Mesh Topology

Meshing generically describes how devices are connected together. There are two types of meshed topologies: partial and full. In a partially meshed environment, every device is not connected to every other device. In a fully meshed environment, every device is connected to every other device. Figure 1-3 shows examples of these two types of topologies.

Note that like the topologies in the preceding section, partial and full mesh can be seen from
both a physical view and a logical one. For example, in a physical bus topology, all the devices are fully meshed, since they are all connected to the same piece of wire—this is both a physical and logical fully meshed topology. This
is common in LAN topologies.

WANs, on the other hand, because of their cost, commonly use partially meshed topologies to reduce the cost of connected devices. For example, in the partially meshed network shown in the top part of Figure 1-3, the top, right, and bottom devices can all communicate via the device on the right-hand side. This communication introduces a delay in the transmission, but it reduces the cost, since not as many connections are needed.