Process-to-Process Communication

• Sending the message from one process to another process
• Also called end-to-end or port-to-port communication
• It uses a port number (16-bit address) to deliver the segmented data to the correct process

Reliability

• Does in-order delivery (loss of data)
• Sequence control
• Loss control
• Duplication control

Encapsulation and Decapsulation

• Encapsulation happens at sender site
• Decapsulation happens at receiver site

Multiplexing and Demultiplexing

• Transport layer at source performs multiplexing
• Transport layer at destination performs demultiplexing

Error Control

• Uses checksum to detect errors
• This is end-to-end

Congestion Control

• Uses open-loop to prevent congestion and close-loop to remove congestion from network once it has occurred

Flow Control

• Provides flow control mechanism between adjacent layers of TCP/IP
• Uses method of sliding window protocol
• Related to first issue, we must prevent losing the data items at consumer site
• Makes sure that data transmitted at any rate is acceptable by both sender and receiver by managing data flow