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Specification of Internet Transmission Control Program (RFC0675) Disclosure Number: IPCOM000003726D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2019-Feb-14
Document File: 70 page(s) / 88K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

V. Cerf: AUTHOR [+2]

Related Documents

10.17487/RFC0675: DOI


The first detailed specification of TCP; see RFC 793.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 3% of the total text.

Network Working Group Vinton Cerf Request for Comments: 675 Yogen Dalal NIC: 2 Carl Sunshine INWG: 72 December 1974


December 1974 Version


This document describes the functions to be performed by the internetwork Transmission Control Program [TCP] and its interface to programs or users that require its services. Several basic assumptions are made about process to process communication and these are listed here without further justification. The interested reader is referred to [CEKA74, TOML74, BELS74, DALA74, SUNS74] for further discussion.

The authors would like to acknowledge the contributions of R. Tomlinson (three way handshake and Initial Sequence Number Selection), D. Belsnes, J. Burchfiel, M. Galland, R. Kahn, D. Lloyd, W. Plummer, and J. Postel all of whose good ideas and counsel have had a beneficial effect (we hope) on this protocol design. In the early phases of the design work, R. Metcalfe, A. McKenzie, H. Zimmerman, G. LeLann, and M. Elie were most helpful in explicating the various issues to be resolved. Of course, we remain responsible for the remaining errors and misstatements which no doubt lurk in the nooks and crannies of the text.

Processes are viewed as the active elements of all HOST computers in a network. Even terminals and files or other I/O media are viewed as communicating through the use of processes. Thus, all network communication is viewed as inter-process communication.

Since a process may need to distinguish among several communication streams between itself and another process [or processes], we imagine that each process may have a number of PORTs through which it communicates with the ports of other processes.

Since port names are selected independently by each operating system, TCP, or user, they may not be unique. To provide for unique names at each TCP, we concatenate a NETWORK identifier, and a TCP identifier with a port name to create a SOCKET name which will be unique throughout all networks connected together.

Cerf, Dalal & Sunshine [Page 1]

RFC 675 Specification of Internet TCP December 1974

A pair of sockets form a CONNECTION which can be used to carry data in either direction [i.e. full duplex]. The connection is uniquely identified by the <local socket, foreign socket> address pair, and the same local socket can participate in multiple connections to different foreign sockets [see Section 2.2].

Processes exchange finite length LETTERS as a way of communicating; thus, letter boundaries are significant. However, the length of a letter may be such that it must be broken into FRAGMENTS before it can be transmitted to its destination. We assume that the fragments will normally be reassembled into a letter before being passed to the receiving process. Throughout this document, it is legitimate to assume that a fragment contains all or a part of a letter, but that a fragment never contains parts of more than one letter.

We specifically...