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Chapter 3: Networking Media

Chapter 3: Networking Media. Learning Objectives. Define and understand technical terms related to cabling, including attenuation, crosstalk, shielding, and plenum Identify three major types of both network cabling and wireless network technologies

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Chapter 3: Networking Media

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  1. Chapter 3:Networking Media

  2. Learning Objectives • Define and understand technical terms related to cabling, including attenuation, crosstalk, shielding, and plenum • Identify three major types of both network cabling and wireless network technologies • Understand baseband and broadband transmission technologies and when to use each continued

  3. Learning Objectives • Decide what kinds of cabling and connections are appropriate for particular network environments • Describe wireless transmission techniques used in LANs • Describe signaling technologies for mobile computing

  4. Network Cabling:Tangible Physical Media • Provides a medium across which network information can travel in the form of a physical signal, whether it is a type of electrical transmission or some sequence of light pulses

  5. Primary Cable Types • Coaxial cable • Twisted-pair (TP) cable • Unshielded (UTP) • Shielded (STP) • Fiber-optic

  6. Bandwidth rating Maximum segment length Maximum number of segments per internetwork Maximum number of devices per segment Interference susceptibility Connection hardware Cable grade Plenum rating Bend radius Material costs Installation costs General Cable Characteristics

  7. Primary Techniques for Sending Signals across a Cable • Baseband transmission • Broadband transmission

  8. Baseband Transmission • Uses digital signals sent over a cable without modulation • Sends binary values (0s and 1s) as pulses of different voltage levels • Entire bandwidth of the cable is used to transmit a single data signal • Limits any single cable strand to half-duplex transmission continued

  9. Baseband Transmission • Signal flow can be bi-directional • Uses repeaters to restore the signal to its original strength and quality before retransmitting it to another cable

  10. Broadband Transmission • An analog transmission technique which may use multiple communication channels simultaneously • Each data channel is represented by modulation on a particular frequency band, for which sending or receiving equipment must be tuned • Signal flow is one-way only; two channels are necessary for computers to send/receive data continued

  11. Broadband Transmission • Uses amplifiers to detect weak signals, strengthen those signals, and then rebroadcast them • Primary approaches to supporting two-way broadband communications • Mid-split broadband • Dual-cable broadband • Offers higher bandwidths, but generally more expensive than baseband systems

  12. The Importance of Bandwidth • The faster the connection, the better

  13. Coaxial Cable • Uses a center conductor -- wrapped by an insulating layer, surrounded by a braided wire mesh and an outer jacket or sheath -- to carry high-bandwidth signals such as network traffic or broadcast television frequencies

  14. Coaxial Cable • Uses shielding to increase the viability of the signals that pass through a cable by absorbing stray electronic signals or fields • Less susceptible to interference and attenuation than twisted-pair cabling, but more so than fiber-optic • A connector must cap each end of the cable, and a terminator must screw into each end

  15. Types of Coaxial Cable for Ethernet • Thin Ethernet (thinnet, thinwire, cheapernet, 10Base2) • Thick Ethernet (thicknet, thickwire, 10Base5)

  16. Thinwire Ethernet • Thin, flexible cable about 0.2” in diameter • Easy to work with • Relatively inexpensive to build or buy • Well suited for small or constantly changing networks • Uses BNC T-connectors to attach directly to networking devices and computers’ network adapter cards

  17. Thinwire Ethernet

  18. Radio Government (RG) Specifications • Coaxial cable designation that reflects coaxial cable’s original use as a conveyance for radio frequency data and signals

  19. Radio Government (RG) Specifications

  20. Thinwire Ethernet Cable

  21. Thickwire Ethernet • Uses a rigid cable about 0.4” in diameter (“frozen yellow garden hose”) • Rarely used except as a backbone for a new network installation (due to expense, large diameter, and lack of flexibility) • Uses a vampire tap to attach a device to the cable, which in turn attaches to a transceiver; transceiver attaches to a drop or transceiver cable that plugs into an attachment unit interface (AUI)

  22. Attaching to Thinwire Ethernet Cable

  23. Attaching to Thickwire Ethernet Cable

  24. Running Thickwire Cable

  25. Thickwire Ethernet Cable

  26. Coaxial Cable Characteristics • Can handle moderate to serious bandwidth • Supports intermediate to moderately long cable runs • Relatively affordable • Resistant to interference; relatively safe from electronic “eavesdropping”

  27. Twisted-pair Cable • Consists of one or more pairs of insulated strands of copper wire twisted around one another • Importance of twists • Improve resistance to interference • Limit the influence of crosstalk

  28. Types of TP Cable • Unshielded twisted-pair (UTP) • Contains one or more pairs of insulated wires within an enclosing insulating sheath • Follows the ANSI/EIA/TIA 568 standard • Prone to crosstalk • Shielded twisted-pair (STP) • Encloses each pair of wires within a foil shield, as well as within an enclosing insulating sheath • Supports higher bandwidth over longer distances than UTP • Has no set of standards

  29. Types of TP Cable

  30. Twisted-pair Network Cabling Schemes • Commonly employ RJ-45 telephone connectors • Typical elements (often in a wiring center) • Punchdown blocks • Patch panels • Wall plates • Jack couplers

  31. RJ-45 Connector

  32. Patch Panels and Punchdown Blocks

  33. 10BaseT’s Networking Characteristics

  34. Fiber-optic Cable • Uses pulses of light sent along a light-conducting fiber at the heart of the cable to transfer information • Sends data in one direction only; two cables are required to permit data exchange in both directions • Consists of a slender cylinder of glass fiber(s), called the core, surrounded by a concentric layer of cladding material and then by an outer sheath

  35. Fiber-optic Cable

  36. Primary Types of Fiber-optic Cables • Single-mode cables • Include only one glass fiber at the core • Cost more • Work with laser-based emitters but span the longest distances • Multi-mode cables • Incorporate two or more glass fibers at the core • Cost less • Work with light emitting diodes (LEDs) but span shorter distances

  37. Fiber-optic Cable Advantages • Immune to interference • Highly secure; eliminates possibility of electronic eavesdropping • Good medium for high-bandwidth, high-speed, long-distance data transmissions

  38. Fiber-optic Cable Drawbacks • High cost • Difficult installation

  39. Fiber-optic Cable Characteristics

  40. Fiber-optic Media Connectors • ST (straight tip) • SC (straight connection) • MIC (medium interface connector) • SMA (subminiature type A)

  41. Cable Selection Criteria • Bandwidth • Budget • Capacity • Environmental considerations • Placement • Scope • Span

  42. Comparison of General Cable Characteristics

  43. The IBM Cabling System • Numeric cabling designations (Type 1 through Type 9) developed by IBM • Types 2 and 9 are the most commonly used networking cables • IBM cable connector is the unique feature; any two connectors are able to plug into each other

  44. IBM Cable Types

  45. Wireless Networking: Intangible Media • Depends on transmission at some kind of electromagnetic frequency through the atmosphere to carry data transmissions from one networked device to another • Appears most frequently in conjunction with wired networks

  46. Capabilities of the Wireless World • Creates temporary connections to existing wired networks • Establishes back-up or contingency connectivity for existing wired networks • Extends a network’s span beyond the reach of wire- or fiber-optic-based cabling • Permits certain users to roam with their machines, within certain limits

  47. Commercial Applications for Wireless Networking • Ready access to data for mobile professionals • Delivery of network access into isolated facilities • Access in environments in which layout and settings change constantly • Improved customer services in busy areas • Network connectivity in facilities where in-wall wiring would be impossible to install or prohibitively expensive

  48. Types of Wireless Networks • Local area networks (LANs) • Extended LANs • Mobile computing

  49. Wireless LAN Applications • Still necessary to attach a network interface to a computer, but the interface attaches to an antenna and an emitter rather than to a cable • Requires an access point device to bridge wireless components and the wired network

  50. Wireless Access Point Device

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