- A transmitter transmits the frame.
- Transmitter wait for the acknowledgement for fixed period of time.
- On receiving valid frame, receiver send back an acknowledgement for next frame.
- On receiving acknowledgement transmitter transmit next frame.
- If sender not received any acknowledgement within time duration it re-transmit the same frame.
- The rate of transmission depends on the processing power of the receiver.
Example of Stop and Wait protocol.
|Frame Sender||Frame Receiver|
|Frame(0) transmitted||Acknowledgement Frame(1)|
|Frame(1) transmitted||Acknowledgement Frame(2)|
|Frame(2) transmitted||No Acknowledgement within time|
|Frame(2) re-transmitted||Acknowledgement Frame(3)|
This method is ineffective when the size of the frame is large.
What if the size of the frame is large?
- The transmitter divides large messages into smaller frames.
- Then transmit these smaller frames.