Chapter 5 - Data Link Layer Concepts and IEEE Standards

Abstract

The purpose of this chapter is to discuss the second layer of the Open Systems Interconnect (OSI) model—namely, the data link layer. This layer handles the transfer of data between the ends of a physical link that is responsible for transferring data from the network layer on the source machine to the network layer on the destination machine. The data link layer is the “glue” between the wire and the software on a node. Without it, the particular network connection will not operate at all. It creates the network environment for the wire and dictates data formats, timing, bit sequencing, and many other activities for each particular type of network. The chapter provides an overview of the data link layer and provides information about IEEE, which developed data link layer protocols that serve as the basis for various local area network (LAN) technologies such as Ethernet and token ring. The chapter also examines the data link layer from IEEE's perspective. The concepts of data prioritization and quality of service (QoS) that are integral to the delivery of time-sensitive data such as real-time voice and video traffic are also discussed. Satellite communications are based on radio frequency (RF) transmissions. Satellite communication systems consist of ground-based (also called terrestrial) stations made up of a parabolic antenna (transmitter/receiver) and orbiting transponders. Probably the biggest advantage of satellite communication is they can reach geographically remote areas.