The document discusses network access and connectivity. It covers physical layer protocols, network media like copper, fiber and wireless, data link layer protocols, and media access control techniques. Specific topics covered include Ethernet, Wi-Fi, physical and logical network topologies, common network cabling standards, and frame structure. The goal is for students to understand how networks are accessed at the data link layer and below.

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

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Fundamental Principles of Layer 1
Bandwidth

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Fundamental Principles of Layer 1
Throughput

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Fundamental Principles of Layer 1
Types of Physical Media

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Network Media
Copper Cabling

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Copper Cabling
Characteristics of Copper Media

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Copper Cabling
Copper Media
Shielded Twisted Pair (STP) cableUnshielded Twisted Pair (UTP) cable
Coaxial cable

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Copper Cabling
Unshielded Twisted-Pair (UTP) Cable

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Copper Cabling
Shielded Twisted-Pair (STP) Cable
Foil Shields
Braided or Foil Shield

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Copper Cabling
Coaxial Cable

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Copper Cabling
Cooper Media Safety

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UTP Cabling
Properties of UTP Cabling

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UTP Cabling
UTP Cabling Standards

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UTP Cabling
UTP Connectors

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UTP Cabling
Types of UTP Cable

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UTP Cabling
Testing UTP Cables

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UTP Cabling
Testing UTP Cables

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Fiber Optic Cabling
Properties of Fiber Optic Cabling

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Fiber Optic Cabling
Fiber Media Cable Design

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Fiber Optic Cabling
Types of Fiber Media

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Fiber Optic Cabling
Network Fiber Connectors

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Fiber Optic Cabling
Testing Fiber Cables

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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

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• 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

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Wireless Media
Wireless LAN
Cisco Linksys EA6500 802.11ac wireless router

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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

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Purpose of the Data Link Layer
The Data Link Layer

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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

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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

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Layer 2 Frame Structure
Creating a Frame

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Data Link Layer
Layer 2 Standards

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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

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Topologies
Physical and Logical Topologies

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WAN Topologies
Common Physical WAN Topologies

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WAN Topologies
Physical Point-to-Point Topology

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WAN Topologies
Logical Point-to-Point Topology

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WAN Topologies
Half and Full Duplex

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LAN Topologies
Physical LAN Topologies

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LAN Topologies
Logical Topology for Shared Media

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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

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LAN Topologies
Multi-Access Topology

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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)

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LAN Topologies
Ring Topology

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Data Link Frame
The Frame

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Data Link Frame
The Header

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Data Link Frame
Layer 2 Address

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Data Link Frame
The Trailer

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Data Link Frame
LAN and WAN Frames

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Data Link Frame
Ethernet Frame

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Data Link Frame
Point-to-Point Protocol Frame

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Data Link Frame
802.11 Wireless Frame

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Network Access
Summary
• Physical Layer Protocols
• Network Media
• Data Link Layer Protocols
• Media Access Control

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