Overview

In this chapter we discuss the second layer of the OSI model, namely, the data link layer. This layer handles the transfer of data between the ends of a physical link it is responsible for transferring data from the network layer on the source machine to the network layer on the destination machine. We discuss this layer from the perspective of the IEEE LAN architecture rather than the OSI model. As part of this perspective, we introduce the various IEEE LAN standards and the two general IEEE algorithms that serve as the basis for LAN protocols.

1. What is the IEEE?

   IEEE (pronounced "eye triple E") stands for the Institute of Electrical and Electronics Engineers, a professional society founded in 1963. IEEE members include engineers, scientists, and students. One of its many activities is to act as a coordinating body for computing and communication standards. Many international standards from the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) are based on IEEE networking standards. For additional information about these organizations, see http://www.ieee.org; http://www.iso.ch; and http://www.iec.ch.

2. What does IEEE have to do with local area networks?

   In the early days of local area network development, there were no standards for LANs. Chaos and instability were the order of the day. Proprietary vendor standards ruled, customers became customers-for-life, and companies got fat. The dearth of industry-wide standards effectively prevented customers from using "outside" products for fear of incompatibility. In February 1980, the IEEE assumed responsibility for setting LAN standards, primarily...