#TechTalk: What is Transmission Control Protocol (TCP)?

It is very recommendable for everyone to be highly conversant with your computer settings so that you are able to navigate your way past those settings when troubleshooting a network problem. TCP which stands for Transmission Control Protocol is one of those terms you will definitely come across on your computer settings!!.

By Cisco Eng. Shingie Lev Muringi 

Now let’s dissect the role played by this protocol during your communication processes. To those who are well versed with telecommunications, you will understand that TCP is a Transport Layer protocol found on the Layer4 of the OSI7 Layer Model. The major duty of TCP is to ensure the successful delivery of data packets between applications.

A good example where TCP is used is the protocol’s integration on SMS communication platforms on our mobile phones.  The other rival of TCP is UDP which stands for User Datagram Protocol, but TCP is the most preferred transport layer protocol and here is why??

TCP is considered a reliable, full-featured transport layer protocol, which ensures that all of the data arrives at the destination. In contrast, UDP is a very simple transport layer protocol that does not provide for any reliability.

As previously stated, TCP is considered a reliable transport protocol, which means that TCP includes processes to ensure reliable delivery between applications through the use of acknowledged delivery. TCP transport is analogous to sending packages that are tracked from source to destination. If a FedEx order is broken up into several shipments, a customer can check online to see the order of the delivery.


The OSI7 Layer Model which is one of the most important Network Protocol Stacks is use today

With TCP, the three basic operations of reliability are:

  • Tracking transmitted data segments
  • Acknowledging received data
  • Retransmitting any unacknowledged data

TCP breaks up a message into small pieces known as segments. The segments are numbered in sequence and passed to the IP process for assembly into packets. TCP keeps track of the number of segments that have been sent to a specific host from a specific application. If the sender does not receive an acknowledgement within a certain period of time, it assumes that the segments were lost and retransmits them.

Only the portion of the message that is lost is resent, not the entire message. On the receiving host, TCP is responsible for reassembling the message segments and passing them to the application. The File Transfer Protocol (FTP) and the Hypertext Transfer Protocol (HTTP) are examples of applications that use TCP to ensure data delivery.

These reliability processes place additional overhead on network resources due to the processes of acknowledgement, tracking, and retransmission. To support these reliability processes, more control data is exchanged between the sending and receiving hosts. This control information is contained in a TCP header.

The battle for relevance continues…follow Shingie Levison Muringi our Technology Research Specialist and Sub Editor on Twitter @ShingieMuringi1, Email [email protected] or direct Cell: 0775 380 652 for all the latest trending technological issues in and outside Zimbabwe.


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