, and MSMQ independent clients automatically determine their CNs.
Tip When you define CNs for your enterprise, use meaningful labels so that administrators can easily choose a CN from a list when overriding the default CN settings. For more information, see "Naming Conventions" in Chapter 6, "Deploying MSMQ."
Figure 1.1
In most cases, the CN layout in an enterprise mirrors the protocol use. For example, in Figure 1.1, half the client computers run IP, the other half run IPX, and the servers run both IP and IPX. The MSMQ clients running IP belong to an IP CN and the MSMQ clients running IPX belong to the IPX CN. The servers belong to both CNs. However, CNs are not always defined to mirror protocol use. For example, you need two CNs when you have two separate IPX networks (subnets) on the same local area network.
Figure 1.2 shows an enterprise with two sites. The enterprise has two CNs, with one of the CNs spanning both sites. The servers belong to both the IP CN and the IPX CN to support the routing of MSMQ messages between CNs.
Figure 1.2
In this example, at least one of the two servers in the rightmost site must belong to both CNs in order for computers in the IPX CN to communicate with computers in the IP CN.