The TCP/IP Reference Model




It is a carefully designed network model which characterizes the dissemination of information across networks or from origin to destination. The TCP/IP reference model has four layers which are the Network Layer, Internet Layer, Transport Layer and the application layer. All these layers are coordinated and perform specific functions in the network model.




The Network layer

It is also known as the Host to Host layer and is the lowest layer in the TCP/IP reference model. It is not constant in its operations and may vary from network to network or host to host. The network layer allows the transmission of the packets by being connected to the host.


The Internet Layer

It is the second layer which determines a packet switching network. It is a connectionless internetwork layer that allows the packets to be transmitted individually to the terminal and connects the entire structure. It is also coordinated with the Internet protocol and sends the received packets in a different arrangement.


Transport layer

The third layer of the TCP/IP reference model determines the transmission of data from a single line or parallel lines. It is in this layer where the applications can be read or written and also inclusive of header information.

The transport layer is responsible for segmenting the data or multiplexing and can arrange for a subsequent transmission of the packets. The layer makes it possible for the packets to be manageable by the network layer as it splits the data into smaller units.


Application layer

It is the highest layer in the reference model where several applications are described. These applications include the DNS, SMTP, FTP and the Telnet. The Domain Name Server (DNS), is responsible for converting the Internet protocol address to a textual address. It is efficient for the servers or hosts with a connection across the network. The Simple Mail Transport Protocol (SMTP), conveys electronic mail that is directed through a route between an origin and destination. The File Transfer Protocol (FTP), is useful for transferring data within a variety of computer users across a network connection. The TELNET is a point to point protocol of communication responsible for connections to a remote machine.




The TCP/IP reference model has several benefits that make its operations efficient. It is scalable, operates independently and has a server/ client structure. It is also important in establishing network connections between computers and supports a variety of routing protocols.

It also has a few downsides such as difficulties in replacing the protocol. The reference model has not clearly outlined its protocols, services, and interfaces. The transport layer may not guarantee safe delivery of packets to their destination.