This reference has now been divided into two volumes to reflect the most recent changes in the field. Volume 1 provides a broad, conceptual introduction to the TCP/IP internetworking protocols and the connected TCP/IP Internet. It reviews network hardware, including wide area national backbones ARPANET and NSFNET, and local area technologies Ethernet and token rings. Addre This reference has now been divided into two volumes to reflect the most recent changes in the field. Volume 1 provides a broad, conceptual introduction to the TCP/IP internetworking protocols and the connected TCP/IP Internet. It reviews network hardware, including wide area national backbones ARPANET and NSFNET, and local area technologies Ethernet and token rings. Addresses binding (ARP) and the IP concepts of connectionless datagram delivery, error detection and control, multicasting, and routing are covered. In addition, Comer compares the ISO 7-layer reference model to the TCP/IP 5-layer model in his discussion of protocol layering.