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Transport Services and Protocols
- Provide logical communication between application processes running on different hosts
- Logical communication: The two connecting sides; the sender and the receiver are logically connected to each other by a direct link
- In real life hosts may be hundreds of kilometers apart but in a logical view they are directly connected
- Transport protocols provides communication services directly to applications running on end systems
- Role of Transport Protocols:
- Send side:
- Breaks application-layer messages into smaller chunks called segments
- Passes these segments to the network layer
- Receive side:
- Reassembles received segments into the original message
- Delivers the reassembled message to the application layer
- Transport protocol available to apps: TCP, UDP
Transport layer vs. Network layer
- Network Layer → Provides logical communication between hosts
- Transport Layer → Provides logical communication between processes
Multiplexing and Demultiplexing
Multiplexing
- When a process sends data to transport layer through sockets, transport layer is going to:
- multiplex the data and put it in segments
- add information into the transport layer header that is going to be used later for demultiplexing
Demultiplexing