Introduction

ARPA Network Map - December 1969

ARPA Network Map - December 1969

TCP/IP was initially designed to meet the data communication needs of the U.S. Department of Defence. In the late 1960s the Advance Research Projects Agency (ARPA, since renamed to DARPA) began a partnership with Universities and the corporate research sector to design an open, standard protocol suite in order to build multi-vendor networks. The first experimental ARPANET went into operation in 1969. As shown to the right, it consisted of four nodes which were connected together via 56 kbit/s circuits using the Network Control Protocol (NCP) [rfc33, rfc36, rfc78]. The experiment was deemed a success and evolved into the "ARPA Internet". In 1974, the design for a new set of core protocols for ARPANET was proposed in a paper by Vinton G. Cerf and Robert E. Kahn [CK74]. The official name for the set of protocols was "TCP/IP Internet Protocol Suite", commonly referred to as TCP/IP.

TCP/IP is a set of network standards that specify how computers communicate, as well as conventions for inter-connecting networks and routing traffic. The initial specification went through four versions culminating in version 4 in 1979.

TCP is a stream-oriented, reliable transport protocol. This means that the two end-points of the communication are connected together, albeit virtually. Messages between the end-points are transmitted as a stream of octets (bytes). Mechanisms, which will be described in detail later, are employed to make sure that all octets that are sent will be received, and in the order in which they were sent.


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