TCP in Networking | TCP Protocol

Transport Layer Protocols-


There are mainly two transport layer protocols that are used on the Internet-



  1. Transmission Control Protocol (TCP)
  2. User Datagram Protocol (UDP)


In this article, we will discuss about Transmission Control Protocol (TCP).

Learn about User Datagram Protocol.


Transmission Control Protocol-


  • TCP is short for Transmission Control Protocol.
  • It is a transport layer protocol.
  • It has been designed to send data packets over the Internet.
  • It establishes a reliable end to end connection before sending any data.


Characteristics Of TCP-




TCP is a reliable protocol.


This is because-

  • It guarantees the delivery of data packets to its correct destination.
  • After receiving the data packet, receiver sends an acknowledgement to the sender.
  • It tells the sender whether data packet has reached its destination safely or not.
  • TCP employs retransmission to compensate for packet loss.


Read More- TCP Retransmission




TCP is a connection oriented protocol.


This is because-

  • TCP establishes an end to end connection between the source and destination.
  • The connection is established before exchanging the data.
  • The connection is maintained until the application programs at each end finishes exchanging the data.




TCP handles both congestion and flow control.


  • TCP handles congestion and flow control by controlling the window size.
  • TCP reacts to congestion by reducing the sender window size.


Read More- TCP Congestion Control




TCP ensures in-order delivery.


  • TCP ensures that the data packets get deliver to the destination in the same order they are sent by the sender.
  • Sequence Numbers are used to coordinate which data has been transmitted and received.




TCP connections are full duplex.


  • TCP connection allows to send data in both the directions at the same time.
  • So, TCP connections are Full Duplex.




TCP works in collaboration with Internet Protocol.


  • A TCP connection is uniquely identified by using-

Combination of port numbers and IP Addresses of sender and receiver.

  • IP Addresses indicate which systems are communicating.
  • Port numbers indicate which end to end sockets are communicating.
  • Port numbers are contained in the TCP header and IP Addresses are contained in the IP header.
  • TCP segments are encapsulated into an IP datagram.
  • So, TCP header immediately follows the IP header during transmission.




TCP can use both selective & cumulative acknowledgements.


  • TCP uses a combination of Selective Repeat and Go back N protocols.
  • In TCP, sender window size = receiver window size.
  • In TCP, out of order packets are accepted by the receiver.
  • When receiver receives an out of order packet, it accepts that packet but sends an acknowledgement for the expected packet.
  • Receiver may choose to send independent acknowledgements or cumulative acknowledgement.
  • To sum up, TCP is a combination of 75% SR protocol and 25% Go back N protocol.




TCP is a byte stream protocol.


  • Application layer sends data to the transport layer without any limitation.
  • TCP divides the data into chunks where each chunk is a collection of bytes.
  • Then, it creates a TCP segment by adding IP header to the data chunk.
  • TCP segment = TCP header + Data chunk.




TCP provides error checking & recovery mechanism.


TCP provides error checking and recovery using three simple techniques-

  1. Checksum
  2. Acknowledgement
  3. Retransmission


Also Read- Checksum


To gain better understanding about Transmission Control Protocol,

Watch this Video Lecture


Next Article- TCP Header


Get more notes and other study material of Computer Networks.

Watch video lectures by visiting our YouTube channel LearnVidFun.

TCP in Networking | TCP Protocol
Article Name
TCP in Networking | TCP Protocol
TCP in Networking stands for Transmission Control Protocol. TCP is a transport layer protocol. TCP Protocol has been designed to send data packets reliably over the Internet. Characteristics of TCP are discussed.
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Gate Vidyalay
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