ABSTRACT

This entry describes the roles and functions of data transmission protocols used in today’s computer networks. An overview of computer network design models, namely, the Open System Interconnection (OSI) reference model and the transmission control protocol/Internet protocol (TCP/IP) model are provided, followed by the descriptions of some physical layer technologies including modem and asymmetric digital subscriber line (ADSL), and some commonly used data transmission protocols including Ethernet, Wireless Fidelity (WiFi), high-level data link control (HDLC) protocol, point-to-point protocol (PPP), IP, TCP, hypertext transfer protocol (HTTP), and simple mail transfer protocol (SMTP).