The TCP/IP reference model of networking consists of 5 layers. It's named as TCP/IP because of its two main and popular protocols, namely TCP (Transmission Control Protocol) used in Transport Layer, and IP (Internet Protocol) used in Internet Layer. These layers are as follows -
- Application Layer
- Transport Layer
- Internet Layer
- Host - to - Network Layer
Application Layer
Unlike the OSI model, the TCP/IP does not have any Session Layer or Presentation Layer, instead it has only one layer on top of the transport layer, which is known as the Application Layer. The application layer is responsible for sending and delivering the messages across applications. Examples include emails, social chats etc. where a message is sent from an application on one host, to the same or different application on another host. The protocols responsible for accurate, timely and secure delivery of messages include HTTP, SMTP, TELNET, FTP etc. SMTP is used in email applications, HTTP is used to deliver content across websites to any host on the internet.
Transport Layer
The Transport Layer is responsible for end to end communication. It takes care of errors, lots data packets from the network layer, etc. In other words, it makes sure that the network layer sends the information correctly to the other end of the network channel. There are two main types of protocols used in transport layer - TCP, which is connection oriented and reliable, and UDP - which is connection-less and unreliable.
Internet Layer
The Internet Layer is often referred to as the Network Layer in TCP/IP reference model. It converts data received from the transport layer and converts them into network packets which can be sent independently across the network, even in an out-of-order sequence. The most popular protocol used in the internet layer in TCP/IP reference model is the IP (Internet Protocol). This protocol is also responsible for routing the packets from source to destination.
Host - to - Network Layer
The Data Link Layer and the Physical Layer from the OSI model are merged together n the TCP/IP reference model and is together called as the Host-to-Network Layer. This layer is responsible for transmitting the bits and bytes via physical media like optical fibre, radio waves etc. Protocols of this layer also provides error detection and correction capabilities.
Tuesday, 20 September 2016
