C H A P TER
The Internet protocols are the world’s most popular open-system (nonproprietary) protocol suite because they can be used to communicate across any set of interconnected networks and are equally well suited for LAN and WAN communications. The Internet protocols consist of a suite of communication protocols, of which the two best known are the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The Internet protocol suite not only includes lower-layer protocols (such as TCP and IP), but it also speciﬁes common applications such as electronic mail, terminal emulation, and ﬁle transfer. This chapter provides a broad introduction to speciﬁcations that comprise the Internet protocols. Discussions include IP addressing and key upper-layer protocols used in the Internet. Speciﬁc routing protocols are addressed individually in Part 6, Routing Protocols. Internet protocols were ﬁrst developed in the mid-1970s, when the Defense Advanced Research Projects Agency (DARPA) became interested in establishing a packet-switched network that would facilitate communication between dissimilar computer systems at research institutions. With the goal of heterogeneous connectivity in mind, DARPA funded research by Stanford University and Bolt, Beranek, and Newman (BBN). The result of this development effort was the Internet protocol suite, completed in the late 1970s. TCP/IP later was included with Berkeley Software Distribution (BSD) UNIX and has since become the foundation on which the Internet and the World Wide Web (WWW) are based. Documentation of the Internet protocols (including new or revised protocols) and policies are speciﬁed in technical reports called Request For Comments (RFCs), which are published and then reviewed and analyzed by the Internet community. Protocol reﬁnements are published in the new RFCs. To illustrate the scope of the Internet protocols, Figure 30-1 maps many of the protocols of the...