RFC793 TCP 协议

PREFACE（引言）

1. INTRODUCTION （简介）

   1.1 Motivation （动机）
   1.2 Scope （范围）
   1.3 About This Document （关于此文档）
   1.4 Interfaces （接口）
   1.5 Operation （操作）

2. PHILOSOPHY （设计理念）

   2.1 Elements of the Internetwork System （网络系统要素）
   2.2 Model of Operation （操作模型）
   2.3 The Host Environment （HOST 环境）
   2.4 Interfaces （接口）
   2.5 Relation to Other Protocols （和其他协议的关系）
   2.6 Reliable Communication （可靠通信）
   2.7 Connection Establishment and Clearing （链接的建立和清除）
   2.8 Data Communication （数据通信）
   2.9 Precedence and Security （优先权和安全性）
   2.10 Robustness Principle （健壮性原则）

3. FUNCTIONAL SPECIFICATION （功能规范）

   3.1 Header Format （Header 格式）
   3.2 Terminology （专业术语）
   3.3 Sequence Numbers （序号说明）
   3.4 Establishing a connection （建立一个链接）
   3.5 Closing a Connection （断开一个链接）
   3.6 Precedence and Security （优先级和安全性）
   3.7 Data Communication （数据通信）
   3.8 Interfaces （接口）
   3.9 Event Processing （事件处理）

GLOSSARY （术语表）

REFERENCES （引用）

---

                                PREFACE



This document describes the DoD Standard Transmission Control Protocol
(TCP).  There have been nine earlier editions of the ARPA TCP
specification on which this standard is based, and the present text
draws heavily from them.  There have been many contributors to this work
both in terms of concepts and in terms of text.  This edition clarifies
several details and removes the end-of-letter buffer-size adjustments,
and redescribes the letter mechanism as a push function.

                                                           Jon Postel

                                                           Editor

---

INTRODUCTION

The Transmission Control Protocol (TCP) is intended for use as a highly
reliable host-to-host protocol between hosts in packet-switched computer
communication networks, and in interconnected systems of such networks.

传输控制协议(TCP)的目的，是在 包交换计算机通信网络 和 此类网络的互连系统中，
为主机间的通信提供可靠的协议。

This document describes the functions to be performed by the
Transmission Control Protocol, the program that implements it, and its
interface to programs or users that require its services.

本文档描述传输控制协议要执行的功能、实现该协议的程序、以及需要其服务的程序或用户的接口。

Motivation

Computer communication systems are playing an increasingly important
role in military, government, and civilian environments. This
document focuses its attention primarily on military computer
communication requirements, especially robustness in the presence of
communication unreliability and availability in the presence of
congestion, but many of these problems are found in the civilian and
government sector as well.

计算机通信系统在军事、政府和民用环境中发挥着越来越重要的作用。
本文件主要关注军用计算机通信需求，特别是在通信不可靠和存在拥塞时的健壮性和可用性，但其中许多问题也存在于民用和政府部门。

As strategic and tactical computer communication networks are
developed and deployed, it is essential to provide means of
interconnecting them and to provide standard interprocess
communication protocols which can support a broad range of
applications. In anticipation of the need for such standards, the
Deputy Undersecretary of Defense for Research and Engineering has
declared the Transmission Control Protocol (TCP) described herein to
be a basis for DoD-wide inter-process communication protocol
standardization.

随着战略和战术计算机通信网络的发展和部署，提供相互连接的手段和支持广泛应用的标准进程间通信协议至关重要。
考虑到需要这样的标准，负责研究和工程的国防部副部长声明了本文描述的传输控制协议(TCP)，这份协议将作为全局性进程间通信协议标准化的基础。

TCP is a connection-oriented, end-to-end reliable protocol designed to
fit into a layered hierarchy of protocols which support multi-network
applications. The TCP provides for reliable inter-process
communication between pairs of processes in host computers attached to
distinct but interconnected computer communication networks. Very few
assumptions are made as to the reliability of the communication
protocols below the TCP layer. TCP assumes it can obtain a simple,
potentially unreliable datagram service from the lower level
protocols. In principle, the TCP should be able to operate above a
wide spectrum of communication systems ranging from hard-wired
connections to packet-switched or circuit-switched networks.

TCP 是一种面向连接的端到端可靠协议，它被设计成适合于支持多网络应用程序的分层协议层次结构。
有一些计算机链接到不同的网络，但是这些网络之间是互通的。TCP 给这些计算机提供了可靠的内部进程通信。
TCP 下层通信的可靠性是未知的，TCP 假定它可以提供一个简单的，可能不可靠的数据报文服务。
原则上，TCP应该能够在从硬线连接到分组交换或电路交换网络的广泛通信系统频谱之上运行。（大概的意思就是 TCP 应该可以各种硬件之上运行，和运行无关）。

TCP is based on concepts first described by Cerf and Kahn in [1]. The
TCP fits into a layered protocol architecture just above a basic
Internet Protocol [2] which provides a way for the TCP to send and
receive variable-length segments of information enclosed in internet
datagram “envelopes”. The internet datagram provides a means for
addressing source and destination TCPs in different networks. The
internet protocol also deals with any fragmentation or reassembly of
the TCP segments required to achieve transport and delivery through
multiple networks and interconnecting gateways. The internet protocol
also carries information on the precedence, security classification
and compartmentation of the TCP segments, so this information can be
communicated end-to-end across multiple networks.

TCP 是基于 Cerf 和 Kahn 在 [1] 中第一次描述的概念。
TCP 协议是适合分层控制协议的架构的，就在基础的 IP 协议之上（IP 协议为 TCP 提供了一种发送和接收不定长数据的方式。）
internet数据报提供了一种在不同网络中寻址源 tcp 和目标 tcp 的方法。