Network Cabling

1
Network Cabling

• Coaxial Cable coax
• Foundation for Ethernet network in the 1980s TP
  has replaced
• Central copper core (carries signal) surrounded
  by an insulator
• Braiding shields against noise and grounds signal
• Sheath is the outer cover of a cable

FIGURE 4-6 Coaxial cable
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Network Cabling

• Coaxial Cable continued
• Has high resistance to interference from noise
• Can carry signal farther than TP before
  amplification is needed, but not as good as fiber
• More expensive than TP
• Generally supports a lower throughput
• Also requires that each end of its segments be
  terminated with a resistor

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Network Cabling
TABLE 4-1 Types of coaxial cable
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Network Cabling

• Thicknet (10Base5)
• Thicknet
• Also called thickwire Ethernet
• Rigid coaxial cable used for original Ethernet
  networks
• IEEE designates Thicknet as 10Base5 Ethernet
• 10 10Mbps baseband max segment length 500
  meters (1640 feet)
• Rarely used on modern networks
• Difficult to manage
• Rigid
• 10 Mbps throughput restriction

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Network Cabling

• Thicknet (10Base5)
• Throughput
• 10Mbps
• Cost
• gt thin, lt fiber
• Connector
• Noise immunity
• High resistance
• Size and scalability
• Max 100 nodes per segment

FIGURE 4-7 Thicknet cable transceiver with detail
of a vampire tap piercing the core
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Network Cabling

• Thinnet (10Base2)
• Also known as thin Ethernet, was most popular
  medium for Ethernet LANs in the 1980s
• 10Mbps, baseband, 200 m
• Rarely used on modern networks
• Replaced by TP
• More flexible than thicknet

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Network Cabling

• Thinnet (10Base2)
• Throughput-10Mbps
• Cost - lt thick / fiber, gt TP
• Size and scalability max 30 nodes per segment
• Connector BNC (British Naval Connector)
  barrel/T
• Noise Immunity better than TP, but not as good
  as thicknet

FIGURE 4-8 Thinnet BNC connectors
8
Network Cabling

• BUS topology
• Small lans
• Doesnt scale well
• Not fault tolerant
• Hard to troubleshoot
• Signal Bounce
• Caused by improper termination
• Travels endlessly

FIGURE 4-9 Typical coaxial network using a bus
topology
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Network Cabling

• Twisted-Pair (TP) Cable like telephone wiring
• Consists of color-coded pairs of insulated copper
  wires twisted around each other and encased in
  plastic coating
• One wire in the pair carries the signal
  information while the other is grounded and
  absorbs interference
• Twists help reduce effects of crosstalk,
  interference caused by signals traveling on
  nearby wire pairs infringing on another pairs
  signals
• Alien Crosstalk occurs when signals from adjacent
  cables interfere with another cables
  transmission
• Occurs when cables are packed together in a
  conduit

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Network Cabling

• Twist Ratio
• Number of twists per meter or foot in a
  twisted-pair cable
• The more twists per inch, the more resistant the
  pair will be to forms of noise

FIGURE 4-10 Twisted-pair cable
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Network Cabling

• Differences in TP
• Twist ratio
• of wire pairs (1-4200)
• Grade of copper used
• Type of shielding and material used
• Early vs. modern networks
• Early had 2 wire pairs one to send and one to
  receive
• Modern have 4 pairs with gt 1 pair for both
  sending and transmitting data simultaneously
• Most common form of cabling used in todays
  networks

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Network Cabling

• Shielded Twisted-Pair (STP)
• Consists of twisted wire pairs that are not only
  individually insulated, but also surrounded by a
  shielding made of metallic substance (foil)
  between pairs and jacket (sheath)

FIGURE 4-11 STP cable
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Network Cabling

• Unshielded Twisted-Pair
• Consists of one or more insulated wire pairs
  encased in a plastic sheath
• Does not contain additional shielding
• Less expensive
• Less resistance to noise

FIGURE 4-12 UTP cable
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Network Cabling

• Characteristics of TP
• 10BaseT 10Mbps, baseband, TP (IEEE)
• Relatively inexpensive
• Easy to install
• Can span a significant distance before needing a
  repeater
• Not as good as coax
• Most often implemented in a STAR configuration
• Can handle faster throughput (as compared to
  coax)
• More prone to physical damage than coax

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Network Cabling

• TIA (Telecomm. Industry Assoc.) and EIA
  (Electronic Industry Assoc.) finalized
  specifications for TP into a standard dividing TP
  into categories (CAT3, CAT5, etc.)

Figure 4-13 CAT5 UTP cable
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Network Cabling

• Categories of TP wiring

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Network Cabling

• STP and UTP
• Throughput
• 20Kbps 1Gbps (or more)
• Cost varies
• Features, STP
• Connector - RJ-45
• Noise immunity
• STP better
• Size and scalability
• Max segment length is 100m (328)

FIGURE 4-14 RJ-45 connector, used by both STP and
UTP