What is the Transport Layer Responsibilities & Function

What is the Transport Layer Responsibilities & Function

In this we will describe What is the Transport Layer Responsibilities & Function in the administration of data transport in end-to-end communication.
What is the Transport Layer ?
The transport layer, or layer four of the OSI model, manages the flow of information from one network node to another. Its main function is to establish a temporary communication session between two applications and to transmit data between them. TCP / IP uses two protocols to achieve this:

• Transmission Control Protocol (TCP)
• User Datagram Protocol (UDP)

Responsibilities OF the Transport Layer

The tasks of the transport layer are as follows:

• Track individual conversations between applications on the source and destination hosts : In the transport layer, each set of data that flows between a source and a destination application is known as a “conversation”. A host can have several applications that communicate over the network simultaneously
• Segment data for administration and reassemble segments at the destination : Transport layer protocols have services that segment application data into blocks of an appropriate size. These services include the necessary encapsulation in each piece of data.
• Identify applications : The transport layer assigns an identifier to each application, called a port number. All software processes that require access to the network are assigned a unique port number for that host.

Multiplexing Conversation

Sending some types of data (such as a video stream) through a network, such as a full flow of communication, can consume all available bandwidth. This will prevent other communications from occurring at the same time. It could also hinder error recovery and re-transmission of damaged data.

How to solve it? through the segmentation of data into smaller parts, allowing multiple communications of different users to be interlaced (multiplexed) on the same network.

DATA SEGMENTATION

It allows multiple different communications from several different users to be interlaced (multiplexed) on the same network simultaneously.

It provides the means to send and receive data during the execution of several applications.

A header is added to each segment to identify it.

RELIABILITY OF THE TRANSPORT LAYER

While the IP deals only with the structure, addressing and packet routing. Transport protocols specify the way in which messages are transferred between hosts . TCP / IP provides two transport layer protocols: the transmission control protocol (TCP) and the user datagram protocol (UDP). IP uses these transport protocols to enable communication and data transfer between hosts.

TCP is considered a reliable and complete transport layer protocol, as it ensures that all data reaches the destination. However, this requires additional fields in the TCP header that increase the packet size and also the delay. In contrast, UDP is a simpler transport layer protocol, although it does not provide reliability. Therefore, it has fewer fields and is faster than TCP. We will analyze it later.