Data Communication & Networking CSCI Dr. Thomas Hicks Computer Science Department Trinity University 1

Transcription

1 Data Communication & Networking CSCI 3342 Dr. Thomas Hicks Computer Science Department Trinity University 1 1

2 Must Consider Protocols 2

3 Protocols

4 Guided & Unguided Media 4

5 Guided & Unguided Transmission Media 5

6 Guided & Unguided Host-To-Network Layer Also Called Link Layer 6

7 Computers Use Electromagnetic Signals To Represent Data Signals Are Transmitted In The Form Of Electromagnetic Energy! Electromagnetic Signals Can Travel Through A Vacuum, Air, Metals, Glass, Fiber, Plastic, Water, & Other Transmission Media. 7

8 Electromagnetic Energy 8

9 Electromagnetic Energy Electromagnetic Energy = + Electrical Fields Magnetic Fields Vibrating In Relation To Each Other Power Voice Radio Waves Infrared Light Visible Light Ultraviolet Light X Rays Gamma Rays Cosmic Rays 9

10 Electromagnetic Spectrum - 1 Power Voice Radio Waves Infrared Light Visible Light Ultraviolet Light X Rays Gamma Rays Cosmic Rays Each Of These Forms Of Electromagnetic Energy Has It s Place In The Electromagnetic Spectrum. Where Is Ethernet In This Spectrum? 10

11 Electromagnetic Spectrum - 2 Not All Portions Of The Spectrum Have Been Harnessed For Data Communications. Voice-band Frequencies Most Often Use? Metal Cables Radio Frequencies Use? Air Visible Light Frequencies Use? Fiber Optic 11

12 Straight Wiring vs Twisted Pair 12

13 In The Beginning- Flat Parallel Cable Early Communication Was Done With Two Flat Parallel Lines Generally Encased In Plastic Insulation Similar To The Electrical Lines In Your Homes. Lots Of Noise Limited Distance! Not On The List In The Previous Slide! Not Used Today! 13

14 Unshielded Twisted-Pair Cable UTP 2 Medal Conductors Usually Copper Colored Plastic Outer Insulation Most Common Type Of Telecommunication Medium Used Today 14

15 Shielded Twisted-Pair Cable STP 15

16 16

17 Same 16 Units Of Noise On Top Wire & 12 On Bottom Wire 17

18 Twisted-Pair Frequency Range Human Voice Has Frequency Range of 0 to 4 KHz. Sampling Rate = 2 * Highest Frequency (4000 Hz) Works Fine For Voice! Phone Company Has Used It For Years! Several Grades/Thicknesses 18

19 Shielded Foil Twisted-Pair (SFTP) Metal Shield Helps Prevent Noise Metal Shield Helps Avoid Cross-Talk The Undesired Effect Of One Channel On Another 19

20 Twisted Pairs Often Bundled! 20

21 UTP Gage Makes Is The Difference! UTP Performance 21

22 Wiring Categories 22

23 EIA Grading - UTP Electronic Industries Association Category 1 Category 2 Category 3 Category 4 Category 5 POTS Analog Voice, ISDN Interface Door Bell Not For Data IBM Token Ring Some Analog Voice Data <= 4 Mbps Voice/Data 10Base-T Data <= 16 Mbps 16 Mbps Token Ring Data <= 20 Mbps 100Base-T Ethernet 155 Mbps ATM 1Gbps [4 pair] 23

24 EIA Grading For UTP (cont) Category 5e (enhanced) Data <= 200 Mbps for 100 Meters 155 Mbps ATM Gigabit Ethernet [GE] Category 6 Shielded Foil Twisted-Pair (SFTP) Super-fast broadband applications 100BaseT, ATM & GE Signal Rate Up To 200 MHz [4 Pairs] Category 7 Gigabit Ethernet [GE] at 100 Meters Super-fast broadband applications Signal Rate Up To 600 MHz [4 Pairs] The Twist" isn't dead. In fact, the music keeps getting faster. 24

25 Categories of unshielded twisted-pair cables Category Bandwidth Data Rate Digital/Analog Use 1 very low < 100 kbps Analog Telephone 2 < 2 MHz 2 Mbps Analog/digital T-1 lines 3 16 MHz 10 Mbps Digital LANs 4 20 MHz 20 Mbps Digital LANs MHz 100 Mbps Digital LANs MHz 200 Mbps Digital LANs MHz 600 Mbps Digital LANs 25

26 Prices Continue To Change 26

27 Unshielded Twisted-Pair 1000 ft Cable Costs $69.99 UTP Look Up 1000' Cat 6? 27

28 Internet Pricing Varies Cat 6- Complete Cables 28

29 UTP Cable With Boot 29

30 2014? Price Changes? Cat

31 2014? Price Changes? Cat

32 Cat 5-6 Standards 32

33 UTP Ethernet Connections Generally 8 Pin Cat 5 33

34 Ethernet Cables 568A 34

35 Tools 35

36 Name The Tool! 36

37 Name The Tool! 37

38 Name The Tool! 38

39 Name The Tool! 39

40 Name The Tool! 40

41 Name The Tool! 41

42 Name The Tool! yahoo.net/cateforrjrjr.html 42

43 Name The Tool! 43

44 Name The Tool! 44

45 Name The Tool! 45

46 Coax 46

47 Metal Mesh Coaxial Cable - coax Usually Copper 47

48 Coax Signal - RG Ratings Coaxial Wire Categorized By Radio Government Ratings Each Different Specs/Thicknesses etc. RG-8 Thick Ethernet RG-9 Thick Ethernet RG-11 Thick Ethernet RG-58 Thin Ethernet RG-59 TV 48

49 Coax Signal - RG Ratings Coax Carries Signals Of Higher Frequencies Than Twisted Pair 49

50 Categories Of Coaxial Cable Category Impedance Use RG W Cable TV RG W Thin Ethernet RG W Thick Ethernet 50

51 Coaxial Performance 51

52 BNC 52

53 BNC Connectors 53

54 Connectors 54

55 Coax Connectors There Area A Variety Of Coax Connectors 55

56 Fiber Optic 56

57 Fiber Optic Construction 57

58 Fiber Optic Cable Single Strand 58

59 Fiber Optic Cable - Multi Strand Made of Glass Or Plastic Transmit Light Signals # Fibers Vary Often More Than One In The Cable 59

60 Optical Fiber Cables 60

61 Optical Fiber Cables There Are Many Ways To Connect Cables 61

62 There Are Many Different Connector Types Fiber Optic Connectors 62

63 Fiber Optic Connectors 63

64 Fiber Optic Connectors Connectors Must Be As Precise As The Cable Itself. Metal Connectors Provide A Greater Degree Of Latitude With Respect To Length. Fiber Connectors Must Be Ultra Precise. If Connectors Overly Tight Alter Angle Reflection. If Connectors Have A Gap Dissipate Signal. 64

65 About Fiber Optic Communication 65

66 Light - 1 Light Travels 186,000 Miles/Second In A Vacuum. The Speed Of Light Varies With The Density Of The Medium. Light Travels In A Straight Line As Long As It Is Moving Through A Single Substance. 66

67 Light - 2 Assume That A Ray Of Light Travel From Air [Less Dense] Into A Water [More Dense] The Speed Changes Abruptly. Refraction - The Change In The Light Angle 67

68 Light - 3 Refraction - The Change In The Light Angle A Beam Traveling From Less Dense Into More Dense Is Bent Toward The Vertical Axis. Vertical Axis Angle Of Incidence Angle Of Refraction AI > AR 68

69 Light 4 Angles Of Incidence/Refraction Refraction - The Change In The Light Angle A Beam Traveling From More Dense Into Less Dense Is Bent Away From The Vertical Axis. Vertical Axis Angle Of Refraction Angle Of Incidence AR > AI 69

70 Light 5 Critical Angle At Some Point The Change In The Incidence Angle Results In A Refracted Angle Of 90 Degrees. This Is Called The Critical Angle. 70

71 Light 6 Angle Of Reflection When The Angle Of Incidence Is Greater Than The Critical Angle, A Reflection Occurs. Light No Longer Passes Into The Less Dense Medium 71

72 Why Fiber? Use A Glass Rod? We could transmit through a high quality glass rod Why Use Fiber Optic Cable? Doesn t bend very well. Easily broken.. 72

73 Optical Fibers Use Reflection To Guide Light Through A Channel. Light 7 73

74 Fiber Optic Communication An Optical Fiber is a waveguide for light that consists of : Core : inner part where wave propagates Cladding: outer part used to keep wave in core Buffer: protective coating Jacket: outer protective shield 74

75 Fiber Optic Communication The Glass/Plastic Core Is Surrounded By Less Dense Glass/Plastic Cladding. The Idea Is For The Light To Reflect Off The Cladding & Remain In The Fiber Channel. Information Is Encoded On The Beam Of Light As A Series Of On-Off Flashes That Represent 0 s & 1 s. 75

76 Fiber Optic Communication (cont) Core Must Be Ultra-pure And Completely Regular In Shape & Size. Chemical Differences & Irregularities Ruin Reflections. Outer Jacket Teflon, Plastic, Metal Tubing, Metal Mesh, etc. Pros & Cons In Strength vs. Installation Ease. 76

77 Fiber Types 77

78 Fiber Type Sample Fiber Types Core (microns) Cladding (microns) 62.5/ / / /

79 Fiber Types Type Core Cladding Mode 50/ Multimode, graded-index 62.5/ Multimode, graded-index 100/ Multimode, graded-index 7/ Single-mode 79

80 Optical Fiber Performance 80

81 How Light Travels Through Fiber Propagation Modes 81

82 How Light Propagates/Travels Through Fiber 82

83 About Multimode Step-Index Fiber Step-Index Fibers obtain their name from this abrupt change, called the step change, in refractive index. In Step-Index Multimode Fiber, Light Travels In A Straight Line Until It Reaches The Interface Of The Core & The Cladding. Then It Changes Abruptly. Unfortunately Some Of The Beams Strike The Interface At An Angle Smaller Than The Critical Angle & Are Lost. This makes Multimode Fiber Inadequate For Precise Applications! Since Some Bounce More Than Others, The Sequence Changes And Must Be Recombined! 83

84 About Multimode Graded-Index Fiber In graded-index fibers, the refractive index of the core varies gradually as a function of radial distance from the fiber center. Index Refers To Index Of Refraction. Graded Fiber Refers To A Difference In Grades. Density Highest At Core. Density Lowest At Interface. A Horizontal Beam Straight Through The Core Would Be The Only Straight Line. Requires Careful Placement Of Receiver To Reconstruct Signals Accurately. The performance of multimode graded-index fibers is usually superior to multimode step-index fibers. 84

85 About Single Mode Fiber Graded Fiber Refers To A Difference In Grades. Density Highest At Core. Density Lowest At Interface. Is Less Dense Than Multimode! Highly Focused Beam Of Light Limit Beams To Small Range Of Angles All Close To Horizontal! Beams Do Not Have To Be Recombined! 85

86 Light Sources For Fiber Optic The Fiber Optic Receiving Device Must Have A Photosensitive Cell Called A Photodiode. The Fiber Optic Light Source Can Be Light-Emitting Diode (LED) Or An Injection Laser. LED s -Cheaper Unfocused Laser More Expensive Highly Focused 86

87 Fiber Pros & Cons 87

88 Advantages Of Fiber Optic Less Noise. Noise Is Not A Factor In Light. External Light Only Possible Interference This Blocked By Outer Jacket. Less Signal Attenuation Greater Distance Miles Without Regeneration. Much Higher Bandwidth 88

89 Disadvantages Of Fiber Optic Much More Expensive Materials Instillation, etc. Laser Light Source Can Cost Thousands Of Dollars Installation Requires Much More Training & Equipment Fragile - Glass Is More Easily Broken Than Wire. 89

90 Transmission 90

91 2 Classes Of Transmission Media Guilded Media Unguilded Media Twisted Pair Cable Coaxial Cable Fiber-Optic Cable 91

92 92

93 Radio Wave 93

94 Unguilded Media 94

95 95

96 Troposphere The Portion Of The Earth s Atmosphere Extending Out About 30 Miles What We Think Of As Air Troposphere Where Clouds, Wind, Weather Appear Jet Travel Ionosphere Ionosphere The Portion Between The Troposphere And Outer Space. Contains Free Electrically Charged Particle 96

97 About Very Low Frequency Propagation 97

98 Very Low Frequency VLF About Surface Propagation - 1 Very Low Frequency Propagated As Surface Waves Through Air & Sea Water. Radio Waves Travel Through The Portion Of The Atmosphere Hugging The Earth Follows Curvature Of Earth Greater The Transmit Power, The Greater The Distance 98

99 Very Low Frequency VLF About Surface Propagation - 2 Does Not Suffer Much Attenuation. [Loss Of Energy] High Levels Of Atmospheric Noise [Heat & Electricity] Used For Long Range Radio Navigation Used For Submarine Communication 3 KHz 30 KHz Frequency Range 99

100 About Low Frequency Propagation 100

101 Low Frequency LF About Surface Propagation - 1 Very Low Frequency Propagated As Surface Waves Through Air Radio Waves Travel Through The Portion Of The Atmosphere Hugging The Earth Follows Curvature Of Earth Greater The Transmit Power, The Greater The Distance 101

102 Low Frequency LF About Surface Propagation - 2 Attenuation/Absorption Is Greater In Daylight. High Levels Of Atmospheric Noise [Heat & Electricity] Used For Long Range Navigation Used Radio Beacons & Navigational Locators. 30 KHz 300 KHz Frequency Range 102

103 About Middle Frequency Propagation 103

104 Middle Frequency MF About Tropospheric Propagation - 1 Middle Frequency Propagated (1) By Line Of Sight From Antenna To Antenna Limited By Curvature Of Earth Middle Frequency Propagated (2) By Broadcast Into Troposphere At Angle Where Reflected Back Down To Earth s Surface Greater Distance Than Line Of Sight 104

105 Middle Frequency MF About Tropospheric Propagation - 2 These Frequencies Absorbed By Ionosphere Distance You Can Cover Is Limited To The Angle At Which You Can Reflect Without Entering Ionosphere Attenuation/Absorption Is Greater In Daylight. Most Often Use Line Of Sight To Reduce Absorption & Increase Control 105

106 Middle Frequency MF About Tropospheric Propagation - 3 Used AM Radio, Maritime Radio, Radio Direction Finding (RDF) & Emergency Frequencies 300 KHz 3 MHz Frequency Range 106

107 About High Frequency Propagation 107

108 High Frequency HF About Ionospheric Propagation - 1 High Frequency Propagated By Higher Frequency Radio Waves Radiated Into The Ionosphere Where They Are Reflected Back To Earth Density Difference Between Ionosphere & Troposphere Cause Signal To Speed Up Then Bounce Back To Earth Allows Greater Distance With Lower Power Output 108

109 High Frequency HF About Ionospheric Propagation - 2 Used Amateur Radio (HAM), Citizen s Band (CB) Radio, International Broadcasting, Military Communication, Long Distance Aircraft, Long Distance Ship, Telephone, Telegraph, Facsimile 3 MHz 30 MHz Frequency Range 109

110 About Very High Frequency Propagation 110

111 Very High Frequency VHF About Line-Of-Sight Propagation - 1 Very High Frequency Transmitted Directly From Antenna To Antenna Antenna Must Be Directional (Facing Each Other) Antenna Must Be Tall Enough Or Close Enough To Avoid Curvature & Terrain Limitations Tricky Radio Transmissions Can Not Be Focused 111

112 Very High Frequency VHF About Line-Of-Sight Propagation - 2 Radio Waves Can Reflect Off Surface Of Earth Or Parts Of Atmosphere These Can Arrive Out Of Order & Distort Signal. Used VHF Television [Channels 2-13], FM Radio, & Aircraft AM Radio 30 MHz 300 MHz Frequency Range 112

113 About Ultra High Frequency Propagation 113

114 Ultra High Frequency UHF About Line-Of-Sight Propagation - 1 Ultra High Frequency Transmitted Directly From Antenna To Antenna Antenna Must Be Directional (Facing Each Other) Antenna Must Be Tall Enough Or Close Enough To Avoid Curvature & Terrain Limitations Tricky Radio Transmissions Can Not Be Focused 114

115 Ultra High Frequency UHF About Line-Of-Sight Propagation - 2 Radio Waves Can Reflect Off Surface Of Earth Or Parts Of Atmosphere. Used UHF Television[Channels 14-69], Mobile Telephone, Cellular Radio, Paging & Microwave Links 300 MHz 3 GHz Frequency Range 115

116 About Super High Frequency Propagation 116

117 Super High Frequency SHF Line-Of-Sight / Space Propagation - 1 Mostly Line-Of-Sight & Some Space Propagation 117

118 Super High Frequency SHF Line-Of-Sight / Space Propagation - 2 Super High Frequency (1) Transmitted Microwave Line- Of-Sight or (2) Transmitted VIA Satellite [SPACE]- A Broadcast Signal Is Received By An Orbiting Satellite; The Satellite Re-broadcasts The Signal Back To Earth Line-Of-Sight Off Satellite 118

119 Super High Frequency SHF Line-Of-Sight / Space Propagation - 3 Used Terrestrial Microwave, Satellite Microwave, & Radar Communication 3 GHz 30 GHz Frequency Range 119

120 About Extremely High Frequency Propagation 120

121 Extremely High Frequency EHF About Space Propagation - 1 Extremely High Frequency Transmitted VIA Satellite [SPACE] A Broadcast Signal Is Received By An Orbiting Satellite; The Satellite Re-broadcasts The Signal Back To Earth Line-Of-Sight Off Satellite 121

122 Extremely High Frequency EHF About Space Propagation - 2 Microwave Used In Scientific Applications & Research Radar, Satellite, & Experimental Communications 30 GHz 300 GHz Frequency Range 122

123 Propagation Summary 123

124 Band Range Propagation Application VLF 3 30 KHz Ground Long-range radio navigation LF KHz Ground Radio beacons and navigational locators MF 300 KHz 3 MHz Sky AM radio HF 3 30 MHz Sky Citizens band (CB), ship/aircraft communication VHF MHz Sky and line-of-sight VHF TV, FM radio UHF 300 MHz 3 GHz Line-of-sight UHF TV, cellular phones, paging, satellite SHF 3 30 GHz Line-of-sight Satellite communication EHF GHz Line-of-sight Long-range radio navigation 124

125 Omnidirectional Antenna 125

126 Omnidirectional Antenna 126

127 Terrestrial Microwave 127

128 Terrestrial Microwave Microwaves Do Not Follow The Curvature Of The Earth Require Line-Of-Sight Transmission & Reception Equipment Antenna s Mounted On High Towers, Mountain Tops, etc. Two Frequencies Required Up/Down Each Frequency Requires Transmitter & Receiver 128

129 Terrestrial Microwave (cont) Receiver & Transmitter For Both Frequencies Are Often Combined Into Same Piece Of Hardware Today A System Of Repeaters Extend Distance By Echoing/Amplifying Signal Original Or Different Frequency Allowed! 129

130 Microwave Antenna 130

131 Types Of Antenna Used For Terrestrial Microwave - 1 Parabolic Dish Antenna Every Line Parallel To The Line Of Symmetry Bounces Off The Dish Into The Focus Extends The Range As Opposed To A Single Receiver. 131

132 Types Of Antenna Used For Terrestrial Microwave - 2 Horn Antenna Transmissions Are Broadcast Up The Stem & Deflected Out In A Narrow Beam. Likewise Beams are Caught In The Horn And Reflected Down The Stem. 132

133 Satellite Communication 133

134 Satellite Communication Satellite Communication Is Like The Line-Of-Sight Microwave Communication One Of The Stations Is A Satellite Orbiting The Earth. The Satellite Acts As A Super High Antenna The Curvature Of The Earth Limitation Is Greatly Reduced. 134

135 Satellite Communication (cont) Span Continents With Single Bounce! Adds Communication Capability To Any Location On Earth. Satellites Expensive Leasing Time/Frequencies Is Relatively Cheap 135

136 Geosynchronous Satellites 136

137 Geosynchronous Satellites Line-Of-Sight Requires Sending & Receiving Units Be Locked Onto Each Other At All Times. Satellites Must Travel At Exactly The Same Speed As Earth s Rotation. Because Speed Is Based On Distance From Planet, Only One One Orbit Is Geosynchronous 22,000 Miles From Earth Surface. 100% Coverage At Least 3 Satellites 120 Degrees. 137

138 Geosynchronous Satellites (cont) Satellite Frequencies In Gigahertz Range. Send Over One Band Receive Over Another Band Uplink Up From Earth To Satellite Downlink Down From Satellite To Earth 138

139 Frequency Bands For Satellite Communications Band Downlink Uplink C GHz GHz Ku GHz GHz Ka GHz GHz 139

140 Microwave Use In Cell Phones 140

141 Cellular Telephone Designed To Provide Stable Communication Between One Or More Mobile Uses Service Provider Must Be Able To Locate & Track A Caller Service Provider Must Be Able to Transfer Caller As He/She Moves Into New Call Area 141

142 Cellular Telephone (cont) Cell Call Made Caller Moves To Cell Border Call Handed Off 142

143 About Cellular Telephone 832 Carriers! Band = 25MHz = 25,000 KHz Carrier Frequencies = 30KHz 25,000 KHz / 30 KHz = 833 Carriers Per Band Each Cell Phone 1 Carrier Up & 1 Carrier Down 833 Carriers / 2 Carriers = 416 Channels Per Band 2 Bands = 832 Channels Available 143

144 About Cellular Telephone 832 Carriers! 2 Bands = 832 Channels Available Some Channels Used For Controls To Prevent Interference, Adjacent Cells Can Not Use The Same Channels Each Cell Normally Has Access To Only 40 Channels MTSO Mobile Telephone Switching Office 144

145 Microwave Use In Wireless LANs 145

146 Inferared 146

147 Infrared Short Range Communication High Frequencies Can't Penetrate Walls Sun's Waves Interfere With It Remotes! Wireless Keyboards! Wireless Mice! 147

148 Impairment Revisited 148

149 Transmission Impairment 149

150 Attenuation Attenuation Loss Of Energy When A Signal Is Transmitted Across A Medium, It Loses Some Of Its Signal Strength Overcoming The Resistance Of The Line. 150

151 Attenuation (cont) Attenuation Loss Of Energy Why An Electrical Line Gets Warm Or Hot After Time. Amplifiers Are Used To Amplify/Regenerate The Signal 151

152 Distortion Distortion Means The Signal Changes Shape. 152

153 Noise Noise Thermal Noise Random Electron Motion Induced Noise From Appliances Cross Talk One Wire Interfering With Another Impulse Noise Short High Energy Spike Lightning, Power Generators, etc. 153

154 Summary 154

155 Note: Radio waves are used for multicast communications, such as radio and television, and paging systems. 155

156 Note: Microwaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. 156

157 Note: Infrared signals can be used for short-range communication in a closed area using line-of-sight propagation such as remote controls. 157

158 The Network Administrator Must Consider Many Things 158

159 When Comparing Media You Should Consider The Following Cost : Materials + Installation Speed : Maximum Number Bits/Second Attenuation Tendency Of Signal To Become Weak/Distorted Over Distance Electromagnetic Interference (EMI) Susceptibility Of Medium To External Magnetic Energy Interference. (Snow : Video & Static : Audio) Security Protection Against Eavesdropping 159

160 Data Communications & Networking CSCI 3342 Dr. Thomas E. Hicks Computer Science Department Trinity University Textbook: Computer Networks By Andrew Tanenbaum Textbook: Data Communications & Networking By Behrouz Forouzan Special Thanks To WCB/McGraw-Hill For Providing Graphics For Many Text Book Figures For Use In This Presentation. 160