Table of Contents The Internet: Past, Present and Future
TCP/IP Tutorial and Technical Overview

1.1 Introduction

Networks have become a fundamental, if not the most important, part of today's information systems. They form the backbone for information-sharing in enterprises, governmental and scientific groups. That information can take several forms. It can be notes and documents, data to be processed by another computer, files sent to colleagues, and even more exotic forms of data.

Most of these networks were installed in the late 60s and 70s, when network design was the "state of the art" topic of computer research and sophisticated implementers. It resulted in multiple networking models such as packet-switching technology, collision-detection local area networks, hierarchical enterprise networks, and many other excellent technologies.

From the early 70s on, another aspect of networking became important: protocol layering, which allows applications to communicate with each other. A complete range of architectural models were proposed and implemented by various research teams and computer manufacturers.

The result of all this great know-how is that today any group of users can find a physical network and an architectural model suitable for their specific needs. This ranges from cheap asynchronous lines with no other error recovery than a bit-per-bit parity function, through full-function wide area networks (public or private) with reliable protocols such as public packet-switching networks or private SNA networks, to high-speed but limited-distance local area networks.

The down side of this exploding information-sharing is the rather painful situation when one group of users wants to extend their information system to another group of users, who happen to have a different network technology and different network protocols. As a result, even if they could agree on a type of network technology to physically interconnect the two locations, their applications (such as mailing systems) still would not be able to communicate with each other because of the different protocols.

This situation was recognized rather early (beginning of the 70s) by a group of researchers in the US who came up with a new principle: internetworking. Other official organizations became involved in this area of interconnecting networks, such as ITU-T and ISO. All were trying to define a set of protocols, layered in a well-defined suite, so that applications would be able to talk to other applications, regardless of the underlying network technology and the operating systems where those applications run.

Table of Contents Internetworks