Network interconnection and gateways (original) (raw)

1990, IEEE Journal on Selected Areas in Communications

As computer networks proliferate, the importance of interconnecting networks increases. Major technical issues that must be solved include selection of a protocol level at which to interconnect, addressing, routing, fragmentation, and congestion control. Often, a specialized gateway device is used to interconnect networks and implement any necessary internet protocols. Two leading alternatives have been developed by the DARPA Internet community (datagram internet protocol) and by the CCITT for public data networks (concatenation of virtual circuits). The new I S 0 standards encompass both approaches, but providing interoperability between them is still a problem. I. INTRODUCTION S computer networks proliferate, the importance of A interconnecting networks increases. The recent explosion in the numbers of personal computers is leading to even greater growth in the local area network (LAN) area. Interconnecting these diverse networks into an internet presents many technical problems, and may be pursued in many ways [9], [16], [31], [32], [37]. The term "network interconnection" has been used broadly to mean any technique which enables systems on one network to communicate with or make use of services of systems on another network. In this paper, we shall explore this full range of meanings, but we shall focus on the problem of providing general-purpose end-to-end communication at the network level in the protocol hierarchy, rather than the additional problems of integrating services at higher protocol levels. Networks differ in geographic scope, type of using organization, types of services to be provided, and transmission technology. This leads to a variety of specific communication protocols and interfaces being used, at least at the lower levels, in different nets. There are good technical and marketing reasons for these different solutions, so diversity in network technologies is likely to persist. This suggests that for a network interconnection strategy to succeed, it must accommodate the autonomy and differences of individual networks to the greatest extent possible. We shall see to what extent this can be accomplished in what follows. We first consider the major technical problems of network interconnection, including stepwise versus endpoint services, level of interconnection, addressing, routing, fragmentation, and congestion control, ending with a summary of functions performed by the "gateway" be-Manuscript