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Network Guide to Networks 5th Edition

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Title: Network+ Guide to Networks 5th Edition Author: Feda Last modified by: Feda Created Date: 7/9/2007 9:56:01 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Network Guide to Networks 5th Edition


1
Network Guide to Networks 5th Edition
  • Chapter 3
  • Transmission Basics and Networking Media

2
Objectives
  • Explain basic data transmission concepts,
    including full duplexing, attenuation, latency,
    and noise
  • Describe the physical characteristics of coaxial
    cable, STP, UTP, and fiber-optic media
  • Compare the benefits and limitations of different
    networking media
  • Explain the principles behind and uses for serial
    connector cables
  • Identify wiring standards and the best practices
    for cabling buildings and work areas

3
Transmission Basics
  • Transmit
  • Issue signals along network medium
  • Transmission
  • Process of transmitting
  • Signal progress after transmitted
  • (My NIC transmitted a message and transmission
    took 10 sec to reach the server due to slow
    network)
  • Transceiver
  • Transmit and receive signals
  • NIC is a transceiver

4
Analog and Digital Signaling
  • Important data transmission characteristic
  • I) Signaling type analog or digital
  • Volt
  • Electrical current pressure
  • Electrical signal strength
  • Directly proportional to voltage
  • Signal voltage
  • Signals
  • Current, light pulses, electromagnetic waves

5
  • Analog data signals
  • Voltage varies continuously
  • Properties
  • Amplitude, frequency, wavelength, phase

6
Analog and Digital Signaling (contd.)
  • Amplitude
  • Analog waves strength
  • Frequency
  • Number of times amplitude cycles over fixed time
    period
  • Measure in hertz (Hz)
  • Wavelength
  • Distance between corresponding wave cycle points
  • Inversely proportional to frequency
  • Expressed in meters or feet

7
  • Phase
  • Waves progress over time in relationship to
    fixed point

8
Analog and Digital Signaling (contd.)
  • Analog signal benefit over digital
  • More variable
  • Convey greater subtleties with less energy
  • Drawback of analog signals
  • Varied and imprecise voltage
  • Susceptible to transmission flaws (noise)
  • Digital signals
  • Pulses of voltages
  • Positive voltage represents a 1
  • Zero voltage represents a 0

9
  • Binary system
  • 1s and 0s represent information
  • Bit (binary digit)
  • Possible values 1 or 0
  • Digital signal pulse

10
  • Byte
  • Eight bits together
  • Computers read and write information
  • Using bits and bytes
  • Find decimal value of a bit
  • Multiply the 1 or 0 by 2x (x equals bits
    position)

11
Analog and Digital Signaling (contd.)
  • Convert byte to decimal number
  • Determine value represented by each bit
  • Add values
  • Convert decimal number to a byte
  • Reverse the process
  • Convert between binary and decimal
  • By hand or calculator

12
Binary to Decimal conversion
  • Binary numbers are sometimes written prefixed
    with 0b
  • 0b0001 08 04 02 11 1
  • 0b1010 18 04 12 01 10
  • 0b1011 18 04 12 11 11

13
Decimal to Binary
  • 14 842 18 14 12 01 0b1110
  • 3 21 08 04 12 11 0b0011
  • 6 42 08 14 12 01 0b0110

14
Larger Values
  • 128 1128 064 032 016 08 04 02
    01
  • 128 0b10000000
  • 162 128 32 2
  • 162 1128 064 132 016 08 04 12
    01
  • 162 0b10100010
  • 0b1111000
  • 1128 164 132 116 08 04 02 01 0
  • 128 64 32 16 240

15
Analog and Digital Signaling (contd.)
  • Digital signal benefit over analog signal
  • More reliable
  • Less severe noise interference
  • Digital signal drawback
  • Many pulses required to transmit same information
  • Overhead
  • Nondata information
  • Required for proper signal routing and
    interpretation
  • Such as addressing information

16
Data Modulation
  • Important data transmission characteristic
  • II) Data modulation
  • Technology used to modify analog signals to make
    it suitable for carrying data over communication
    path
  • Why ?
  • Data relies on digital transmission but network
    connection (telephone lines used to connect with
    ISP) may handle only analog signals
  • Need to make signals conform to a specific
    pathway
  • Issue multiple signals to the same communication
    channel with no interference

17
Data Modulation (contd.)
  • Modem
  • Accomplishes translation
  • Converts digital to analog at the transmitting
    end
  • Converts analog to digital at the receiving end
  • Modulator/demodulator
  • Carrier wave
  • Combined with another analog signal (Information
    wave) to produce unique signal? transmitted from
    one node to another
  • Preset properties (amplitude, frequency and
    phase)
  • Purpose
  • Convey information (messenger)

18
Data Modulation (contd.)
  • Information wave (data wave)
  • Added to carrier wave
  • Modifies one carrier wave property (amplitude,
    frequency or phase)
  • Frequency modulation (FM)
  • Carrier frequency modified
  • By application of data signal
  • Amplitude modulation (AM)
  • Carrier signal amplitude modified
  • By application of data signal

19
AM and FM
20
Simplex, Half-Duplex, and Duplex
  • Important data transmission characteristic
  • III) Signal Direction direction in which the
    signals travel over the media
  • Simplex
  • Signal transmission one direction
  • Like broadcast TV
  • Half-duplex transmission
  • Signal transmission both directions but one at a
    time
  • One communication channel that maybe shared for
    multiple nodes to exchange information
  • Like walkie-talkie
  • Full-duplex (bidirectional)
  • Signals transmission both directions
    simultaneously
  • Like telephone and on data networks
  • Multiple channels on the same medium

21
  • Channel
  • Distinct communication path between nodes
  • Separated physically (wires) or logically
    (multiplexing)
  • Full duplex advantage
  • Increases speed
  • Many network devices (modems NICs) allow
    specifying half duplex or duplex

22
Multiplexing
  • Important data transmission characteristic
  • IV) Multiplexing
  • Technique that allows multiple signals to travel
    simultaneously over one medium
  • Takes place by logically separate the channel
    into subchannels
  • Subchannels
  • Logical multiple smaller channels
  • Multiplexing Devices
  • Multiplexer (mux) A device that combines many
    channel signals at the transmission end
  • Demultiplexer (demux) A device that separates
    combined signals and regenerates them at the
    receiving end

23
  • Multiplexing Types
  • TDM (time division multiplexing)
  • Divides channel into multiple time intervals
    (slots) and assigns a separate time slot for each
    node on the network to carry data from that node.
  • Inefficient when some nodes rarely send data

24
  • Statistical multiplexing
  • Transmitter assigns slots to node according to
    priority, need depending on the network
  • More efficient than TDM ? maximize available
    bandwidth

25
  • FDM (frequency division multiplexing)
  • Unique frequency band for each communications
    subchannel
  • Signals modulated with different carrier
    frequencies, then multiplexed to simultaneously
    travel over a single channel
  • FDM implemented signals of above 3400 Hz
  • Two types
  • Cellular telephone transmission
  • DSL Internet access

26
  • WDM (wavelength division multiplexing)
  • One fiber-optic connection
  • Carries multiple light signals simultaneously?20
    millions
  • DWDM (dense wavelength division multiplexing)
  • Used on most modern fiber-optic networks
  • Extraordinary capacity

27
  • Important data transmission characteristics
  • V) Relationships between nodes
  • Point-to-point transmission one transmitter and
    one receiver
  • Point-to-multipoint transmission one transmitter
    and multiple receivers
  • Broadcast transmission
  • One transmitter and multiple, undefined receivers
  • Used on wired and wireless networks
  • Simple and quick
  • TV station
  • Nonbroadcast
  • One transmitter and multiple, defined receivers

28
Relationships Between Nodes (contd.)
29
  • Important data transmission characteristics
  • V) Throughput
  • Measures amount of data transmitted during given
    time period
  • Capacity or bandwidth (technically different)
  • Quantity of bits transmitted per second (bps,
    Kbps, Mbps, Gbps, Tbps)
  • VI) Bandwidth (strict definition)
  • Measures difference between highest and lowest
    frequencies that medium can transmit
  • Range of frequencies
  • Measured in hertz (Hz)

30
Throughput
31
Baseband and Broadband
  • Baseband transmission
  • Transmission form in which digital signals sent
    through direct current (DC) pulses applied to
    wire
  • Requires exclusive use of wires capacity
  • Transmit one signal (channel) at a time
  • One node transmit at a time
  • Example Ethernet
  • Supports half-duplex mainly (nodes can
    send/receive on same wire but one at a time)
  • Broadband transmission
  • Transmission form in which signals modulated
    radiofrequency (RF) analog waves
  • Uses different frequency ranges
  • Does not encode information as digital pulses
  • Example TV cable
  • More expensive and longer

32
Transmission Flaws
  • Noise
  • Any undesirable influence degrading or distorting
    signal, measured in decibels(dB)
  • Types of noise
  • EMI (electromagnetic interference)
  • Waves emanate from electrical devices or cables
    carrying electricity.
  • EMI/RFI (radiofrequency interference)
  • Cross talk
  • When a signal traveling on one wire or cable
    infringes on the signal traveling on adjacent
    wire or cable
  • NEXT (near end cross talk)
  • Potential cause improper termination (damage
    wire insulation, untwisted wire)
  • Environmental influences
  • Heat

33
Transmission Flaws (contd.)
34
Transmission Flaws (contd.)
  • Attenuation
  • Loss of signals strength as it travels away from
    source
  • Signal boosting technology
  • Analog signals pass through amplifier (device
    increases voltage of a signal)
  • Noise also amplified
  • Regeneration
  • Digital signals retransmitted in original form
  • Repeater device regenerating digital signals
  • Amplifiers and repeaters
  • OSI model Physical layer
  • Extend length of network

35
Transmission Flaws (contd.)
  • Latency
  • Delay between signal transmission and receipt
  • Causes
  • Cable length
  • Intervening connectivity device
  • RTT (round trip time)
  • Time for packet to go from sender to receiver,
    then back from receiver to sender
  • Measured in milliseconds
  • May cause network transmission errors

36
Common Media Characteristics
  • Selecting transmission media
  • Match networking needs with media characteristics
  • Physical media characteristics
  • Throughput
  • Cost
  • Size and scalability
  • Connectors
  • Noise immunity

37
Throughput
  • Most significant transmission method factor
  • Measures amount of data transmitted during given
    time period
  • Causes of limitations
  • Laws of physics (not faster than light)
  • Signaling and multiplexing techniques
  • Noise (more time and resources to compensate for
    noise)
  • Devices connected to transmission medium
  • Fiber-optic cables allows faster throughput
  • Compared to copper or wireless connections

38
Cost
  • Precise costs difficult to pinpoint
  • Media cost dependencies
  • Existing hardware, network size, labor costs
  • Variables influencing final cost
  • Installation cost
  • New infrastructure cost versus reuse
  • Maintenance and support costs
  • Cost of lower transmission rate affecting
    productivity
  • Cost of obsolescence

39
Noise Immunity
  • Noise distorts data signals
  • Distortion rate dependent upon transmission media
  • Fiber-optic least susceptible to noise ? it does
    not use electric current, but light waves, to
    conduct signals
  • Limit impact on network
  • Cable installation
  • Far away from powerful electromagnetic forces
  • Select media protecting signal from noise (cables
    )
  • Antinoise algorithms (pipelines)

40
Size and Scalability
  • Three specifications
  • Maximum nodes per segment
  • Maximum segment length
  • Maximum network length
  • Depends on physical characteristics of wires and
    electrical characteristics of data transmission
  • Maximum nodes per segment dependency
  • Attenuation and latency
  • Maximum segment length dependency
  • Attenuation and latency plus segment type
  • Maximum distance a signal can travel and still be
    interpreted accurately

41
Size and Scalability (contd.)
  • Segment types
  • Populated contains end nodes
  • Unpopulated(Link segment) No end nodes (routers)
  • Segment length limitation
  • After certain distance, signal loses strength
  • Cannot be accurately interpreted
  • Maximum network length dependency
  • Attenuation and latency plus segment type
  • Sum of the networks segment length

42
Connectors and Media Converters
  • Connectors
  • Hardware connecting wire to network device
  • Specific to particular media type
  • Affect costs
  • Installing and maintaining network
  • Ease of adding new segments or nodes
  • Technical expertise required to maintain network
  • Media converter
  • Hardware enabling networks or segments running on
    different media to interconnect and exchange
    signals

43
Connectors and Media Converters (contd.)
44
Coaxial Cable
  • Foundation for Ethernet network
  • Central metal core (often copper)
  • Surrounded by insulator, braided metal shielding
    (braiding or shield) and an outer cover (sheath
    or jacket)

45
Coaxial Cable
  • Central metal core
  • Carries electromagnetic signal
  • Insulator
  • Plastic material such as Polyvinyl Chloride (PVC)
    or Teflon to protect the core from the metal
    shield (avoid short circuit)
  • Braided metal shielding
  • Shield (noise) and ground for signal
  • Sheath or jacket
  • Made of PVC or fire-resistance plastic
  • Protects against physical damage

46
Coaxial Cable (contd.)
  • High noise resistance
  • Advantage over twisted pair cabling
  • Carry signals farther before amplifier required
  • Disadvantage over twisted pair cabling
  • More expensive? more raw manufacture materials
  • Hundreds of specifications
  • RG (Radio Guide) specification number
  • Differences shielding and conducting cores
  • Transmission characteristics(impedance,
    attenuation, throuhput)

47
Coaxial Cable (contd.)
  • Conducting core
  • American Wire Gauge (AWG) size
  • Larger AWG ?smaller diameter
  • Data networks usage
  • RG-6 Used in modern cable TV connections, most
    common
  • RG-8 Thicknet--obsolete
  • RG-58 Thinnetalso obsolete for data networks
  • RG-59 Used for short spans in modern cable TV
    connections

48
Coaxial Cable (contd.)
  • Connectors
  • F-type
  • BNC

49
Coaxial Cable (contd.)
50
Twisted Pair Cable
  • Most common today
  • Color-coded insulated copper wire pairs
  • 0.4 to 0.8 mm diameter
  • Every two wires twisted around each other
  • All pairs encased in a plastic sheath
  • Pair numbers depend on the cable type

51
Twisted Pair Cable (contd.)
  • Twist ratio
  • Number of twists per meter or foot
  • High twist ratio
  • Greater attenuation (longer cable)
  • More resistance to cross talk
  • Higher-quality
  • More expensive

52
Twisted Pair Cable (contd.)
  • Different designs ? environments purposes
  • Dependencies
  • Twist ratio, number of wire pairs, copper grade,
    shielding type, shielding materials
  • 1 to 4200 wire pairs possible
  • Wiring standard specification
  • TIA/EIA 568
  • Twisted pair wiring types
  • Cat (category) 3, 4, 5, 5e, 6, and 6e, Cat 7
  • CAT 5 most often used in modern LANs

53
Twisted Pair Cable (contd.)
  • Advantages
  • Relatively inexpensive
  • Flexible
  • Easy installation
  • Spans significant distance before requiring
    repeater (not as far as coax)
  • Accommodates several different topologies (star
    star-hybrid
  • Handles current faster networking transmission
    rates
  • Two categories
  • STP (shielded twisted pair)
  • UTP (unshielded twisted pair)

54
STP (Shielded Twisted Pair)
  • Individually insulated
  • Surrounded by metallic substance shielding (foil)
  • Barrier to external electromagnetic forces
  • Contains electrical energy of signals inside
  • May be grounded to enhance its protective effects
  • Effectiveness of the shield depends on noise
    level and type, thickness and material type,
    symmetry and consistency and grounding mechanism

55
UTP (Unshielded Twisted Pair)
  • One or more insulated wire pairs
  • Encased in plastic sheath
  • No additional shielding
  • Less expensive, less noise resistance

56
UTP (Unshielded Twisted Pair) (contd.)
  • EIA/TIA standards
  • Cat 3 (Category 3)up to 10 Mbps
  • Cat 4 (Category 4)up to 16 Mbps
  • Cat 5 (Category 5)up to 1000 Mbps
  • Cat 5e (Enhanced Category 5) higher twist ratio
  • Cat 6 (Category 6) six times the throughput of
    Cat 5
  • Cat 6e (Enhanced Category 6)
  • Cat 7 (Category 7) signal rate up to 1G

57
UTP (Unshielded Twisted Pair) (contd.)
58
Comparing STP and UTP
  • Throughput
  • STP and UTP transmit the same rates depending on
    the cabling grade and transmission method
    (10Mbps-10Gbps)
  • Cost
  • STP and UTP vary depending on the copper grade,
    category rating and any enhancement
  • Typically STP is more expensive (more material,
    grounding)
  • Noise immunity
  • STP more noise resistant because of the shield
  • UTP subject to techniques to offset noise
    (filtering balancing)

59
Comparing STP and UTP (contd.)
  • Size and scalability
  • STP and UTP maximum segment length
  • 100 meters (1024 nodes)
  • Connector
  • STP and UTP use RJ-45 (Registered Jack 45)
  • Telephone connections use RJ-11 (Registered Jack
    11)

60
Terminating Twisted Pair Cable
  • Patch cable
  • Relatively short cable (3-25 ft.)
  • Connectors at both ends
  • Proper cable termination techniques
  • Basic requirement for two nodes to communicate
  • Poor terminations
  • Lead to loss or noise ?signal error
  • TIA/EIA standards for inserting connectors
    (RJ-45)
  • TIA/EIA 568A
  • TIA/EIA 568B
  • Functionally similar
  • One type of standard for every RJ-45 plugs and
    jacks on the network

61
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62
  • Straight-through cable
  • Terminate RJ-45 plugs at both ends identically
  • Workstation-hub or router
  • Crossover cable
  • Transmit and receive wires on one end reversed
  • Workstation-workstation or hub-hub
  • Pairs 2 3 are reversed (receive and send data)

63
Terminating Twisted Pair Cable (contd.)
  • Termination tools
  • Wire cutter
  • Wire stripper
  • Crimping tool

64
Terminating Twisted Pair Cable (contd.)
  • After making cables
  • Verify data transmit and receive

65
Fiber-Optic Cable
  • Fiber-optic cable (fiber)
  • One (or several) glass or plastic fibers at its
    center (core)
  • Data transmission
  • Pulsing light sent from laser (1 and 10Gb
    technology) or LED (light-emitting diode) through
    central fibers
  • Cladding
  • Layer of glass or plastic surrounding fibers
  • Different density from glass or plastic in
    strands
  • Reflects light back to core
  • Allows fiber to bend

66
Fiber-Optic Cable (contd.)
  • Plastic buffer
  • Outside cladding
  • Protects cladding and core
  • Opaque
  • Absorbs any escaping light
  • Kevlar strands (polymeric fiber) surround plastic
    buffer
  • Plastic sheath covers Kevlar strands

67
  • Different varieties
  • Based on intended use and manufacturer
  • Two categories
  • Single-mode
  • Multimode

68
SMF (Single-Mode Fiber)
  • Uses narrow core (lt 10 microns in diameter)
  • Laser generated light travels over one path
  • Little reflection
  • Light does not disperse
  • Accommodates
  • Highest bandwidths, longest distances
  • Connects carriers two facilities
  • Costs prohibit typical LANs, WANs use

69
SMF (Single-Mode Fiber) (contd.)
70
MMF (Multimode Fiber)
  • Uses core with larger diameter than single-mode
    fiber
  • Common size 62.5 microns
  • Laser or LED generated light pulses travel at
    different angles
  • Common uses
  • Cables connecting router to a switch
  • Cables connecting server on network backbone

71
MMF (Multimode Fiber) (contd.)
72
MMF (Multimode Fiber) (contd.)
  • Benefits
  • Extremely high throughput
  • Very high resistance to noise
  • Excellent security
  • Ability to carry signals for much longer
    distances before requiring repeaters than copper
    cable
  • Industry standard for high-speed networking
  • Drawback
  • More expensive than twisted pair cable
  • Requires special equipment to splice
  • Difficult repair

73
MMF (Multimode Fiber) (contd.)
  • Characteristics of Fibers
  • Throughput
  • Reliable transmission rates
  • Can reach 100 gigabits (or 100,000 megabits) per
    second per channel (but only for singlemode, not
    multimode)
  • Cost
  • Most expensive transmission medium, NICs, hubs
    and labors
  • Connectors
  • ST (straight tip)
  • SC (subscriber connector or standard connector)
  • LC (local connector)
  • MT-RJ (mechanical transfer registered jack)

74
MMF (Multimode Fiber) (contd.)
  • Noise immunity
  • Unaffected by EMI
  • Size and scalability
  • Segment lengths vary
  • 150 to 40,000 meters
  • Due primarily to optical loss

75
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76
DTE (Data Terminal Equipment) and DCE (Data
Circuit-Terminating Equipment) Connector Cables
  • DTE (data terminal equipment)
  • Any end-user device
  • DCE (data circuit-terminating equipment)
  • Device that processes signals
  • Supplies synchronization clock signal

77
DTE and DCE Connector Cables (contd.)
  • DTE and DCE connections
  • Serial
  • Pulses flow along single transmission line
  • Sequentially
  • Serial cable
  • Carries serial transmissions

78
DTE and DCE Connector Cables (contd.)
79
DTE and DCE Connector Cables (contd.)
  • RS-232 (Recommended Standard 232)
  • EIA/TIA standard
  • Physical layer specification
  • Signal voltage, timing, compatible interface
    characteristics
  • Connector types
  • RJ-45 connectors, DB-9 connectors, DB-25
    connectors
  • RS-232 used between PC and router today
  • RS-232 connections
  • Straight-through, crossover, rollover

80
Structured Cabling
  • Cable plant
  • Hardware making up enterprise-wide cabling system
  • Standard
  • TIA/EIA joint 568 Commercial Building Wiring
    Standard

81
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82
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83
Structured Cabling (contd.)
  • Components
  • Entrance facilities
  • MDF (main distribution frame)
  • Cross-connect facilities
  • IDF (intermediate distribution frame)
  • Backbone wiring
  • Telecommunications closet
  • Horizontal wiring
  • Work area

84
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85
Structured Cabling (contd.)
86
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87
Best Practices for Cable Installation and
Management
  • Choosing correct cabling
  • Follow manufacturers installation guidelines
  • Follow TIA/EIA standards
  • Network problems
  • Often traced to poor cable installation
    techniques
  • Installation tips to prevent Physical layer
    failures
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