Abstract: TCP is transmission Control Protocol, the Layer4 protocol for communication over both wireline as well as wireless links. It is one of the most widespread of protocols in usage today. All key applications defining the web today, http, email transfer, file transfer, etc. use TCP as the backbone transmission protocol. TCP offers a stream oriented reliable delivery service. Unusually, for a transport layer protocol, it has no explicit support for QoS. Perhaps this is one of the reasons for its success - by eschewing features, it has managed to be simultaneously very efficient and very powerful. Also, it is designed to operate on any standard network layer protocol with as few assumptions as possible. The key feature in TCP is a very sophisticated scheme of congestion management and rate adaptation.There are multiple variants of TCP, each principally differing in the way they execute these features.For a definitive specification of TCP protocol, please see the standard in rfc0793. In the rest of this article, we shall review the theory of TCP congestion avoidance and the different algorithms available for handling the same |