7 - Meet Joe's Packets

Abstract

This chapter begins by looking at what the end user (Joe) does, but only in terms of how it starts processes in motion. These processes may occur anywhere, but the interactions happen at several different levels. Starting with Joe's keystrokes (his interaction with the network-connected system), this chapter gives a look at how systems interact at the application, transport, internet, and network link layers. The protocols described here are far from the only ones Joe's packets use, or cause to be used by other nodes — nor are they the only important ones. The objective of this chapter is not to exhaustively demonstrate all internet protocols, but to give a sense of how those protocols work. In this chapter, a lightning tour of the TCP/IP protocol suite is taken, looking briefly at the ways in which data moves from one application to another. Many of the issues relating to the protocols have been omitted to avoid complicating matters; some of the subtleties of the protocols have been glossed over to avoid getting mired in specifics. However, for most people, this chapter should be more than sufficient to explain how the internet works and how internet mail, web browsing, and other applications work.