In the OSI (Open System Interconnection) model, the transport layer is one of the seven layers and it is responsible for the end to end communication between the sender and receiver over the internet. It provides logical communication between the sender and receiver and ensures the end to end delivery of the packet.
The transport layer main protocols are as follows −
TCP (Transmission Control Protocol)
UDP (User Datagram Protocol)
SCTP (Stream Control Transmission Protocol)
RDP (Reliable Data Protocol)
RUDP (Reliable User Datagram Protocol)
The responsibilities of the transport layer are as follows −
It provides a process to process delivery or end to end delivery of the entire message from the sender to the receiver.
This layer checks for errors during transmission.
It controls the flow control mechanism and prevents data loss due to the speed mismatch of the sender and receiver.
This layer divides the stream of bytes received from the upper layer into segments at the sender side and reassembles at the receiver side.
The main challenges to designing a transport layer protocol are given below −
Dynamic Topology − Technology is changing day by day and it affects the performance of the transport layer and will be slightly affected by these changes.
Power and Bandwidth constraints − In a wireless network, two main constraints of power and bandwidth are faced. These constraints affect the transport layer.
To handle congestion control, reliability and flow control separately − If we handle congestion control, reliability and flow control separately then the performance of the transport layer is increased. But to handle these separately is the additional control overhead.