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The datalink layer and the Local Area Networks

13 January, 2015 - 13:02

The datalink layer is the lowest layer of the reference model that we discuss in detail. As mentioned previously, there are two types of datalink layers. The first datalink layers that appeared are the ones that are used on pointto-point links between devices that are directly connected by a physical link. We will briefly discuss one of these datalink layers in this chapter. The second type of datalink layers are the ones used in Local Area Networks (LANs). The main difference between the point-to-point and the LAN datalink layers is that the latter need to regulate the access to the Local Area Network which is usually a shared medium.

This chapter is organised as follows. We first discuss the principles of the datalink layer as well as the services that it uses from the physical layer. We then describe in more detail several Medium Access Control algorithms that are used in Local Area Networks to regulate the access to the shared medium. Finally we discuss in detail important datalink layer technologies with an emphasis on Ethernet and WiFi networks.