Transport layer is the first end-to-end layer. Header of the transport layer has information which helps send the message to the corresponding layer at the destination node. The message is broken into packets & may travel by a number of intermediate nodes. This layer takes care of error control & flow control at the source & destination both for the whole message. The responsibilities of the transport layer are following:
- Host-to-host message delivery
- Flow Control
- Segmentation and reassembly