3.2 Internet and CommunicationProtocol – a set of rules governing the way that devices communicate with each other.The computers must talk to each other in a way that the receiving end can understand the message. In order for that to happen, there are sets of rules governing modes of communication. These rules are called protocols.Examples include: FTP, HTTP, POP3, and SMTPPort Number – an application endpoint or process specific communication endpoint attached to an IP address.When you send and receive data from a client or server, you will be sending lots of different types of data. To make sure that the data is dealt with by the correct program, you need to add a port number. Each application will have a port number associate with it. For example, a web server is “port 80” and a Counter-Strike game port is “666”Combining an IP address with a port gives us a “Socket”This is a direct connection to a process or application on a machine:
FTP:File Transfer Protocol (FTP) is a standardnetwork protocol used to copy a filefrom one host to another over TCP/IP-based network such as the internet. FTPworks on port 21HTTP:The Hypertext Transfer Protocol(HTTP) is a networking protocolbehind the World Wide Web. It allowsfor users on the web to exchangeinformation found on web pages.HTTP works on ports 80 & 8080.POP3 & SMTP:Simple Mail Transfer Protocol (SMTP) is an internet standard for sending e-mails across networks. SMTP is specified for “outgoing” mail transport and usesport 25. The protocolfor receiving mail iscalled Post OfficeProtocol 3 (POP3)anduses port 110.
The Main task that each of these protocols do is simple. However, theprotocol itself is made up of several modules each of which is responsible for a certain subtask. All the layers together complete themain task and form the protocol. Idea of dividing a protocol into subtasks can be viewed as a stack structure where each subtask is an individual block.TCP/IP stands for Transmission Control Protocol/Internet Protocol. It defines how electron devices should connect over the internet, and how data should be transmitted between computers.TCP – Transmission Control ProtocolTCP is responsible for breaking data down into packets before they can be sent over a network, and for assembling the packets again when they arrive.IP – Internet ProtocolIP takes care of the communication between computers. It is responsible for addressing, sending and receiving the data packets over the Internet.
Communication between computers on a network is done through protocol Suits.The most widely used and available suit is TCP/IP. A protocol suit consists of a layer architecture where each layer depicts some functionality which can be carried out by a protocol.