This document is a chapter from a Cisco networking textbook that covers network access and the physical and data link layers. It discusses various physical network media like copper, fiber optic, and wireless cables and standards. It also examines data link layer protocols, frame structure, and media access control techniques. Specific topics include Ethernet, Wi-Fi, Bluetooth standards, logical link control, MAC sublayers, and common physical WAN topologies. The objectives are to explain how the physical and data link layers support network communications and compare different media access methods.

1. © 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1
Chapter 4:
Network Access
Introduction to Networks

2. Presentation_ID 2© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 4: Objectives
Students will be able to:
 Explain how physical layer protocols and services
support communications across data networks.
 Build a simple network using the appropriate.
 Explain the role of the data link layer in supporting
communications across data networks.
 Compare media access control techniques and logical
topologies used in networks.

3. Presentation_ID 3© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 4
4.1 Physical Layer Protocols
4.2 Network Media
4.3 Data Link Layer Protocols
4.4 Media Access Control
4.5 Summary

4. Presentation_ID 4© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it Connected
Connecting to the Network

5. Presentation_ID 5© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it Connected
Connecting to the Network

6. Presentation_ID 6© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it Connected
Network Interface Cards
Connecting to the Wireless LAN with a Range Extender

7. Presentation_ID 7© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Physical Layer
The Physical Layer

8. Presentation_ID 8© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Physical Layer
Physical Layer Media

9. Presentation_ID 9© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Physical Layer
Physical Layer Standards
Standard
organization
Networking Standards
ISO
• ISO 8877: Officially adopted the RJ connectors (e.g., RJ-11, RJ-45)
• ISO 11801: Network cabling standard similar to EIA/TIA 568.
EIA/TIA
• TIA-568-C: Telecommunications cabling standards, used by nearly all
voice, video and data networks.
• TIA-569-B: Commercial Building Standards for Telecommunications
Pathways and Spaces
• TIA-598-C: Fiber optic color coding
• TIA-942: Telecommunications Infrastructure Standard for Data Centers
ANSI • 568-C: RJ-45 pinouts. Co-developed with EIA/TIA
ITU-T • G.992: ADSL
IEEE
• 802.3: Ethernet
• 802.11: Wireless LAN (WLAN) & Mesh (Wi-Fi certification)
• 802.15: Bluetooth

10. Presentation_ID 10© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Physical Layer Fundamental Principles
Media
Physical
Components
Frame Encoding
Technique
Signalling
Method
Copper
cable
• UTP
• Coaxial
• Connectors
• NICs
• Ports
• Interfaces
• Manchester Encoding
• Non-Return to Zero (NRZ)
techniques
• 4B/5B codes are used with
Multi-Level Transition Level 3
(MLT-3) signaling
• 8B/10B
• PAM5
• Changes in the
electromagnetic field
• Intensity of the
electromagnetic field
• Phase of the
electromagnetic wave
Fiber Optic
cable
• Single-mode Fiber
• Multimode Fiber
• Connectors
• NICs
• Interfaces
• Lasers and LEDs
• Photoreceptors
• Pulses of light
• Wavelength multiplexing using
different colors
• A pulse equals 1.
• No pulse is 0.
Wireless
media
• Access Points
• NICs
• Radio
• Antennae
• DSSS (direct-sequence spread-
spectrum)
• OFDM (orthogonal frequency
division multiplexing)
• Radio waves

11. Presentation_ID 11© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Bandwidth

12. Presentation_ID 12© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Throughput

13. Presentation_ID 13© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Types of Physical Media

14. Presentation_ID 14© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Network Media
Copper Cabling

15. Presentation_ID 15© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Characteristics of Copper Media

16. Presentation_ID 16© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Copper Media
Shielded Twisted Pair (STP) cableUnshielded Twisted Pair (UTP) cable
Coaxial cable

17. Presentation_ID 17© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Unshielded Twisted-Pair (UTP) Cable

18. Presentation_ID 18© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Shielded Twisted-Pair (STP) Cable
Foil Shields
Braided or Foil Shield

19. Presentation_ID 19© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Coaxial Cable

20. Presentation_ID 20© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Cooper Media Safety

21. Presentation_ID 21© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Properties of UTP Cabling

22. Presentation_ID 22© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
UTP Cabling Standards

23. Presentation_ID 23© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
UTP Connectors

24. Presentation_ID 24© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Types of UTP Cable

25. Presentation_ID 25© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Testing UTP Cables

26. Presentation_ID 26© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Testing UTP Cables

27. Presentation_ID 27© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Properties of Fiber Optic Cabling

28. Presentation_ID 28© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Fiber Media Cable Design

29. Presentation_ID 29© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Types of Fiber Media

30. Presentation_ID 30© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Network Fiber Connectors

31. Presentation_ID 31© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Testing Fiber Cables

32. Presentation_ID 32© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Fiber versus Copper
Implementation issues Copper media Fibre-optic
Bandwidth supported 10 Mbps – 10 Gbps 10 Mbps – 100 Gbps
Distance
Relatively short
(1 – 100 meters)
Relatively High
(1 – 100,000 meters)
Immunity to EMI and RFI Low
High
(Completely immune)
Immunity to electrical hazards Low
High
(Completely immune)
Media and connector costs Lowest Highest
Installation skills required Lowest Highest
Safety precautions Lowest Highest

33. Presentation_ID 33© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless Media
Properties of Wireless Media

34. Presentation_ID 34© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
• IEEE 802.11 standards
• Commonly referred to as Wi-Fi.
• Uses CSMA/CA
• Variations include:
• 802.11a: 54 Mbps, 5 GHz
• 802.11b: 11 Mbps, 2.4 GHz
• 802.11g: 54 Mbps, 2.4 GHz
• 802.11n: 600 Mbps, 2.4 and 5 GHz
• 802.11ac: 1 Gbps, 5 GHz
• 802.11ad: 7 Gbps, 2.4 GHz, 5 GHz, and 60 GHz
• IEEE 802.15 standard
• Supports speeds up to 3 Mbps
• Provides device pairing over distances from 1 to
100 meters.
• IEEE 802.16 standard
• Provides speeds up to 1 Gbps
• Uses a point-to-multipoint topology to provide
wireless broadband access.
Wireless Media
Types of Wireless Media

35. Presentation_ID 35© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless Media
Wireless LAN
Cisco Linksys EA6500 802.11ac wireless router

36. Presentation_ID 36© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless Media
802.11 Wi-Fi Standards
Standard
Maximum
Speed
Frequency
Backwards
compatible
802.11a 54 Mbps 5 GHz No
802.11b 11 Mbps 2.4 GHz No
802.11g 54 Mbps 2.4 GHz 802.11b
802.11n 600 Mbps 2.4 GHz or 5 GHz 802.11b/g
802.11ac
1.3 Gbps
(1300 Mbps)
2.4 GHz and 5.5
GHz
802.11b/g/n
802.11ad
7 Gbps
(7000 Mbps)
2.4 GHz, 5 GHz and
60 GHz
802.11b/g/n/ac

37. Presentation_ID 37© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
The Data Link Layer

38. Presentation_ID 38© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
Data Link Sublayers
Network
Data Link
LLC Sublayer
MAC Sublayer
Physical
802.3
Ethernet
802.11
Wi-Fi
802.15
Bluetooth

39. Presentation_ID 39© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
Media Access Control

40. Presentation_ID 40© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
Providing Access to Media

41. Presentation_ID 41© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Layer
Layer 2 Frame Structure

42. Presentation_ID 42© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Layer 2 Frame Structure
Creating a Frame

43. Presentation_ID 43© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Layer
Layer 2 Standards

44. Presentation_ID 44© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Layer 2 Standards
Data Link Layer Standards
Standard
organization
Networking Standards
IEEE
• 802.2: Logical Link Control (LLC)
• 802.3: Ethernet
• 802.4: Token bus
• 802.5: Token passing
• 802.11: Wireless LAN (WLAN) & Mesh (Wi-Fi certification)
• 802.15: Bluetooth
• 802.16: WiMax
ITU-T
• G.992: ADSL
• G.8100 - G.8199: MPLS over Transport aspects
• Q.921: ISDN
• Q.922: Frame Relay
ISO
• HDLC (High Level Data Link Control)
• ISO 9314: FDDI Media Access Control (MAC)
ANSI • X3T9.5 and X3T12: Fiber Distributed Data Interface (FDDI)

45. Presentation_ID 45© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Topologies
Controlling Access to the Media

46. Presentation_ID 46© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Topologies
Physical and Logical Topologies

47. Presentation_ID 47© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Common Physical WAN Topologies

48. Presentation_ID 48© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Physical Point-to-Point Topology

49. Presentation_ID 49© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Logical Point-to-Point Topology

50. Presentation_ID 50© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Half and Full Duplex

51. Presentation_ID 51© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Physical LAN Topologies

52. Presentation_ID 52© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Logical Topology for Shared Media

53. Presentation_ID 53© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Contention-Based Access
Characteristics Contention-Based Technologies
• Stations can transmit at any time
• Collision exist
• There are mechanisms to resolve
contention for the media
• CSMA/CD for 802.3 Ethernet networks
• CSMA/CA for 802.11 wireless networks

54. Presentation_ID 54© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Multi-Access Topology

55. Presentation_ID 55© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Controlled Access
Characteristics Controlled Access Technologies
• Only one station can transmit at a time
• Devices wishing to transmit must wait
their turn
• No collisions
• May use a token passing method
• Token Ring (IEEE 802.5)
• Fiber Distributed Data Interface (FDDI)

56. Presentation_ID 56© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Ring Topology

57. Presentation_ID 57© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
The Frame

58. Presentation_ID 58© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
The Header

59. Presentation_ID 59© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
Layer 2 Address

60. Presentation_ID 60© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
The Trailer

61. Presentation_ID 61© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
LAN and WAN Frames

62. Presentation_ID 62© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
Ethernet Frame

63. Presentation_ID 63© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
Point-to-Point Protocol Frame

64. Presentation_ID 64© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
802.11 Wireless Frame

65. Presentation_ID 65© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Network Access
Summary
• Physical Layer Protocols
• Network Media
• Data Link Layer Protocols
• Media Access Control

66. Presentation_ID 66© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential