Overview

Before we can usefully discuss the operation of the Internet protocols, we must first have a basic understanding of how Local and Wide Area Networks operate. In addition, there are a number of different devices that are used to interconnect our networks and an idea of their operation, advantages and shortcomings is equally important. This chapter is not designed to be a definitive discussion of LAN and WAN technologies. Instead, as its title suggests, this is an overview. There are many books on this subject and where further information is required, the reader is urged to either consult such a book or refer directly to the relevant standards.

For LAN technologies, most commonly today we find Ethernet, Token Ring, and the Fibre Distributed Data Interface (FDDI) used. As for WAN technologies, many standards exist including RS-232C, RS-442/9, X.21, X.25, V.35, and ISDN. In this chapter we shall look at these LAN/WAN technologies and how the various internetworking devices and the Internet protocols are used with them. In Chapter 22, we also look at the transmission of the Internet protocols over serial WAN links and see how TCP/IP can be used in wide area networks.

3.1 Ethernet and IEEE 802.3

Possibly the most prevalent of all LAN access methods is Ethernet. Be warned though, many people that use 802.3 LANs will also refer to them, albeit wrongly, as being Ethernet. When used in this context, the terms Ethernet and 802.3 are generally used to refer to the types of cabling,...