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In the Name of God Computer Networks Chapter 3: The Data Link Layer ( part3)

In the Name of God Computer Networks Chapter 3: The Data Link Layer ( part3). Dr. Shahriar Bijani Shahed University March 2014. References: A . S. Tanenbaum and D. J. Wetherall , Computer Networks (5th Edition ), Pearson Education, the book slides, 2011.

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In the Name of God Computer Networks Chapter 3: The Data Link Layer ( part3)

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  1. In the Name of GodComputer NetworksChapter 3: The Data Link Layer(part3) Dr. ShahriarBijani Shahed University March 2014

  2. References: • A. S. Tanenbaum and D. J. Wetherall, Computer Networks (5th Edition), Pearson Education, the book slides, 2011. • Chapter 6, Data Communications and Computer Networks: A Business User's Approach, 6th Edition • B. A. Forouzan, Data Communications and Networking, 5th Edition, Behrouz A. Forouzan, McGraw Hill, lecture slides, 2012. • McGraw Hill, Data Link Layer, 2004.

  3. Data Link Protocols • Elementary Data Link Protocols • Utopian Simplex Protocol • Simplex Stop-and-Wait Protocol • Error-Free Channel • Simplex Stop-and-Wait Protocol • Noisy Channel • Sliding Window Protocols

  4. Elementary Data Link Protocols Implementation of the physical, data link, and network layers.

  5. Elementary Data Link Protocols Some definitions needed in the protocols to follow. These definitions are located in the file protocol.h. . . .

  6. Elementary Data Link Protocols Some definitions needed in the protocols to follow. These definitions are located in the file protocol.h. . . .

  7. Elementary Data Link Protocols Some definitions needed in the protocols to follow. These definitions are located in the file protocol.h.

  8. Utopian Simplex Protocol (1) A utopian simplex protocol. . . .

  9. Utopian Simplex Protocol (2) A utopian simplex protocol.

  10. Stop and Wait Sender Receiver • Simplest form of reliability • Example: Bluetooth • Problems? • Utilization • Can only have one frame in flight at any time Timeout Timeout Frame Frame Frame ACK

  11. Simplex Stop-and-Wait Protocol for a Noisy Channel (1) A simplex stop-and-wait protocol. . . .

  12. Simplex Stop-and-Wait Protocol for a Noisy Channel (2) A simplex stop-and-wait protocol.

  13. ARQ (Automatic Repeat reQuest) or PAR (Positive Acknowledgement with Retransmission): Protocols in which the sender waits for a positive acknowledgement before advancing to the next data

  14. Sliding Window Protocols • Allow multiple outstanding, un-ACKed frames • Number of un-ACKed frames is called the window Receiver Sender Window Frames ACKs • Made famous by TCP

  15. Sliding Window Protocols (1) A positive acknowledgement, unidirectional with retransmission protocol. . . .

  16. Sliding Window Protocols (2) A positive acknowledgement with retransmission protocol. . . .

  17. Sliding Window Protocols (3) A positive acknowledgement with retransmission protocol.

  18. Sliding Window Protocols (4) A sliding window of size 1, with a 3-bit sequence number. (a) Initially. (b) After the first frame has been sent.

  19. Sliding Window Protocols (5) A sliding window of size 1, with a 3-bit sequence number (c) After the first frame has been received. (d) After the first acknowledgement has been received.

  20. One-Bit Sliding Window Protocol (1) A bidirectional 1-bit sliding window protocol. . . .

  21. One-Bit Sliding Window Protocol (2) . . . A bidirectional 1-bit sliding window protocol.

  22. One-Bit Sliding Window Protocol (3) A bidirectional 1-bit sliding window protocol.

  23. One-Bit Sliding Window Protocol (4) Two scenarios for protocol 4. (a) Normal case. (b) Abnormal case. The notation is (seq, ack, packet number). An asterisk (*) indicates where a network layer accepts a packet

  24. Protocol Using Go-Back-N (1) Pipelining and error recovery. Effect of an error when (a) receiver’s window size is 1 Go-back-N

  25. Protocol Using Go-Back-N (2) Pipelining and error recovery. Effect of an error when (b) receiver’s window size is large. Selective-repeat

  26. Protocol Using Go-Back-N (3) A sliding window protocol using go-back-n. . . .

  27. Protocol Using Go-Back-N (4) A sliding window protocol using go-back-n. . . .

  28. Protocol Using Go-Back-N (5) A sliding window protocol using go-back-n. . . .

  29. Protocol Using Go-Back-N (6) A sliding window protocol using go-back-n. . . .

  30. Protocol Using Go-Back-N (7) A sliding window protocol using go-back-n. . . .

  31. Protocol Using Go-Back-N (8) A sliding window protocol using go-back-n. . . .

  32. Protocol Using Go-Back-N (9) A sliding window protocol using go-back-n.

  33. Protocol Using Go-Back-N (10) Simulation of multiple timers in software. • The queued timeouts • The situation after the first timeout has expired.

  34. Protocol Using Go-Back-N (11) Send window for Go-Back-N ARQ

  35. Protocol Using Go-Back-N (12) Receive window for Go-Back-N ARQ

  36. Protocol Using Go-Back-N (13) A Design of Go-Back-N ARQ

  37. Protocol Using Selective Repeat (1) A sliding window protocol using selective repeat. . . .

  38. Protocol Using Selective Repeat (2) A sliding window protocol using selective repeat. . . .

  39. Protocol Using Selective Repeat (3) A sliding window protocol using selective repeat. . . .

  40. Protocol Using Selective Repeat (4) A sliding window protocol using selective repeat. . . .

  41. Protocol Using Selective Repeat (5) A sliding window protocol using selective repeat. . . .

  42. Protocol Using Selective Repeat (6) A sliding window protocol using selective repeat. . . .

  43. Protocol Using Selective Repeat (7) A sliding window protocol using selective repeat. . . .

  44. Protocol Using Selective Repeat (8) A sliding window protocol using selective repeat. . . .

  45. Protocol Using Selective Repeat (9) A sliding window protocol using selective repeat.

  46. Protocol Using Selective Repeat (10) Send window for Selective Repeat ARQ (above) Receive window for Selective Repeat ARQ (bellow)

  47. Protocol Using Selective Repeat (11) • Initial situation with a window of size7 • After 7 frames sent and received but not acknowledged. • Initial situation with a window size of 4. • After 4 frames sent and received but not acknowledged.

  48. Example Data Link Protocols • Packet over SONET • ADSL (Asymmetric Digital Subscriber Loop)

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