Book Image

Understanding TCP/IP

By : CP Books a.s.
Book Image

Understanding TCP/IP

By: CP Books a.s.

Overview of this book

This book covers in detail the Open System Interconnection (OSI) reference model and the TCP/IP protocols that operate that different layers. Its coverage includes various application protocols. The authors explain in an easy-to-read style networking concepts and protocols, with examples that make the book a practical guide in addition to its coverage of theory.
Table of Contents (20 chapters)
19
Index

12.1 The NVT Protocol

NVT is an acronym for Network Virtual Terminal. NVT is a subset of the Telnet protocol, i.e., it is as if the Telnet protocol consists of two layers: the lower layer called NVT and the upper layer called the main Telnet protocol. The NVT protocol deals with data presentation, i.e., it provides answers to questions such as into which byte should the letter A be transformed in order to be interpreted as A again at the other end of the network connection, or which Telnet protocol command should be generated when the well-known Ctrl + C (^C) combination of characters is keyed in for abnormal termination of a program run from the console.

It is precisely the NVT protocol that is used (to a limited extent) for data presentation in a number of other protocols such as FTP, POP3, SMTP, NNTP, HTTP, etc. Multipurpose Internet Mail Extension (MIME) is basically an extension of this philosophy. This is also the reason why the NVT protocol is discussed in such detail. It is a...