IT-113 Structured Cabling Ch

IT-113 Structured Cabling Chapter 1 Introduction to Data Cabling

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Objectives • Define the basic communication system.• List the components of the data communication process. • Identify the various signals of data transfer. • Describe how the electrical characteristics of the transmission media affect data transmission.

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Basics of Cabling • Golden rules of cabling• Importance of reliable cabling• Legacy of proprietary cabling• Increasing cabling demands for higher speeds• Cable design and materials• Communications media• Limitations of cabling• Future of cabling

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Golden Rules of Cabling • Networks never get smaller• Build one system for voice and data• Install more than you need• Use structured-cabling standards• Quality counts; cabling and components• Don’t scrimp on installation costs• Plan for higher speed technologies – 5 yrs• Documentation is a must!!

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Importance of Reliable Cabling • 10 % total network cost is cabling • Life span upwards of 16 years • 70 % of al network problems due to cabling and component technique problems

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Importance of Reliable Cabling – 2 • Cabling is the foundation of any network • Cost of poor cabling – Intermittent problems– Slow access time– PC’s locking up • Is cabling to blame – YES!!!

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Importance of Reliable Cabling – 3 • Is cabling to blame – YES!!! • Why?? – Substandard components– Poor installation techniques • How?? – Drop-rate magnification– 1% drop in Ethernet packets relates to 80% drop in throughput – Wiring problems drop packets

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Legacy of Proprietary Cabling Systems • Vendor specific• No standards existed in the 1980’s• Different equipment/connections – Wang– IBM twinax– Twisted Pair – digital phone systems– Thinnet and thicknet– RS-232 forms– Coaxial cable • Thing of the past, but stil exists in some areas

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Legacy of Proprietary Cabling Systems • Anixter Cables Performance Levels describe performance only • Organizations involved – ANSI– TIA– EIA • Comprehensive standards set – ANSI/TIA/EIA-568-1991– ANSI/TIA/EIA-568-A in 1995– ANSI/TIA/EIA-568-B in 2001

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Cabling and the Need for Speed • 10 Mbps – Ethernet• 16 Mbps – Token ring• 100 Mbps – FDDI, & Fast Ethernet• 155 Mbps – ATM• 655 Mbps – ATM• 1000 Mbps – Gigabit Ethernet• 2.5 Gbps – ATM• 10 Gbps – 10G Ethernet

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Cabling and the Need for Speed WHY ?? • Application size and data transfer rates have increased • Applications are more complex and require more bandwidth to operate • Performance demands on cabling must be able to keep up with these new requirements

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Types of Communication Media • Twisted Pair – UTP • Most common today• 100 ohm Ω ± 15%, 24 AWG, four-pair cable – STP • Standard set by IBM Type 1A cable• Al the cable pairs are shielded from EMI• Performance considerations – Shield must be continuous– All components must be shielded– Shield must be grounded at both ends IAW TIA/EIA-607

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Types of Communication Media • Twisted Pair – ScTP • Hybrid of STP• 100 ohm Ω , 24 AWG, four-pair cable• Foil shield surrounds al the pairs and a drain wire provided for bonding • Individual pairs not shielded• Must use special RJ-45 plugs and jacks• Used in area with high EMI levels

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UTP STP ScTP

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Types of Communication Media • Fiber optic cable• Advantages – Greater transmission distances– Higher bandwidth capability– Not affected by EMI– No crosstalk– More secure • Dark fiber – spare fiber cables “Not Lit-up”

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Types of Communication Media • Single-mode fiber – Used as a backbone cable– One light source only– Long distance communications • Multimode fiber – Used with ATM, FDDI and 10Base-FL applications– Al ows more than one path through the fiber– Types • Step index• Graded index

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Fiber-Optic Cable Single-mode fiber Multimode fiber Dual Fiber Cable

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Types of Communication Media • Coaxial – Used primarily for TV and video distribution now – Difficult to run and terminate– Better protection against EMI than UTP– Higher bandwidth than UTP also

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Coaxial Cable

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Cable Design • Questions to be answered• What types of cable in ceiling?• Cable markings?• Untwist a twisted pair cable?• Shielded or unshielded?• Single-mode or multimode fiber?• NEC ratings on fire safety requirements? – Table 1.2

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Cable Design cont.

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Cable Design cont. • Plenum – Space between false ceiling and structural ceiling– Requires a cable rated for this type of space • Riser – Vertical shaft between two floors– TOWERING INFERNO !!! / chimney effect– Must be fire-stopped on each floor • General purpose – Horizontal cable – wiring closet to wal outlet– Patch cables • Limited use – Single and duplex residences only

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Cable Design cont. • Cable jackets – Normal y polyvinyl chloride (PVC) jacket– Cat 1-3 PVC jacket and insulation– Cat 4 and higher – jacket only, insulation uses other materials such as HALAR, KYNAR, and FEP – Slitting cord– Jacket color – no standard

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Cable Design cont. Cat 5e cutaway diagram

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Cable Design cont. • Cable Markings – Example – 000750 FT 4/24 (UL) c(UL) CMP/MMP VERIFIED (UL) CAT 5e SUPERIOR ESSEX COBRA 2313H – FT – footage indicator– 4/24 – four pair, 24 AWG– (UL), c(UL) – underwriters laboratories listed– CMP/MMP – plenum rating– VERIFIED (UL) CAT 5e – certifies to standard– SUPERIOR ESSEX – manufacturer– COBRA – cable brand– 2313 – Julian date of manufacture – H – manufacturing plant

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Cable Design cont. • Common Abbreviations – NFPA – National Fire Protection Association– NEC – National Electrical Code– UL – Underwriters Laboratories– CSA – Canadian Standards Association– PCC – Premises Communication Cord

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Cable Design cont. • Wire insulation – Excellent dielectric for high frequency signals – Fluorinated ethylene-propylene (FEP), polytetraflourethylene (PTFE/TFE) – plenum rated – High density polyethylene (HDPE) – non- plenum rated

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Cable Design cont. • Wire Insulation colors – Colors are standardized– US color code based on 10 colors– Tip and ring combinations • Tip – white/colored stripe or band • Ring – unique color – 25 possible pair combinations– Table1.3, 1.4

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Cable Design cont. • Twists – Cancels out unwanted EMI on pairs • Crosstalk and other effects – Do not untwist more than ½ inch at any connector – 2 to 12 or > twists per foot • Wire gauge – AWG– 22-26 range– Table 1.5

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Cable Design cont. • Solid versus stranded conductor – Solid has better electrical properties • Used as horizontal cabling – Stranded • More flexible • 20% more attenuation due to skin effect • Normal y used as patch cables • Some networks set up with stranded conductors – Require different connectors– Punch-down blocks require solid conductor

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Cable Design cont. • Cable Length – Attenuation is a problem • Propagation delay • Delay skew – Cable length vs. conductor length • Twists make the four pairs have different lengths • Example – Cat 5e cable -139 ft cable length– Pair 1-2 145 ft – Pair 3-6 143 ft – Pair 4-5 141 ft – Pair 7-8 142 ft

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Data Communications 101 • Bandwidth – Maximum frequency for data transmission • Frequency – Expressed in Hz • Data Rate – Maximum data transmitted in one second – Bps • Table 1.6

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Data Communications 101 cont.

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LAN Throughput vs. Operating Frequency

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What are dB’s • Tenfold logarithmic ratio of power output to power input • 10*log(P1/P2) – power output• 3 db – 50 % change in signal power• Table 1.7• 20*log(P1/P2) – voltage output• 6 db – 50 % change in signal voltage• Table 1.8

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Speed Bumps • Attenuation – The lose of signal as it moves away • Noise – The additional unwanted signals from outside sources • Other – EMI, RFI, Static

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ATTENTUATION • Loss of signal• Conductor resistance• Mutual capacitance• Impedance• Return loss

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Noise • Resistance unbalance• Capacitance unbalance• Crosstalk• Twist requirement

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Crosstalk • Near-End (NEXT) – same end as source– 20-30 meters • Far End (FEXT) – End opposite the source • Equal-Level Far-End (ELFEXT) – End of cable pairs opposite source

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Crosstalk cont. • Pair-to Pair • Power-Sum

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Other Hindrances • External Interference• Attenuation-to Crosstalk Ratio (ACR) – Also cal ed signal-to-noise ratio (SNR)– Calculated value– Difference between crosstalk and attenuation • Propagation Delay – Nominal Velocity of Propagation (NVP)– Normally 60-90 % speed of light • Delay Skew

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• ACR • Delay Skew

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SUMMARY • Complete Unit 1-1 Lab• Homework Week 1 – Research the fol owing cable types • Cat 3, Cat 5e, Cat 6, Cat 7• Create a table with the fol owing specifications for each cable type • Impedance, Attenuation, NEXT, FEXT, Pair-to-pair crosstalk, Power-sum crosstalk, Data rate, Operating frequency, Twist ratios, and cost – Answer the questions on the handout.

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