1. Sliding Window Protocols

2. Piggybacking Is a bi-directional data transmission technique. Frame arrives to destination • the ack attached to an outgoing data frame (using "ack" field in header).

3. Piggybacking

4. Piggybacking Advantages: More efficient (Why?) Cost (1 bit) Disadvantages: How long to wait for a packet to piggyback? There is a problem. If the wait for longer than the sender's timeout period, the frame will be retransmitted (How To solve)

5. Piggybacking Receiver timeout enable (Individual ACK)

6. Sliding Window Protocols They are bidirectional protocols One-bit sliding window protocol Go back N protocol Selective repeat protocol

7. Sliding Window Protocols Two stations, A and B, connected via a full-duplex link Each side needs to send the data and acknowledgments to the other. ACK includes number of next frame expected Frames have sequence number 0 to maximum 2n- 1

8. A Sliding Window Size of One

9. Sliding Window Protocols Sender & receiver have buffer size of W transmitter sends up to W frames without ACK Window full (maximum window size reached)  shut off network layer

10. Sliding Window Diagram

11. Sliding Window Example

12. One-bit Sliding Window Protocol Stop –and-Wait (What is meaning?) The maximum size of sender and receiver windows (?) Sequence number (0,1)

13. One-bit Sliding Window Protocol

14. One-bit Sliding Window Protocol

15. One-bit Sliding Window Protocol

16. Go Back N Protocol Sender’s window size is W (W >1) It needs for multiple timers each outstanding frame

17. Go Back N Protocol 5 6 6 7

18. Go Back N Protocol

19. Go Back N Protocol