1 Discovery 2, Ch 4 Notes

222 Cabling Standards Standards ensure that networks perform to expectations US—IEEE & ANSI/TIA/EIA Canada—CSA (Canadian Standards Assn) Europe—ITU (Int’l Telecom Union)

333 Power over Ethernet IEEE 802.3of 48v DC over twisted pair cable Useful for powering small remote devices

444 UTP Cables TIA/EIA 568 A or B pinouts Order of wiring connections Networks must use all 568A or all 568B Pairs 2 & 3 are reversed Allows construction of crossover cables 568 A at one end, 568 B at other end Straight-through cables are the same at both ends

555 Straight-through cables aka patch cables Used to connect unlike devices Devices that have opposite transmit and receive pins Switch to router PC to hub PC to switch

666 Crossover cables Used to connect like devices Devices that have the same transmit and receive pins Switch to switch Switch to hub Hub to hub Router to router PC to router (router is PC-like) PC to PC

777 Autosensing ports Some devices can detect the transmit and receive pins automatically and reconfigure themselves accordingly

888 UTP Termination Cables are terminated with RJ45 male connectors Connect to RJ45 female jacks on devices or wall

999 Patch Panels Provide a central connection point Allows flexibility in the arrangement of device cabling, especially in the NOC

10 Cable Testing Visual testing is a useful start Must be supplemented by electronic testing Cable tester checks each individual circuit for errors Cable certifier measures precise performance statistics Multimeter measures electronic characteristics

11 Wiring Faults Open Circuit is not completed Failed termination or break in a wire Short Loss of insulation allows individual copper wires to touch each other Reversed Pair The two wires of a pair are crossed at one end of the cable Can only be precisely detected with a wire map Split Pair The wires of two pairs are crossed at one end of the cable Can only be precisely detected with a wire map

12 Attenuation Also called insertion loss Reduction in strength of signal over a distance Natural phenomenon which limits cable length

13 Crosstalk Leakage of signals between pairs NEXT Near end crosstalk Occurs at the transmission end of the cable FEXT Far end crosstalk I bet you can guess where it happens! Crosstalk is caused by untwisting the wire pairs when terminating Re-terminate cable to remove

14 Cabling Best Practices 1.Adhere to standards 2.Never exceed length specifications 3.Install cables away from sources of interference 4.Pay careful attention to termination 5.Test all cabling after installation 6.Label all cables as they are cut and again as they are installed. Record the location of cables in the network documentation.