1.1 Use of TCP/IP

In 1982, the TCP/IP Internet included a few hundred computers
at two dozen sites concentrated primarily in North America. By the Spring of 1992 over 700,000 computer systems attached to the Internet in 39 countries spread across 7 continents, and its size was doubling every ten months. Approximately one third of the 4500 networks that comprised the Internet in 1992 were located outside the U.S.

In addition, most large corporations have chosen TCP/IP protocols for their private corporate internets, many of which are now as large as the connected Internet was ten years ago. TCP/IP accounts for a significant fraction of networking throughout the world. Its use is growing rapidly in Europe, India, South America, and countries on the Pacific rim.

Besides quantitative growth, the past decade has witnessed an important change in the way sites use TCP/IP. Early use focussed on a few basic services like electronic mail, file transfer, and remote login. Now, more users are designing application protocols and building their own application software. In fact, over one fifth of all traffic on the connected Internet arises from private applications. New applications rely on TCP/IP to provide basic transport service. They add rich functionality that has enhanced the Internet environment and has enabled new groups of users to benefit from connectivity.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                