network phy - cabling cabling issues with cabling lans types of equipment/choices version2,...

Network PHY - CablingCablingIssues with cabling LANsTypes of equipment/choices

Version2, 21/04/23 Slide 1

Network PHY - CablingMedia is a layer 1 device


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?


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


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?


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Many older solutions have been superseded


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


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.


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


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


Network PHY - CablingSTP Cable


Network PHY - CablingUTP Cable


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


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


Network PHY - CablingBut why a Crossover?To connect similar devicesEg PC to PCSwitch to SwitchSwitch to hub


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


Network PHY - CablingCoaxial Cable


Network PHY - CablingThinnet Vs Thicknet


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


Network PHY - CablingFibre connectors


Network PHY - CablingFibre Optic Cabling


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


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


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


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


network phy - cabling cabling issues with cabling lans types of equipment/choices version2,...

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