Chapter 3 The Data Link Layer 1 Data Link Layer Design Issues - - PowerPoint PPT Presentation

▶
chapter 3
SMART_READER_LITE
LIVE PREVIEW

Chapter 3 The Data Link Layer 1 Data Link Layer Design Issues - - PowerPoint PPT Presentation

Aug 03, 2023 451 likes •932 views

Chapter 3 The Data Link Layer 1 Data Link Layer Design Issues Services Provided to the Network Layer Framing Error Control Flow Control 2 Functions of the Data Link Layer Provide service interface to the network

slide-1
SLIDE 1

The Data Link Layer

Chapter 3

1

slide-2
SLIDE 2

Data Link Layer Design Issues

  • Services Provided to the Network Layer
  • Framing
  • Error Control
  • Flow Control

2

slide-3
SLIDE 3

Functions of the Data Link Layer

  • Provide service interface to the network layer
  • Dealing with transmission errors
  • Regulating data flow
  • Slow receivers not swamped by fast senders

3

slide-4
SLIDE 4

Functions of the Data Link Layer (2)

Relationship between packets and frames.

4

slide-5
SLIDE 5

Services Provided to Network Layer

(a) Virtual communication. (b) Actual communication.

5

slide-6
SLIDE 6

Services Provided to Network Layer (2)

Placement of the data link protocol.

6

slide-7
SLIDE 7

Framing

A character stream. (a) Without errors. (b) With one error.

7

slide-8
SLIDE 8

Framing (2)

(a) A frame delimited by flag bytes. (b) Four examples of byte sequences before and after stuffing. 8

slide-9
SLIDE 9

Framing (3)

Bit stuffing (a) The original data. (b) The data as they appear on the line. (c) The data as they are stored in receiver’s memory after destuffing.

9

slide-10
SLIDE 10

Error Detection and Correction

  • Error-Correcting Codes
  • Error-Detecting Codes

10

slide-11
SLIDE 11

Error-Correcting Codes

Use of a Hamming code to correct burst errors.

11

slide-12
SLIDE 12

Error-Detecting Codes

Calculation of the polynomial code checksum.

12

slide-13
SLIDE 13

Elementary Data Link Protocols

  • An Unrestricted Simplex Protocol
  • A Simplex Stop-and-Wait Protocol
  • A Simplex Protocol for a Noisy Channel

13

slide-14
SLIDE 14

Protocol Definitions

Continued  Some definitions needed in the protocols to follow. These are located in the file protocol.h.

14

slide-15
SLIDE 15

Protocol Definitions (ctd.)

Some definitions needed in the protocols to follow. These are located in the file protocol.h.

15

slide-16
SLIDE 16

Unrestricted Simplex Protocol

16

slide-17
SLIDE 17

Simplex Stop-and- Wait Protocol

17

slide-18
SLIDE 18

A Simplex Protocol for a Noisy Channel

A positive acknowledgement with retransmission protocol.

Continued 

18

slide-19
SLIDE 19

A Simplex Protocol for a Noisy Channel (ctd.)

A positive acknowledgement with retransmission protocol.

19

slide-20
SLIDE 20

Sliding Window Protocols

  • A One-Bit Sliding Window Protocol
  • A Protocol Using Go Back N
  • A Protocol Using Selective Repeat

20

slide-21
SLIDE 21

Sliding Window Protocols (2)

A sliding window of size 1, with a 3-bit sequence number. (a) Initially. (b) After the first frame has been sent. (c) After the first frame has been received. (d) After the first acknowledgement has been received.

21

slide-22
SLIDE 22

A One-Bit Sliding Window Protocol

Continued 

22

slide-23
SLIDE 23

A One-Bit Sliding Window Protocol (ctd.)

23

slide-24
SLIDE 24

A One-Bit Sliding Window Protocol (2)

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

slide-25
SLIDE 25

A Protocol Using Go Back N

Pipelining and error recovery. Effect on an error when (a) Receiver’s window size is 1. (b) Receiver’s window size is large.

25

slide-26
SLIDE 26

Sliding Window Protocol Using Go Back N

Continued 

26

slide-27
SLIDE 27

Sliding Window Protocol Using Go Back N

Continued 

27

slide-28
SLIDE 28

Sliding Window Protocol Using Go Back N

Continued 

28

slide-29
SLIDE 29

Sliding Window Protocol Using Go Back N

29

slide-30
SLIDE 30

Sliding Window Protocol Using Go Back N (2)

Simulation of multiple timers in software.

30

slide-31
SLIDE 31

A Sliding Window Protocol Using Selective Repeat

Continued 

31

slide-32
SLIDE 32

Continued 

A Sliding Window Protocol Using Selective Repeat (2)

32

slide-33
SLIDE 33

A Sliding Window Protocol Using Selective Repeat (3)

Continued 

33

slide-34
SLIDE 34

A Sliding Window Protocol Using Selective Repeat (4)

34

slide-35
SLIDE 35

A Sliding Window Protocol Using Selective Repeat (5)

(a) Initial situation with a window size seven. (b) After seven frames sent and received, but not acknowledged. (c) Initial situation with a window size of four. (d) After four frames sent and received, but not acknowledged.

35

slide-36
SLIDE 36

Protocol Verification

  • Finite State Machined Models
  • Petri Net Models

36

slide-37
SLIDE 37

Finite State Machined Models

(a) State diagram for protocol 3. (b) Transmissions.

37

slide-38
SLIDE 38

Petri Net Models

A Petri net with two places and two transitions.

38

slide-39
SLIDE 39

Petri Net Models (2)

A Petri net model for protocol 3.

39

slide-40
SLIDE 40

Example Data Link Protocols

  • HDLC – High-Level Data Link Control
  • The Data Link Layer in the Internet

40

slide-41
SLIDE 41

High-Level Data Link Control

Frame format for bit-oriented protocols.

41

slide-42
SLIDE 42

High-Level Data Link Control (2)

Control field of (a) An information frame. (b) A supervisory frame. (c) An unnumbered frame.

42

slide-43
SLIDE 43

The Data Link Layer in the Internet

A home personal computer acting as an internet host.

43

slide-44
SLIDE 44

PPP – Point to Point Protocol

The PPP full frame format for unnumbered mode operation.

44

slide-45
SLIDE 45

PPP – Point to Point Protocol (2)

A simplified phase diagram for bring a line up and down. 45

slide-46
SLIDE 46

PPP – Point to Point Protocol (3)

The LCP frame types.

46