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Hardware Concepts

Hardware Concepts. Chapter 4. Contents. Explain the different types of network topology Describe the different types of network cabling Describe and distinguish between the 802.2, 802.3, 802.5, and 802.11 IEEE networking standards. Topology. Topology.

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Hardware Concepts

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  1. Hardware Concepts Chapter 4

  2. Contents • Explain the different types of network topology • Describe the different types of network cabling • Describe and distinguish between the 802.2, 802.3, 802.5, and 802.11 IEEE networking standards

  3. Topology

  4. Topology • A topology describes how computers connect to each other

  5. Types of Topologies • Bus • All computers connect via a main line, called a bus cable • Ring • All computers attach to a central ring of cable • Star • All computers connect to a central wiring point, usually a hub • Mesh • Each computer has a dedicated line to every other computer

  6. Types of Topologies

  7. Network Technologies • A network technology is a practical application of a topology to get data from one computer or network to another • Ethernet • Token Ring • FDDI

  8. Bus Topology • Ethernet was the first network technology that used the bus topology • Each computer on the network is connected to the single cable

  9. Bus Topology • If there is a break in the cable, the entire network would stop functioning • It has no fault tolerance to survive a problem

  10. Star Topology • Each computer is connected to a central device such as a hub • If a cable breaks only the one computer is affected

  11. Star Bus Topology • A star bus topology is a hybrid topology • Uses a physical star topology • Uses a logical bus topology • Most common topology used today

  12. Token Ring Topology • Token ring uses a star ring topology • Uses a physical star topology • Uses a logical ring topology • Declining in popularity

  13. Cabling

  14. Coax • Coaxial cable (or coax) contains a central conductor wire, surrounded by an insulating material, which in turn is surrounded by a braided metal shield

  15. EMI • Electro-magnetic interference (EMI) is caused by lights, fans, copy machines, and other devices • EMI corrupts the signal flowing through the cable • The braided shield helps to reduce the effects of EMI

  16. Types of Coax Cable • The Ohm rating is a measure of resistance in the cable and differentiates different types of coaxial cable • RG-8, RG-62, and RG-58 are used in computer networks

  17. RG-8 • RG-8 cable is also called Thick Ethernet • Oldest type of coax still in use • Rated at 50 ohms • Yellow or orange/brown color

  18. RG-62 • RG-62 cable is never installed in networks today • Was used with ARCnet

  19. RG-58 • RG-58 is also called Thin Ethernet • Still in widespread use today

  20. Twisted Pair • Shielded Twisted Pair (STP) and Unshielded Twisted Pair (UTP) are the most common types of cabling used today • Composed of multiple pairs of wires twisted together to reduce interference from adjacent wires, called crosstalk

  21. Shielded Twisted Pair (STP) • Twisted pairs of wires surrounded by shielding to protect them from EMI • Only used in older Token Ring networks

  22. Unshielded Twisted Pair (UTP) • Most common type of cabling used in networks • Twisted pairs of wires surrounded by a plastic jacket • Inexpensive and flexible

  23. CAT Ratings • Twisted pair cabling varies by things like the number of twists per foot • Cables are rated in categories or CAT ratings (or levels)

  24. CAT Ratings

  25. CAT Usage • Most new installations use CAT 5e cable since it is cheaper than CAT 6 cable CAT level CAT level

  26. Fiber Optic • Fiber optic cabling transmits light rather than electricity • Immune to EMI • Very long distances • Consists of the fiber, cladding, and insulating jacket • Defined by fiber and cladding measurements • Most common is 62.5/125 µm • Fiber generally requires two cables

  27. Light Sources • Fiber optic cables use two possible light sources • Light Emitting Diodes (LEDs) – called multimode • Lasers – called single-mode • Supports faster speeds and longer lengths

  28. Networking Industry Standards

  29. IEEE • Institute of Electrical and Electronic Engineers (IEEE) defines industry-wide standards • Organized the 802 committee in February of 1980 to define networking standards • Split up into smaller subcommittees

  30. IEEE Subcommittees There are more subcommittees than listed in this table.

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