|  |  | Overview

All data sent out on a network is from a source and is going to a destination. After data is transmitted, the data link layer of the OSI model provides access to the networking media and physical transmission across the media, which enables the data to locate its intended destination on a network. In addition, the data link layer handles error notification, network topology, and flow control.

In this chapter, you will learn about LAN media and the IEEE model and you will learn how the data link layer provides reliable transit of data across a physical link by using the Media Access Control (MAC) addresses. In so doing, the data link layer is concerned with physical (as opposed to network, or logical) addressing, network topology, line discipline (how end systems will use the network link), error notification, ordered delivery of frames, and flow control. In addition, you will learn how the data link layer uses the MAC address to define a hardware or data link address in order for multiple stations to share the same medium and still uniquely identify each other.