Explain the TCP Service Model in Computer Network

In TCP service, the sender and receiver needs to create endpoints called sockets. Each socket has an address which is made up of two parts.

  • An IP address of the host.

  • A port number that is 16 bit local to host (source or destination)

Both are collectively called socket addresses. A port is the TCP name for TSAP (Transport Service Access Point). It is essential to create a link between the sockets of the sender & receiver. Connections are used as identifiers at both ends. It can use the same socket for greater than one connection at a time.

We explain some of the sockets calls with their respectful meaning in the following table. It also should know that TCP does not support multicasting & broadcasting.

Different Socket Calls

The table given below explains the socket calls in TCP service model −

Socket Calls
It creates a new socket call connection.
It gives a local location to a socket.
In response to making a new connection, and it shows a willingness to accept new connections.
It can block the caller unit when a connection attempt arrives.
It can send data over the connection.
It can receive data over the connection.
It can attempt to make a connection.
It can release the connection.


The message boundaries are not maintained end to end. When an application reaches information to TCP, and an application needs that data to be shared directly, it sets the PUSH Flag, forcing the TCP to send information without any interruption.


But when TCP doesn't send the data received from the above application layer, it is collected for some time before sending. That is called Buffering.

Urgent Data

The sending application puts some regulation data in the data flow and provides it to TCP, and then an urgent Flag is set. Therefore, TCP will break buffering information and send it directly.

On reaching the urgent data at destination, the receiving application is disrupted, and the urgent data flow is displayed to it. The last end of urgent data is always indicated for the application to understand that no further is urgent data.

Updated on: 05-May-2021

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