chapter 4: network access
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Chapter 4: Network Access. Introduction to Networks. 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. - PowerPoint PPT PresentationTRANSCRIPT
© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1
Chapter 4:Network Access
Introduction to Networks
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.
Presentation_ID 3© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 44.1 Physical Layer Protocols4.2 Network Media4.3 Data Link Layer Protocols4.4 Media Access Control4.5 Summary
Presentation_ID 4© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it ConnectedConnecting to the Network
Presentation_ID 5© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it ConnectedConnecting to the Network
Presentation_ID 6© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it ConnectedNetwork Interface Cards
Connecting to the Wireless LAN with a Range Extender
Presentation_ID 7© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Physical LayerThe Physical Layer
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Purpose of the Physical LayerPhysical Layer Media
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Purpose of the Physical LayerPhysical 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
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Fundamental Principles of Layer 1Physical 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 1Bandwidth
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Fundamental Principles of Layer 1Throughput
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Fundamental Principles of Layer 1Types of Physical Media
Presentation_ID 14© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Network MediaCopper Cabling
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Copper CablingCharacteristics of Copper Media
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Copper CablingCopper Media
Shielded Twisted Pair (STP) cableUnshielded Twisted Pair (UTP) cable
Coaxial cable
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Copper CablingUnshielded Twisted-Pair (UTP) Cable
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Copper CablingShielded Twisted-Pair (STP) Cable
Foil Shields
Braided or Foil Shield
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Copper CablingCoaxial Cable
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Copper CablingCooper Media Safety
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UTP CablingProperties of UTP Cabling
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UTP CablingUTP Cabling Standards
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UTP CablingUTP Connectors
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UTP CablingTypes of UTP Cable
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UTP CablingTesting UTP Cables
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UTP CablingTesting UTP Cables
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Fiber Optic CablingProperties of Fiber Optic Cabling
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Fiber Optic CablingFiber Media Cable Design
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Fiber Optic CablingTypes of Fiber Media
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Fiber Optic CablingNetwork Fiber Connectors
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Fiber Optic CablingTesting Fiber Cables
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Fiber Optic CablingFiber 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
Presentation_ID 33© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless MediaProperties 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 MediaTypes of Wireless Media
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Wireless MediaWireless LAN
Cisco Linksys EA6500 802.11ac wireless router
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Wireless Media802.11 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 LayerThe Data Link Layer
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Purpose of the Data Link LayerData Link Sublayers
Network
Data Link
LLC Sublayer
MAC Sublayer
Physical
802.
3 E
ther
net
802.
11 W
i-Fi
802.
15 B
luet
ooth
Presentation_ID 39© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link LayerMedia Access Control
Presentation_ID 40© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link LayerProviding Access to Media
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Data Link LayerLayer 2 Frame Structure
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Layer 2 Frame StructureCreating a Frame
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Data Link LayerLayer 2 Standards
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Layer 2 StandardsData 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)
Presentation_ID 45© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
TopologiesControlling Access to the Media
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TopologiesPhysical and Logical Topologies
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WAN TopologiesCommon Physical WAN Topologies
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WAN TopologiesPhysical Point-to-Point Topology
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WAN TopologiesLogical Point-to-Point Topology
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WAN TopologiesHalf and Full Duplex
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LAN TopologiesPhysical LAN Topologies
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LAN TopologiesLogical Topology for Shared Media
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LAN TopologiesContention-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
Presentation_ID 54© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN TopologiesMulti-Access Topology
Presentation_ID 55© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN TopologiesControlled 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)
Presentation_ID 56© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN TopologiesRing Topology
Presentation_ID 57© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link FrameThe Frame
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Data Link FrameThe Header
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Data Link FrameLayer 2 Address
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Data Link FrameThe Trailer
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Data Link FrameLAN and WAN Frames
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Data Link FrameEthernet Frame
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Data Link FramePoint-to-Point Protocol Frame
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Data Link Frame802.11 Wireless Frame
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Network AccessSummary• Physical Layer Protocols
• Network Media
• Data Link Layer Protocols
• Media Access Control
Presentation_ID 66© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential