What Are The Services Provided To The Transport Layer?

Open System interconnection (OSI) is a model of communications between cooperating devices. It defines a seven layer architecture of communication functions and Transport layer is one of them.

Transport layer is layer number four of the OSI model. Purpose of transport layer is to provide transparent transfer of data between the communication bodies.. Actually, It acts as the interface between the higher application oriented layers ( Session Layer, Application Layer, Presentation Layer)  and the underlying network independent protocol layers ( physical Layer, Data Link Layer and Network Layer).

Transport layer protocol gives the guarantee that data will be free of error and it will reach on the destination without nay loss and duplication. Optimizing the network services is also one of the functions of transport layer.

There I usually a requirement that data be exchanged reliably between endpoints. That is, we would like to be assured that all of the data arrive at the destination and that data arrive in the same order in which they were sent. Mechanisms for providing reliability are essentially independent of the nature of the applications. Thus it makes sense to collect those mechanisms in a common layer shared by all applications; this is referred to as the host to host layer or transport layer.