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Presentation_ID 1© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 4: Network Access
Presentation_ID 2© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
4.1 Physical Layer Protocols
Presentation_ID 3© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it Connected
Connecting to the Network
Presentation_ID 4© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it Connected
Connecting to the Network (cont.)
Presentation_ID 5© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Getting it Connected
Network Interface Cards
Connecting to the Wireless LAN with a Range Extender
Presentation_ID 6© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Physical Layer
The Physical Layer
Presentation_ID 7© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Physical Layer
Physical Layer Media
Presentation_ID 8© 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
Presentation_ID 9© 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
Presentation_ID 10© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Bandwidth
Presentation_ID 11© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Throughput
Presentation_ID 12© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fundamental Principles of Layer 1
Types of Physical Media
Gigabit Ethernet Interfaces
SHDSLInterface
ManagementPorts
FastEthernet Switch Ports
USB Mini-BConnector
USB Type A Connector
Presentation_ID 13© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
4.2 Network Media
Presentation_ID 14© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Characteristics of Copper Media
Presentation_ID 15© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Copper Media
Shielded Twisted Pair (STP) Cable
Unshielded Twisted Pair (UTP) Cable
Coaxial Cable
Presentation_ID 16© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
UTP Cable
Presentation_ID 17© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
STP Cable
Foil Shields
Braided or Foil Shield
Presentation_ID 18© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Coaxial Cable
Presentation_ID 19© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Copper Cabling
Cooper Media Safety
Presentation_ID 20© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Properties of UTP CablingUTP cable does not use shielding to counter the effects of EMI and RFI. Instead, cable designers have discovered that they can limit the negative effect of crosstalk by:
Cancellation
Varying the number of twists per wire pair
Presentation_ID 21© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
UTP Cabling Standards
Presentation_ID 22© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
UTP Connectors
Presentation_ID 23© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Types of UTP Cable
Presentation_ID 24© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
UTP Cabling
Testing UTP CablesAfter installation, a UTP cable tester should be used to test for the following parameters:
Wire map
Cable length
Signal loss due to attenuation
Crosstalk
Presentation_ID 25© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Properties of Fiber Optic CablingFiber-optic cabling is now being used in four types of industry:
Enterprise Networks
Fiber-to-the-home (FTTH) and Access Networks
Long-Haul Networks
Submarine Networks
Presentation_ID 26© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Fiber Media Cable Design
Presentation_ID 27© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Types of Fiber Media
Presentation_ID 28© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Network Fiber Connectors
Presentation_ID 29© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Fiber Optic Cabling
Testing Fiber Cables
Presentation_ID 30© 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 LowHigh
(Completely immune)
Immunity To Electrical Hazards LowHigh
(Completely immune)
Media And Connector Costs Lowest Highest
Installation Skills Required Lowest Highest
Safety Precautions Lowest Highest
Presentation_ID 31© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless Media
Properties of Wireless MediaWireless does have some areas of concern including:
Coverage area
Interference
Security
Presentation_ID 32© 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 Mb/s• 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
Presentation_ID 33© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless Media
Wireless LAN
Cisco Linksys EA6500 802.11ac Wireless Router
Presentation_ID 34© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Wireless Media
802.11 Wi-Fi Standards
StandardMaximum
SpeedFrequency
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
Presentation_ID 35© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
4.3 Data Link Layer Protocols
Presentation_ID 36© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
The Data Link Layer
Presentation_ID 37© 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 E
ther
net
802.
11 W
i-Fi
802.
15 B
luet
ooth
Presentation_ID 38© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
Media Access ControlThe Data Link Layer
Presentation_ID 39© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Purpose of the Data Link Layer
Providing Access to Media
Presentation_ID 40© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Layer
Formatting Data for Transmission
Presentation_ID 41© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Layer 2 Frame Structure
Creating a Frame
Presentation_ID 42© 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)
Presentation_ID 43© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Topologies
Controlling Access to the Media
Presentation_ID 44© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Topologies
Physical and Logical Topologies
Presentation_ID 45© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Topologies
Physical and Logical Topologies (cont.)
Presentation_ID 46© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Common Physical WAN Topologies
Presentation_ID 47© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Physical Point-to-Point Topology
Presentation_ID 48© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Logical Point-to-Point Topology
Presentation_ID 49© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
WAN Topologies
Half- and Full-Duplex
Half-Duplex
Full-Duplex
Presentation_ID 50© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Physical LAN Topologies
Presentation_ID 51© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Logical Topology for Shared Media
Presentation_ID 52© 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
Presentation_ID 53© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Multi-Access Topology
Presentation_ID 54© 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 wanting to transmit must wait
their turn• No collisions• May use a token passing method
• Token Ring (IEEE 802.5)• FDDI
Presentation_ID 55© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
LAN Topologies
Ring Topology
Presentation_ID 56© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
The Frame
Presentation_ID 57© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
The Header
Presentation_ID 58© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
Layer 2 Address
Presentation_ID 59© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
The Trailer
Presentation_ID 60© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
LAN and WAN Frames
Presentation_ID 61© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
Ethernet Frame
Presentation_ID 62© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
Point-to-Point Protocol Frame
Presentation_ID 63© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
802.11 Wireless Frame
Presentation_ID 64© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Data Link Frame
802.11 Wireless FrameProtocol Version field: Version of 802.11 frame in useType and Subtype fields: Identifies one of three functions and sub functions of the frame: control, data, and managementTo DS field: Set to 1 in data frames destined for the distribution system (devices in the wireless structure)From DS field: Set to 1 in data frames exiting the distribution systemMore Fragments field: Set to 1 for frames that have another fragment Retry field: Set to 1 if the frame is a retransmission of an earlier framePower Management field: Set to 1 to indicate that a node will be in power-save modeMore Data field: Set to 1 to indicate to a node in power-save mode that more frames are buffered for that nodeWired Equivalent Privacy (WEP) field: Set to 1 if the frame contains WEP encrypted information for securityOrder field: Set to 1 in a data type frame that uses Strictly Ordered service class (does not need reordering)Duration/ID field: Depending on the type of frame, represents either the time, in microseconds, required to transmit the frame or an association identity (AID) for the station that transmitted the frameDestination Address (DA) field: MAC address of the final destination node in the networkSource Address (SA) field: MAC address of the node that initiated the frameReceiver Address (RA) field: MAC address that identifies the wireless device that is the immediate recipient of the frameFragment Number field: Indicates the number for each fragment of a frameSequence Number field: Indicates the sequence number assigned to the frame; retransmitted frames are identified by duplicate sequence numbersTransmitter Address (TA) field: MAC address that identifies the wireless device that transmitted the frameFrame Body field: Contains the information being transported; for data frames, typically an IP packetFCS field: Contains a 32-bit cyclic redundancy check (CRC) of the frame