Transmission Control Protocol Introduction

Transmission Control Protocol       

TCP is one of the two original components of the suite the other being  Protocol so the entire suite is commonly referred to as TCP/IP. Whereas IP handles lower-level transmissions from computer to computer as a message makes its way across the Internet, TCP operates at a higher level, concerned only with the two end systems, for example a Web browser and a Web server. In particular, TCP provides reliable, ordered delivery of a stream of bytes from a program on one computer to another program on another computer. Besides the Web, other common applications of TCP include   . Among its other management tasks, TCP controls segment size, flow control, the rate at which data is exchanged, and network traffic congestion

HISTORICAL ORIGIN                                                                                

In May, 1974, the IEEE published a paper entitled "A Protocol for Packet Network Interconnection." The paper'Network function.

IP works by exchanging pieces of information called  A packet is a sequence of  and consists of a header followed by a body. The header describes the packet's destination and, optionally, the  to use for forwarding until it arrives at its final destination. The body contains the data which IP is transmitting.

Due to network congestion, traffic load balancing, or other unpredictable network behavior, IP packets can be  TCP detects these problems, requests retransmission of lost packets, rearranges out-of-order packets, and even helps minimize network congestion to reduce the occurrence of the other problems. Once the TCP receiver has finally reassembled a perfect copy of the data originally transmitted, it passes that datagram to the application program. Thus, TCP abstracts the application's communication from the underlying networking details.

                                      FLOW CONTROL

TCP uses an end-to-end protocol to avoid having the sender send data too fast for the TCP receiver to reliably receive and process it. Having a mechanism for flow control is essential in an environment where machines of diverse network speeds communicate. For example, if a PC sends data to a hand-held PDA that is slowly processing received data, the PDA must regulate data flow so as to not be overwhelmed. Forcing Data Delivery

Normally, TCP waits for the buffer to exceed the maximum segment size before sending any data. This creates serious delays when the two sides of the connection are exchanging short messages and need to receive the response before continuing. For example, the login sequence at the beginning of a session begins with the short message "Login," and the session cannot make any progress until these five characters have been transmitted and the response has been received. This process can be seriously delayed by TCP's normal behavior when the message is provided to TCP in several send calls

Reliable, a technique known as positive acknowledgment with retransmission is used to guarantee reliability of packet transfers. This fundamental technique requires the receiver to respond with an acknowledgment message as it receives the data. The sender keeps a record of each packet it sends, and waits for acknowledgment before sending the next packet. The sender also keeps a timer from when the packet was sent, and retransmits a packet if the timer expires. The timer is needed in case a packet gets lost or corrupted.

TCP consists of a set of rules: for the protocol, that are used with the Internet Protocol, and for the IP, to send data "in a form of message units" between co

   described an internetworking protocol for sharing resources using packet-switching among the nodes. A central control component of this model was the Transmission Control Program that incorporated both connection-oriented links and datagram services between hosts. The monolithic Transmission Control Program was later divided into a modular architecture consisting of the Transmission Control Protocol at the connection-oriented layer and the Internet Protocol at the internetworking  layer. The model became known informally as TCP/IP, although formally it was henceforth called the Internet Protocol Suite.

HARDWARE IMPLEMENTATION

One way to overcome the processing power requirements of TCP is to build hardware implementations of it, widely known as TCP  The main problem of TOEs is that they are hard to integrate into computing systems, requiring extensive changes in the operating system of the computer or device. The first company to develop such a device was Alacritech

NETWORK FUNCTION

TCP provides a communication service at an intermediate level between an application program and the . That is, when  desires to send a large chunk of data across the Internet using IP, instead of breaking the data into IP-sized pieces and issuing a series of IP requests, the software can issue a single request to TCP and let TCP handle the IP details.

IP works by exchanging pieces of information called  packet is a sequence of bytes and consists of a header followed by a body. The header describes the packet's destination and, optionally, the routers to use for forwarding until it arrives at its final destination. The body contains the data which IP is transmitting.

Due to network congestion, traffic load balancing, or other unpredictable network behavior, IP packets can be . TCP detects these problems, requests retransmission of lost packets, rearranges out-of-order packets, and even helps minimize network congestion to reduce the occurrence of the other problems. Once the TCP receiver has finally reassembled a perfect copy of the data originally transmitted, it passes that datagram to the application program. Thus, TCP abstracts the application's communication from the underlying networking details.