What task are performed by the transport layer?

1. Transport layer ensure data is sent & received successfully between two computers. If data is sent incorrectly this layer asks for re-transmission of data.

2. If the message is too large it breaks the message (from session layer) into smaller datagram and appends appropriate unit header information.

3. It ensures reliable service to the top three layers.

4. By providing session layer with a reliable message transfer service it hides all the detailed network information from the session layer.