Chapter 3: Multipoint-to-multipoint
Posted by Mungo under Chapter 3 on February 24th, 2007.The third type of network layout is multipoint-to-multipoint, which is also referred to as an ad-hoc or mesh network. In a multipoint-to-multipoint network, there is no central authority. Every node on the network carries the traffic of every other as needed, and all nodes communicate with each other directly.
The benefit of this network layout is that even if none of the nodes are in range of a central access point, they can still communicate with each other. Good mesh network implementations are self-healing, in that they automatically detect routing problems and fix them as needed. Extending a mesh network is as simple as adding more nodes. If one of the nodes in the “cloud” happens to be an Internet gateway, then that connection can be shared among all of the clients.
Two big disadvantages to this topology are increased complexity and lower performance. Security in such a network is also a concern, since every participant potentially carries the traffic of every other. Multipoint-to-multipoint networks tend to be complicated to troubleshoot, due to the large number of changing variables as nodes move around. Multipoint-to-multipoint clouds typically do not have the same capacity as point-to-point or point-to-multipoint networks, due to the additional overhead of managing the network routing and increased contention in the radio spectrum.
Nevertheless, mesh networks are useful in many circumstances. We will see an example of how to build a multipoint-to-multipoint mesh network using a routing protocol called OLSR at the end of this chapter.
