8 - Application layer protocols

Abstract

This chapter focuses on application and operation of different application layer protocols and examines the process/application layer of the TCP/IP model. Protocols at this layer act as intermediaries between some user application (external to the TCP/IP communication stack) and the lower level protocols such as TCP or UDP. The file transfer requires a reliable transport mechanism, and therefore TCP connections are used. The file transfer protocol (FTP) process running on the host that makes the file transfer request is called the FTP client, while the FTP process running on the host that receives the request is called the FTP server. The trivial file transfer protocol (TFTP) is a less sophisticated version of FTP, and caters for situations where the complexity of FTP and the reliability of TCP is neither desired nor required. TELNET (telecommunications network) is a simple remote terminal protocol, included in the TCP/IP suite that enables virtual terminal capability across a network. This chapter explains the operation of different application layer protocols including FTP, TFTP, TELNET, RLOGIN, NFS, DNS, WINS, SNMP, SMTP, POPS, HTTP, BOOTP, and DHCP.