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Chapter Four

Chapter Four. Networking Media. Chapter Objectives. Explain concepts related to data transmission and noise Describe the physical characteristics of coaxial cable, STP, UTP, and fiber-optic media Explain the benefits and limitations of different networking media. Chapter Objectives.

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Chapter Four

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  1. Chapter Four Networking Media

  2. Chapter Objectives • Explain concepts related to data transmission and noise • Describe the physical characteristics of coaxial cable, STP, UTP, and fiber-optic media • Explain the benefits and limitations of different networking media

  3. Chapter Objectives • Identify the best practices for cabling buildings and work areas • Describe the methods of transmitting data through the atmosphere • Identify the network media best suited to specific LAN environments

  4. Data Transmission • Information can be transmitted via one of two methods • Analog • Digital • Amplitude • A measure of a signal’s strength

  5. Analog Signal • Uses variable voltage to create continuous waves, resulting in an inexact transmission FIGURE 4-1 Example of an analog signal

  6. Digital Signal • Digital pulses can have a value of 1 or 0 FIGURE 4-2 Example of a digital signal

  7. Data Transmission • Binary system encodes using 1s and 0s • Bits can only have a value of either 1 or 0 • Eight bits together form a byte

  8. Data Transmission • Frequency • Number of times a signal’s amplitude changes over a period of time • Expressed in Hertz (Hz) • Noise • Interference from sources near network cabling

  9. Data Transmission • Attenuate • Loss of signal strength as transmission travels away from source FIGURE 4-3 Analog signal distorted by noise and then amplified

  10. Data Transmission • Regeneration • Process of retransmitting a digital signal • Repeater • Device used to regenerate a signal Figure 4-4 Digital signal distorted by noise and then repeated

  11. Data Transmission • Modem • Name reflects function as modulator/demodulator • Modulates analog signals into digital sounds at the transmitting end for transmission over telephone lines • Demodulates digital signals into analog signals at the receiving end

  12. Media Characteristics • Throughput and bandwidth • Cost • Size and scalability • Connectors • Noise immunity

  13. Throughput and Bandwidth • Throughput is the amount of data the medium can transmit during a given period of time • Also calledcapacity • Bandwidth measures the difference between the highest and lowest frequencies a media can transmit • Range of frequencies is directly related to throughput

  14. Throughput and Bandwidth FIGURE 4-5 A comparison of two digital frequencies

  15. Cost • Cost of installation • Cost of new infrastructure versus reusing existing infrastructure • Cost of maintenance and support • Cost of a lower transmission rate affecting productivity • Cost of obsolescence

  16. Size and Scalability • Specifications determining size and scalability • Maximum nodes per segment (dependent on attenuation) • Maximum segment length • Maximum network length • Latency is the delay between the transmission of a signal and its receipt

  17. Connectors and Noise Immunity • Connector • Connects wire to network device • Noise Immunity • Electromagnetic Interference (EMI) • Radio Frequency Interference (RFI) • Conduits can protect cabling

  18. Network Cabling • Baseband and Broadband Transmission • In baseband transmission, digital signals are sent through direct current (DC) pulses applied to the wire • In broadband transmission, signals are modulated as radio frequency (RF) analog pulses that use different frequency ranges

  19. Network Cabling • Coaxial Cable • Central copper core surrounded by an insulator • Braiding insulates coaxial cable • Sheath is the outer cover of a cable • Foundation for Ethernet network in the 1980s FIGURE 4-6 Coaxial cable

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

  21. Network Cabling • Thicknet (10Base5) • Thicknet • Also called thickwire Ethernet • Rigid coaxial cable used for original Ethernet networks • IEEE designates Thicknet as 10Base5 Ethernet

  22. Network Cabling • Thicknet (10Base5) • Throughput • Cost • Connector • Noise immunity • Size and scalability FIGURE 4-7 Thicknet cable transceiver with detail of a vampire tap piercing the core

  23. Network Cabling Thinnet (10Base2) • Also known as thin Ethernet, was most popular medium for Ethernet LANs in the 1980s • Throughput • Cost • Size and scalability • Connector • Noise Immunity FIGURE 4-8 Thinnet BNC connectors

  24. Network Cabling • Signal Bounce • Caused by improper termination • Travels endlessly between two ends of network • Prevents new signals from getting through FIGURE 4-9 Typical coaxial network using a bus topology

  25. Network Cabling • Twisted-Pair (TP) Cable • Similar to telephone wiring • Consists of color-coded pairs of insulated copper wires twisted around each other and encased in plastic coating • Twists help reduce effects of crosstalk, interference caused by signals traveling on nearby wire pairs infringing on another pair’s signals • Alien Crosstalk occurs when signals from adjacent cables interfere with another cable’s transmission

  26. Network Cabling • Twist Ratio • Number of twists per meter or foot in a twisted-pair cable FIGURE 4-10 Twisted-pair cable

  27. Network Cabling • Shielded Twisted-Pair (STP) • Twisted wire pairs are individually insulated and surrounded by shielding FIGURE 4-11 STP cable

  28. Network Cabling • Unshielded Twisted-Pair • Consists of one or more insulated wire pairs encased in a plastic sheath • Does not contain additional shielding FIGURE 4-12 UTP cable

  29. Network Cabling • To manage network cabling, it’s necessary to be familiar with standards used on modern networks, particularly Category 3 (CAT3) and Category 5 (CAT5) Figure 4-13 CAT5 UTP cable

  30. Network Cabling • STP and UTP • Throughput • Cost • Connector • Noise immunity • Size and scalability FIGURE 4-14 RJ-45 connector, used by both STP and UTP

  31. Network Cabling • Fiber-Optic Cable • Contains one or several glass fibers at its core • Cladding is the glass shield around the core FIGURE 4-15 Fiber-optic cable

  32. Network Cabling • Single-Mode Fiber • Carries single frequency of light to transmit data • Multimode Fiber • Carries many frequencies of light over a single or many fibers FIGURE 4-16 Single-mode and multimode fiber-optic cables

  33. Network Cabling • Fiber-Optic Cable • Throughput • Cost • Connector • Noise immunity • Size and scalability FIGURE 4-17 SMA fiber connector

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