4 - Fast and gigabit Ethernet systems

Abstract

This chapter discusses basic methods for achieving fast, gigabit Ethernet systems. Theoretically, there are several ways to increase speed on a network. The easiest, is to increase the bandwidth and allow faster changes of the data signal. This requires a high bandwidth medium and generates a considerable amount of high frequency electrical noise on copper cables, which is difficult to suppress. The second approach is to move away from the serial transmission of data on one circuit to a parallel method of transmitting over multiple circuits at each instant. A third approach is to use data compression techniques to enable more than one bit to be transferred for each electrical transition. This chapter lists the basic methods used to achieve high transmission speeds on UTP Cables. It describes the operation of the 100Base-TX system, and lists the different physical media options for 100Base-T systems. The basic differences between a Class I and Class II repeater are explained and the packet bursting technique used by gigabit Ethernet is discussed. The chapter also lists the different media options used by gigabit Ethernet.