The protocols operating at the network layer of the Open Systems Interconnection (OSI) reference model are responsible for the end-to-end transmission of data across an internetwork. This is in contrast to data-link layer protocols, which are concerned only with transmitting packets to other systems on the local area network (LAN). This chapter examines the three most commonly used network layer protocols: Internet Protocol (IP) from the Transmission Control Protocol/Internet Protocol (TCP/IP) suite; Novell NetWare's Internetwork Packet Exchange (IPX); and Microsoft Windows' NetBIOS Enhanced User Interface (NetBEUI).
This chapter requires a basic understanding of the OSI reference model, as described in Chapter 1, "Networking Basics," as well as familiarity with the data-link layer protocols discussed in Chapter 5, "Data-Link Layer Protocols."