Network PHY - CablingCablingIssues with cabling LANsTypes of equipment/choices
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Network PHY - CablingMedia is a layer 1 device
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Network PHY - CablingIntroductionWhat are/is media?What categories or types of media exist?What happens to signals sent?What are the common media technologies?How do they compare?
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Network PHY - CablingA real life business exampleAn engineering companyRequires to network the siteDifferent logistical issues on the siteEngineering bay full of engineering equipment
and hence electrical interferenceSeveral depts are remote (across a street)Several depts are within one building
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Network PHY - CablingQuestions to askCostsPerformance including speedReliability and fitness for purposeScalabilitySeveral types of media may be chosenWe would hope they are chosen for the right reasonsFor example, what should we choose for the
engineering bays described earlier?
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Network PHY - CablingAnswers to giveMany different solutions exist, but…Cost, environment, legacy compatibility and
reliability are some of the key factors when choosing media
Faster is often better – and not always more expensive
Many older solutions have been superseded
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Network PHY - CablingMedia typesGuided media - twisted pair (UTP/STP),
coaxial cable (coax), optical fibreUnguided media - radio, infrared, microwavePoint to point, where two devices share the
medium (intermediate repeaters or amplifiers)Multipoint or broadcast where more than two
devices share the medium
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Network PHY - CablingProblems with signalsStrength of the signal decreases with
distance. This gets worse at higher frequencies.
Signal velocity depends on signal frequency, so different frequency components arrive at different times
Noise – thermal (hot electronics “hiss”), cross-talk (sometimes happens on phones), etc.
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Network PHY - CablingTwisted pair (UTP & STP)Digital signal repeaters required every 2 to 3
kmUTP is unshielded twisted pair; it is ordinary
copper telephone wire, the cheapest media for LANs
STP is shielded twisted pair; less prone to interference but more expensive and harder to work with
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Network PHY - CablingTwisted pair (UTP & STP)Insulated copper wires twisted togetherWires acts as a single communication linkOften used in telephone networksUsually used within buildingsComparatively cheap and easy to work withTwists help to avoid cross-talk & noise effects
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Network PHY - CablingSTP Cable
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Network PHY - CablingUTP Cable
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Network PHY - CablingCable CategoriesCat-1 was for telephones and ISDNCat-2 was used by IBM for 4Mbps Token-
RingCat-5e is used for 100Mbps Fast Ethernet
and ATM at 155Mbps, extends to 1000Mbps (Gigabit Ethernet)
Cat-6 is for high speed networks using 200MHz-250MHz signalling
Cat-6a supports 500MHz signalling and thus 10Gbps throughput
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Network PHY - Cabling
Crossover cable reminder
CROSSOVER cables connect 2 PC’s directly together
They cannot be used to connect from a PC to a hub or switch or router – a different type of cable is used for that - a straight through
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Network PHY - CablingBut why a Crossover?To connect similar devicesEg PC to PCSwitch to SwitchSwitch to hub
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Network PHY - CablingCoaxial cableBetter frequency characteristics, higher data
rates, and more immune to interference than twisted pair
Uses: Television distribution,Long distance telephone transmission,Short run computer I/O channels,LANs
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Network PHY - CablingCoaxial Cable
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Network PHY - CablingThinnet Vs Thicknet
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10BASE2 50 Ohm Coaxial Cable10BASE5 Thicknet cable
Network PHY - CablingOptical fibreData rates of 2Gbps or more, over tens of
kilometresLow attenuation (decrease of signal amplitude
over length of a link)Not susceptible to electromagnetic
interference or cross-talkUsed for long haul, metropolitan and rural
trunk lines, secure LANsSee IEEE 802.8 standards for more
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Network PHY - CablingFibre connectors
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Network PHY - CablingFibre Optic Cabling
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Fibre can be manufactured in 40Km lengths.Some fibre-based systems carry 100Gbps signalling.Using Wave-Division Multiplexing, terabit data rates are possible.
Network PHY - CablingSatellite microwaveProvides point to point or point to multi-point
connectivityCommon for TV broadcastingLong distance telephone transmissionPublic and private business networks
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Network PHY - CablingBroadcast radioOmnidirectional – broadcasts all aroundSimple antenna, not like satellite microwaveAntenna alignment allowed to be impreciseGood for data networks where some or all
stations may be mobile
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Network PHY - CablingInfraredLine of sight is neededNo radio-frequency spectrum allocation is
neededProvides point-to-point connectivity (adds security?)
Good for short distancesNo radio interference problems (but sunlight probs)
Speed: from 300Kbps to 4Mbps (IRDA), with IR laser systems over 100Mbps
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Network PHY - CablingConclusionMedia types have been introduced and
discussedThere are choices of how we use our cables
Useful Links:1.http://customcable.ca/cat5-vs-cat6/
2.http://www.howtogeek.com/70494/what-kind-of-ethernet-cat-5e6a-cable-should-i-use/
3.http://en.wikipedia.org/wiki/Optical_fiber
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