In the early days of networking development, networks was chaotic. The protocols that were used to transfer the data from one computer to another computer were developed by hardware manufactures. Each vendor developed different proprietary protocols to support their own products. Some manufacturers even had multiple protocols, because protocols were developed independently for different computer platforms. The main problem with the protocols was, the protocols that were developed by one vendor were not compatible with other vendor networks. In this case, users had to buy all the devices of same to company to run a network.
As the usage of computers increased all over the world, there was a need to use a common protocol to communicate across the world. If many …show more content…
The network layer provides a mechanism called routing to achieve this.
• Network layer includes services such as error control, packet sequence control and flow control.
• Splits large packets into smaller ones.

iv. Transport Layer
This layer is concerned with functions related to the reliable and unreliable delivery of data from source to destination. Transport layer splits data into smaller packets as soon as data is sent by a computer on a network so that packets can be resent if any of them fail to reach the specified destination.

The transport layer provides transparent data transfer between the end devices and controls flow of packets. This layer is responsible for ensuring complete data transfer and for the end-to-end error recovery. Transport layer transmits whole data in the predefined order and ensures flow control and error control during transmission of data from source to destination.

Figure 1.2.6: Transport Layer
Source: http://www.studytonight.com/computer-networks/osi-model-transport-layer

Functions of Transport