Exercise 4-2

4.2. Describe the TCP protocol. How is it related to the IP protocol?

Cisco(2009) states that TCP is stand for Transmission Control Protocol that is a transport Layer (Layer 4) protocol of OSI model (Open Systems Interconnection Reference Model), it is known as a connection-oriented protocol, which means that a connection is established and maintained until such time as the message or messages to be exchanged by the application programs at each end have been exchanged. TCP is responsible for ensuring that a message is divided into the packets that IP manages and for reassembling the packets back into the complete message at the other end.

TCP is related to IP protocol, Techtarget(2009) states that TCP is a set of rules (protocol) used along with the Internet Protocol (IP) to send data in the form of message units between computers over the Internet. While IP takes care of handling the actual delivery of the data, TCP takes care of keeping track of the individual units of data that a message is divided into for efficient routing through the Internet.

For example, when an HTML file is sent to you from a Web server, the Transmission Control Protocol (TCP) program layer in that server divides the file into one or more packets, numbers the packets, and then forwards them individually to the IP program layer. Although each packet has the same destination IP address, it may get routed differently through the network. At the other end (the client program in your computer), TCP reassembles the individual packets and waits until they have arrived to forward them to you as a single file.



References:
Cisco(2009). “Internet Protocols”. Received 18th March, 2009 from URL - http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Internet-Protocols.html#wp4145
Techtarget(2009). “TCP”. Received 15th March, 2009 from URL - http://searchnetworking.techtarget.com/dictionary/definition/what-is-TCP.html