1. 1 Physical Media

2. 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

3. 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. 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. 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. 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. 7 UTP Unshielded Twisted Pair –Limited amount of protection from interference –Commonly used for voice and Ethernet Voice: multipair 100-ohm UTP

8. 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. 9 Coaxial cable Single copper conductor at center Plastic insulation layer Highly resistant to interference –Braided metal shield –Support longer connectivity distances over UTP

10. 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. 11 Fiber Center core made of glass or plastic fiber Transmit light versus electronic signals –Protects from electronic interference, moisture Plastic coating to cushion core Kevlar fiber for strength Teflon or PVC outer insulating jacket

12. 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. 13 PL: Fiber connectors ESCON Duplex SC ST MT-RJ (multimode) Duplex LC

14. 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. 15

16. 16 What runs on them? Protocol Summary ProtocolCableSpeedTopology EthernetTwisted Pair, Coaxial, Fiber10 MbpsLinear Bus, Star, Tree Fast EthernetTwisted Pair, Fiber100 MbpsStar LocalTalkTwisted Pair.23 MbpsLinear Bus or Star Token RingTwisted Pair4 Mbps - 16 MbpsStar-Wired Ring FDDIFiber100 MbpsDual ring ATMTwisted Pair, Fiber155-2488 MbpsLinear Bus, Star, Tree

17. 17 Summary 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