Business Data Communications and Networking

Chapter 4. DATA LINK LAYER

THE DATA link layer (also called layer 2) is responsible for moving a message from one computer or network device to the next computer or network device in the overall path from sender or receiver. It controls the way messages are sent on the physical media. Both the sender and receiver have to agree on the rules or protocols that govern how they will communicate with each other. A data link protocol determines who can transmit at what time, where a message begins and ends, and how a receiver recognizes and corrects a transmission error. In this chapter, we discuss these processes, as well as several important sources of errors.

OBJECTIVES ▾

• Understand the role of the data link layer

• Become familiar with two basic approaches to controlling access to the media

• Become familiar with common sources of error and their prevention

• Understand three common error detection and correction methods

• Become familiar with several commonly used data link protocols

CHAPTER OUTLINE ▾

INTRODUCTION

MEDIA ACCESS CONTROL

• Controlled Access

• Contention

• Relative Performance

ERROR CONTROL

• Sources of Errors

• Error Prevention

• Error Detection

• Error Correction via Retransmission

• Forward Error Correction

• Error Control in Practice

DATA LINK PROTOCOLS

• Asynchronous Transmission

• Synchronous Transmission

TRANSMISSION EFFICIENCY

IMPLICATIONS FOR MANAGEMENT

SUMMARY

INTRODUCTION

In Chapter 1, we introduced the concept of ...