Mesh Topology

Mesh Topology
In a mesh topology (as shown in Figure 1.8), a path exists from each station to every other station in the network, resulting in the most physical connections per node of any topology. While
not usually seen in LANs, a variation on this type of topology—the hybrid mesh—is used on the Internet and other WANs in a limited fashion. Hybrid mesh topology networks can have multiple
connections between some locations, but this is done only for redundancy. In addition, it’s called a hybrid because other types of toplogies might be mixed in as well. Also, it is not a full
mesh because there is not a connection between each and every node, just a few for backup purposes. Notice in Figure 1.8 how complex the network becomes with four connections.

Example:

A typical mesh topology

As you can see in Figure 1.8, a mesh topology can become quite complex as wiring and connections increase exponentially. For every n stations, you will have n(n–1)/2 connections. For example, in a network of 4 computers, you will have 4(4–1)/2 connections, or 6 connections. If your network grows to only 10 computers, you will have 45 connections to manage! Given this impossible overhead, only small systems can be connected this way. The  ayoff for all this work is a more fail-safe, or fault-tolerant, network, at least as far as cabling is concerned. 

      Today, the mesh topology is rarely used, and then only in a WAN environment and only because the mesh topology is fault tolerant. Computers or network devices can switch between

these multiple, redundant connections if the need arises. On the con side, the mesh topology is expensive and, as you have seen, quickly becomes too complex. Using what is known as a partial mesh is a workable compromise between the need for fault tolerance and the cost of a full mesh topology. With a partial mesh, the same technology can be used between all devices, but not all devices are interconnected. Strategy becomes the name of the game when deciding which devices to interconnect.