Transport Layer The Transport Layer is the second and uppermost layer of the OSI (Open Systems Interconnection) reference model. It deals with the actual da...
Transport Layer
The Transport Layer is the second and uppermost layer of the OSI (Open Systems Interconnection) reference model. It deals with the actual data transfer between two communicating devices, which are typically computers.
Key functions of the Transport Layer:
Flow control: The Transport Layer establishes, maintains, and terminates flows of data packets between the source and destination. It ensures that the data is delivered correctly and in the correct order.
Error detection and correction: The Transport Layer incorporates error detection and correction mechanisms into the data packets. It detects errors in the data and re-transmits the packets to ensure that the destination receives the data correctly.
Flow sequencing: The Transport Layer ensures that data packets are transmitted in the correct sequence. It verifies that the packets are received in the same order they were sent.
Transport Layer mechanisms:
Sliding Window: The Transport Layer uses a sliding window mechanism to control the flow of data. The window size is initially set by the sender and can be adjusted by the receiver. This mechanism ensures that the data is transmitted in a controlled manner and that the receiver has enough space to receive the packets without being overwhelmed.
Sequence numbers: Each data packet includes a sequence number that identifies its position in the flow. The Transport Layer uses these sequence numbers to verify that the packets are received in the correct order.
Acknowledgement: The Transport Layer uses acknowledgments from the receiver to indicate that the data has been received correctly. This allows the sender to continue sending more data without having to retransmit packets that have already been received.
Examples:
When you open a file in a word processor, the operating system (OS) uses the Transport Layer to send the file data to the word processor.
When you receive an email, the email client uses the Transport Layer to receive the email data from the email server.
When you watch a video on a streaming service, the video and audio data are transmitted from the streaming server to your computer through the Transport Layer