Explain how communication takes place on Internet. (or) Explain the working of TCP/IP Protocol.

The internet is a network of networks. The success of internet depends upon cooperation among the networks and computers that compose the network. This cooperation is accomplished by a common set of protocols. The protocol that determines how computers connect, send, and receive information on the Internet is Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP consists of about 100 different protocols and new ones are developed and added regularly.

TCP/IP is described as the “language of the Internet”. TCP/IP allows people of different backgrounds to communicate, and it allows many different kinds of computers, from personal computers to mainframes, to exchange information. The two main protocols in the TCP/IP suite are TCP/IP. TCP permits communication between the various computers on the internet, while IP specifies how data is routed from computer to computer.

To illustrate TCP/IP working, consider sending an e-mail message. The message is formatted according to the application protocol. Simple Mail Transfer Protocol (SMTP) is used for email message. Assume that TCP/IP software is installed on your computer, the information to be sent split into IP packets, called packets for short, and transmitted over internet. The advantages of the packet transmission are:

Error recovery:  If a packet gets corrupted, only that packet needs to be resent, not the entire message.

Load distribution: If one area of the network is congested, packets can be rerouted to less busy areas.

Flexibility:          If a network experiences a failure or disruption in one area, packets can be rerouted easily.

Each packet of data contains the following information along with data.

Address of the sending computer. (Source computer)

Address of the receiving computer. (Destination computer)

Sequence number indicating where the packet fits in the original message.

Error checking information to ensure that the packet is not corrupted.

The packets are reassembled after being received at the destination computer. A message is sent from the destination computer to the sending computer to resend any missing or corrupted packets. This method is known as packet switching. It is not necessary to send the data packets in sequential order, or even over the same network route. If packets arrived are out of order, the sequence number can be used to reconstruct the original message.