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Physical Media

Physical Media. physical link: what lies between transmitter & receiver guided media: signals propagate in solid media: copper, coax, fiber unguided media: signals propagate freely, e.g., radio signals. Physical Media. Common Cabling. Copper Twisted Pair Unshielded (UTP)

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Physical Media

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  1. Physical Media

  2. physical link: what lies between transmitter & receiver guided media: signals propagate in solid media: copper, coax, fiber unguided media: signals propagate freely, e.g., radio signals Physical Media

  3. Common Cabling • Copper • Twisted Pair • Unshielded (UTP) • CAT-1, CAT-2, CAT-3, CAT-4, CAT-5, CAT-5e • Shielded (STP) • Coaxial Cable • Cable TV cable • Fiber • Single-mode • Multi-mode

  4. Twisted Pair • Most common LAN interconnection • Multiple pairs of twisted wires • Twisting to eliminate interference • More twisting = Higher bandwidth, cost • Standards specify twisting, resistance, and maximum cable length for use with particular link layer

  5. Twisted Pair • 5 categories • Category 1 • Voice only (telephone wire) • Category 2 • Data to 4Mbs (LocalTalk) • Category 3 • Data to 10Mbs (Ethernet) • Category 4 • Data to 20Mbs (16Mbs Token Ring) • Category 5 (100 MHz) • Data to 100Mbs (Fast Ethernet) • Category 5e (350 MHz) • Data to 1000Mbs (Gigabit Ethernet)

  6. Twisted Pair • Common connectors for Twisted Pair • RJ11 (6 pairs) • RJ45 (8 pairs) • Allows both data and phone connections • (1,2) and (3,6) for data, (4,5) for voice • Crossover cables for NIC-NIC, Hub-Hub connection (Data pairs swapped)

  7. UTP • Unshielded Twisted Pair • Limited amount of protection from interference • Commonly used for voice and Ethernet • Voice: multipair 100-ohm UTP

  8. STP • Shielded Twisted Pair • UTP susceptible to radio and electrical interference • To reduce this interference, extra shielding material added to obtain STP • Cables heavier, bulkier, and more $$ • Often used in token ring topologies • 150 ohm STP two pair (IEEE 802.5 Token Ring) • Not as common as UTP

  9. Coaxial cable • Single copper conductor at center • Plastic insulation layer • Highly resistant to interference • Braided metal shield • Support longerconnectivity distances over UTP

  10. Coaxial cable • Thick (10Base5) • Large diameter 50-ohm cable • N connectors • Thin (10Base2) cables • Small diameter 50-ohm cable • BNC, RJ-58 connector • Video cable • 75-ohm cable • BNC, RJ-59 connector • Not compatible with RJ-58

  11. Fiber • Center core made of glass or plastic fiber • Transmit lightversuselectronic signals • Protects from electronic interference, moisture • Plastic coating to cushion core • Kevlar fiber for strength • Teflon or PVC outer insulating jacket

  12. Fiber • Single-mode fiber • Smaller diameter (12.5 microns) • One mode only • Preserves signal better over longer distances • Typically used for SONET or SDH • Lasers used to signal • More expensive • Multi-mode fiber • Larger diameter (62.5 microns) • Multiple modes • LEDs used to signal • WDM and DWDM • Photodiodes at receivers

  13. PL: Fiber connectors • ESCON • Duplex SC • ST • MT-RJ (multimode) • Duplex LC

  14. Wireless • Entire spectrum of transmission frequency ranges • Radio • Infrared • Lasers • Cellular telephone • Microwave • Satellite • Acoustic (see ESE sensors) • Ultra-wide band • http://www.ntia.doc.gov/osmhome/allochrt.html

  15. Protocol Cable Speed Topology Ethernet Twisted Pair, Coaxial, Fiber 10 Mbps Linear Bus, Star, Tree Fast Ethernet Twisted Pair, Fiber 100 Mbps Star LocalTalk Twisted Pair .23 Mbps Linear Bus or Star Token Ring Twisted Pair 4 Mbps - 16 Mbps Star-Wired Ring FDDI Fiber 100 Mbps Dual ring ATM Twisted Pair, Fiber 155-2488 Mbps Linear Bus, Star, Tree What runs on them? Protocol Summary

  16. When connecting 2 nodes, you have 2 choices: Use wires to connect the nodes: What cable to use to connect the transmitter and receiver? Twisted Pair Coax Fiber Wireless transmission Summary

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