What are various design issues of the Transport Layer?

Transport layer is responsible for following issues:-

a)     Accepting message segments from the application layer and to divide into packets.

b)     End-to-End Delivery of the packet

c)     Combining packets into message segment at receiver side.

d)     Connection management.

In other words transport layer is responsible for two tasks:-

• Transport and regulate the flow of information from source to destination, reliably and accurately. 
• The end-to-end control:

• Sliding windows.
• Sequencing numbers. 
•  Acknowledgments.
• Segmentation. 
•  Multiplexing.