毕业设计(论文) TCP协议中的流量控制和拥塞控制研究
院别数学与统计学院
专业名称信息与计算科学
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TCP协议中的流量控制和拥塞控制研究
摘要
计算机网络技术是当今发展最迅速的计算机技术之一，而保证网络稳定可靠运行的关键是计算机网络协议。TCP协议作为网络协议中的核心协议之一，其重要性更是不言而喻，因而对于该协议的研究与完善是促进网络发展的重要手段之一。
随着互联网规模和互联网应用的快速增长，网络拥塞和数据冲突问题已引起人们密切的关注。拥塞控制与流量控制技术针对网络中的拥塞和数据冲突而成为网络领域的核心技术。其中流量控制的对象是接收端，目的是使发送端的发送速率不超过接收端的接收能力；拥塞控制的对象是网络环境，目的是使负载不超过网络的传送能力。
TCP的流量控制主要依赖于滑动窗口，通过流量约束，减少接收端出的数据流失，提高发送效率，充分利用接收端资源。
TCP的拥塞控制主要原理依赖于一个拥塞窗口(cwnd)来控制，窗口值的大小就代表能够发送出去的但还没有收到ACK的最大数据报文段，显然窗口越大那么数据发送的速度也就越快，但是也就越可能使得网络出现拥塞，如果窗口值为1，那么就简化为一个停等协议，每发送一个数据，都要等到对方的确认才能发送第二个数据包，显然数据传输效率低下。TCP拥塞控制算法就是要在这两者之间权衡，选取最的cwnd值，从而使得网络吞吐量最大化且不产生拥塞。
本文首先对TCP协议的发展做了简要的概述，然后分析了TCP协议的报文段格式和结构，TCP的数据传输过程，接着讨论了TCP的流量控制机制，最后针对TCP 的重点部分拥塞控制进行了分析，讨论了几个TCP拥塞控制算法。
关键词：TCP协议，流量控制，拥塞控制
The Flow Contral and Congestion Control in TCP Protocol
Author: Etvgbd
Tutor: Rtvghhh
Abstract
Computer network technology is one of the most rapidly developing of computer technology today,and the computer network protocols is the key to ensure the network is stable and reliable operation. TCP protocol, as one of the core protocols of the network protocol,is vary important, so to research and improve the protocol is one of the important means to promote the development of the network.
With the rapid growth of Internet scale and the Internet application, network congestion and data conflict problem has aroused the concern of the people closely. Congestion control and flow control technology, according to the theory of network congestion and data conflict has become the core technology in the field of network. The flow control object is the receiver, the purpose is to make the sending rate does not exceed the capacity at the receiving end. Congestion control object is the network environment, the purpose is to make the transfer of a loaded with no more than the network capacity.
TCP flow control is mainly depended on the sliding window, by flow constraints, and reduce the loss of data at the receiving end, to improve the transmission efficiency, make full use of the receiver.
The main principle of TCP congestion control relies on a congestion window (cwnd) to control the window size value represents the ability to send
out but not yet received the maximum data packet ACK Duan, clear window, so the greater the speed of data sent the faster, but also more likely to make the network congestion occurs, if the window is 1, then reduced to a stop such agreement, each sending a data, must wait for confirmation of the other party can send a second packet, the data clearly transmission efficiency is low. TCP congestion control algorithm is to balance between these two, choose the best cwnd value, allowing the network to maximize throughput and does not create congestion.
Firstly, the development of the TCP protocol a brief overview, and then analyzed the structure of TCP protocol, TCP data transfer process, followed by a discussion of the TCP flow control mechanism, the key part of the final for the TCP congestion control are analyzed, discussed Several TCP congestion control algorithm.
Key Words :TCP protocol, Flow control,Congestion control