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Chapter03 -- transmission basics and networking media

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Basic Networking Guide

Basic Networking Guide

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  • 1. Chapter 3: Transmission Basics and Networking Media Network+ Guide to Networks
  • 2. Objectives
    • After reading this chapter and completing the exercises, you will be able to:
    • Explain basic data transmission concepts, including full duplexing, attenuation, and noise
    • Describe the physical characteristics of coaxial cable, STP, UTP, and fiber-optic media
  • 3. Objectives (continued)
    • Compare the benefits and limitations of different networking media
    • Identify the best practices for cabling buildings and work areas
    • Specify the characteristics of popular wireless transmission methods.
  • 4. Transmission Basics
    • Transmit means to issue signals to the network medium
    • Transmission refers to either the process of transmitting or the progress of signals after they have been transmitted
  • 5. Transmission Basics
    • Analog and Digital Signaling
      • On a data network, information can be transmitted via one of two signaling methods: analog or digital
        • Both types of signals are generated by electrical current, the pressure of which is measured in volts
  • 6.
    • An analog signal, like other waveforms, is characterized by four fundamental properties: amplitude, frequency,wavelength, and phase
      • A wave’s amplitude
      • Frequency
      • Phase
    Transmission Basics (continued)
  • 7.
    • Digital signals composed of
      • pulses
      • precise
      • positive voltages and zero voltages
    • Data Modulation
      • used to modify analog signals in order to make them suitable for carrying data over a communication path
    Transmission Basics (continued)
  • 8.
      • Modem reflects this device’s function as a modulator/demodulator
        • Modulates digital signals into analog signals
      • Modulation
        • Frequency modulation (FM)
        • Amplitude modulation (AM)
    Transmission Basics (continued)
  • 9.
    • Transmission Direction
      • Simplex
      • Half-duplex
      • Full-duplex
      • Channel
    Transmission Basics (continued)
  • 10.
    • Multiplexing
      • Allows multiple signals to travel simultaneously over one medium
      • In order to carry multiple signals, the medium’s channel is logically separated into multiple smaller channels, or sub channels
      • A device that can combine many signals on a channel, a multiplexer (mux), is required at the sending end of the channel
      • At the receiving end, a demultiplexer (demux) separates the combined signals and regenerates them in their original form
    Transmission Basics (continued)
  • 11.
      • Time division multiplexing (TDM)
      • Wavelength division multiplexing (WDM)
        • WDM enables one fiber-optic connection to carry multiple light signals simultaneously
        • Using WDM, a single fiber can transmit as many as 20 million telephone conversations at one time
      • Statistical multiplexing
    Transmission Basics (continued)
  • 12.
    • Throughput and Bandwidth
      • Throughput is the measure of how much data is transmitted during a given period of time
      • Bandwidth is a measure of the difference between the highest and lowest frequencies that a medium can transmit
        • The higher the bandwidth, the higher the throughput
    Transmission Basics (continued)
  • 13.
    • Baseband and Broadband
      • Baseband is a transmission form in which (typically) digital signals are sent through direct current (DC) pulses applied to the wire
        • Supports half-duplexing
        • Ethernet is an example of a baseband system found on many LANs
    Transmission Basics (continued)
  • 14.
      • Broadband is a form of transmission in which signals are modulated as radio frequency (RF) analog waves that use different frequency ranges
        • Does not encode information as digital pulses
        • Is used to bring cable TV to your home
        • Is generally more expensive than baseband
        • Can span longer distances than baseband
    Transmission Basics (continued)
  • 15.
    • Transmission Flaws
      • Noise is any undesirable influence that may degrade or distort a signal
      • Crosstalk occurs when a signal traveling on one wire or cable infringes on the signal traveling over an adjacent wire or cable
      • Attenuation is the loss of a signal’s strength as it travels away from its source
    Transmission Basics (continued)
  • 16.
      • Latency is a delay between the transmission of a signal and its eventual receipt
        • The most common way to measure latency on data networks is by calculating a packet’s round trip time (RTT), or the length of time it takes for a packet to go from sender to receiver, then back from receiver to sender
        • RTT is usually measured in milliseconds
    Transmission Basics (continued)
  • 17. Media Characteristics
    • Five characteristics are considered when choosing a data transfer media:
      • Throughput
      • Costs
      • Size and Scalability
      • Connectors
  • 18.
        • Noise Immunity
        • The type of media least susceptible to noise is fiber-optic cable
    Media Characteristics (continued)
  • 19.
      • Because of its shielding, most coaxial cable has a high resistance to noise
      • Coaxial cable is more expensive than twisted-pair cable because it requires significantly more raw materials to manufacture
      • The significant differences between the cable types lie in the materials used for their center cores, which in turn influence their impedance
    Coaxial Cable
  • 20.
    • Thicknet (10Base5) Ethernet
      • Also called thick wire Ethernet, is a rigid coaxial cable approximately 1-cm thick that contains a solid copper core
      • Thicknet is sometimes called “yellow Ethernet” or “yellow garden hose”
    Coaxial Cable (continued)
  • 21.
      • IEEE designates Thicknet as 10Base5 Ethernet
      • Thicknet uses a vampire tap and must abide by the 5-4-3 rule of networking.
    Coaxial Cable (continued)
  • 22.
    • Thinnet (10Base2) Ethernet
      • Also known as thin Ethernet
      • Because of its black sheath, Thinnet may also be called “black Ethernet”
    Coaxial Cable (continued)
  • 23.
      • Its core is typically made of several thin strands of copper
      • Thinnet is less expensive than Thicknet and fiber-optic cable, but more expensive than twisted-pair wiring
    Coaxial Cable (continued)
  • 24.
      • Both Thicknet and Thinnet coaxial cable rely on the bus topology, in which nodes share one uninterrupted channel
      • Networks using the bus topology must be terminated at both ends
      • Without terminators, signals on a bus network would travel endlessly between the two ends of the network, a phenomenon known as signal bounce
    Coaxial Cable (continued)
  • 25. Twisted-Pair Cable
      • Twisted-pair cable consists of color-coded pairs of insulated copper wires
      • Every two wires are twisted around each other to form pairs and all the pairs are encased in a plastic sheath
  • 26. Twisted-Pair Cable (continued)
      • The number of pairs in a cable varies, depending on the cable type
      • The more twists per inch in a pair of wires, the more resistant the pair will be to all forms of noise
      • The number of twists per meter or foot is known as the twist ratio
  • 27.
      • Twisted-pair cable is the most common form of cabling found on LANs today
      • It is relatively inexpensive, flexible, and easy to install, and it can span a significant distance before requiring a repeater (though not as far as coax)
    Twisted-Pair Cable (continued)
  • 28.
      • All twisted-pair cable falls into one of two categories: shielded twisted-pair (STP) or unshielded twisted-pair (UTP)
    • Unshielded twisted-pair (UTP)
      • Consists of one or more insulated wire pairs encased in a plastic sheath
    Twisted-Pair Cable (continued)
  • 29.
    • 10BaseT
      • A popular Ethernet networking standard that replaced the older 10Base2 and 10Base5 technologies
      • The “10” represents its maximum throughput of 10 Mbps, the “Base” indicates that it uses baseband transmission, and the “T” stands for twisted pair, the medium it uses
    Twisted-Pair Cable (continued)
  • 30.
    • 10BaseT
      • On a 10BaseT network, one pair of wires in the UTP cable is used for transmission, while a second pair of wires is used for reception allowing full-duplex transmission
    Twisted-Pair Cable (continued)
  • 31.
    • 100BaseT (Fast Ethernet)
      • Also known as Fast Ethernet
      • Uses base band transmission
      • Configured in a star topology
      • 100BaseT networks do not follow the 5-4-3 rule
    Twisted-Pair Cable (continued)
  • 32.
    • 100BaseTX
      • Requires CAT 5 or higher unshielded twisted-pair cabling
      • Within the cable, it uses the same two pairs of wire for transmitting and receiving data
      • Capable of full duplex transmission
    Twisted-Pair Cable (continued)
  • 33. Fiber-Optic Cable
    • Contains one or several glass or plastic fibers at its center, or core
    • Data is transmitted via pulsing light sent from a laser or light-emitting diode (LED) through the central fibers
    • Surrounding the fibers is a layer of glass or plastic called cladding
  • 34.
    • Fiber cable variations fall into two categories:
      • Single-mode
      • Multimode
    Fiber-Optic Cable (continued)
  • 35.
      • Single-mode fiber
        • Uses a narrow core (less than 10 microns in diameter) through which light generated by a laser travels over one path, reflecting very little
        • Allows high bandwidths and long distances (without requiring repeaters)
        • Costs too much to be considered for use on typical data networks
    Fiber-Optic Cable (continued)
  • 36.
      • Multimode fiber
        • Contains a core with a diameter between 50 and 115 microns in diameter; the most common size is 62.5 microns over which many pulses of light generated by a laser or LED travel at different angles
        • It is commonly found on cables that connect a router to a switch or a server on the backbone of a network
    Fiber-Optic Cable (continued)
  • 37.
    • 100BaseFX standard
      • The 100BaseFX standard specifies a network capable of 100-Mbps throughput that uses baseband transmission and fiber-optic cabling
      • 100BaseFX requires multimode fiber containing at least two strands of fiber
    Fiber-Optic Cable (continued)
  • 38.
    • 1000BaseLX standard
      • The most common 1-Gigabit Physical layer standard in use today, can reach 5000 meters and use one repeater between segments
    Fiber-Optic Cable (continued)
  • 39. Cable Design and Management
      • Cable plant
      • Demarcation point (or demarc)
      • Backbone wiring
      • Punch-down block
      • Patch panel
  • 40. Installing Cable
      • Straight-through cable is so named because it allows signals to pass “straight through” between terminations
      • Crossover cable is a patch cable in which the termination locations of the transmit and receive wires on one end of the cable are reversed
  • 41. Installing Cable (continued)
  • 42. Wireless Transmission
    • Wireless LANs typically use infrared or radiofrequency (RF) signaling
    • Characteristics of Wireless Transmission
      • Antennas are used for both the transmission and reception of wireless signals
      • To exchange information, two antennas must be tuned to the same frequency
  • 43. Wireless Spectrum
  • 44. Wireless Transmission (continued)
    • Signal Propagation
      • Line-of-sight (LOS)
      • Signal Degradation
      • Wireless signals also experience attenuation
      • Wireless signals are also susceptible to noise (often called “interference”)
  • 45. Choosing The Right Transmission Medium
      • Most environments will contain a combination of these factors; you must therefore weigh the significance of each
        • Areas of high EMI
        • Distance
        • Security
        • Existing infrastructure
        • Growth
  • 46. Summary
    • Explain basic data transmission concepts
    • Describe the physical characteristics of different cable types
    • Compare the benefits and limitations of different networking media
    • Identify the best practices for cabling buildings and work areas
    • Specify the characteristics of popular wireless transmission methods