Basics of cabling

January 18, 2018 | Author: Anonymous | Category: Science, Health Science, Immunology
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Network PHY - Cabling Cabling Issues with cabling LANs Types of equipment/choices

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Network PHY - Cabling Media is a layer 1 device

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Network PHY - Cabling Introduction What 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 - Cabling A real life business example An engineering company Requires to network the site Different logistical issues on the site Engineering bay full of engineering equipment and hence electrical interference Several depts are remote (across a street) Several depts are within one building

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Network PHY - Cabling Questions to ask  Costs  Performance including speed  Reliability and fitness for purpose  Scalability  Several types of media may be chosen  We would hope they are chosen for the right reasons  For example, what should we choose for the engineering bays described earlier?

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Network PHY - Cabling Answers to give Many 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key factors when choosing media Faster is often better – and not always more expensive Many older solutions have been superseded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 - Cabling Media types Guided media - twisted pair (UTP/STP), coaxial cable (coax), optical fibre Unguided media - radio, infrared, microwave Point 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 - Cabling Problems with signals Strength 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”), crosstalk (sometimes happens on phones), etc.

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Network PHY - Cabling Twisted pair (UTP & STP) Digital signal repeaters required every 2 to 3 km UTP 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 - Cabling Twisted pair (UTP & STP) Insulated copper wires twisted together Wires acts as a single communication link Often used in telephone networks Usually used within buildings Comparatively cheap and easy to work with Twists help to avoid cross-talk & noise effects

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Network PHY - Cabling STP Cable

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Network PHY - Cabling UTP Cable

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Network PHY - Cabling Cable Categories Cat-1 was for telephones and ISDN Cat-2 was used by IBM for 4Mbps Token-Ring Cat-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 Version2, 09/04/2015

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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 - Cabling But why a Crossover? To connect similar devices Eg PC to PC Switch to Switch Switch to hub

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Network PHY - Cabling Coaxial cable Better 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 - Cabling Coaxial Cable

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Network PHY - Cabling Thinnet Vs Thicknet

10BASE2 50 Ohm Coaxial Cable Version2, 09/04/2015

10BASE5 Thicknet cable Slide 18

Network PHY - Cabling Optical fibre Data rates of 2Gbps or more, over tens of kilometres Low attenuation (decrease of signal amplitude over length of a link) Not susceptible to electromagnetic interference or cross-talk Used for long haul, metropolitan and rural trunk lines, secure LANs See IEEE 802.8 standards for more

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Network PHY - Cabling Fibre connectors

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Network PHY - Cabling Fibre 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.

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Network PHY - Cabling Satellite microwave Provides point to point or point to multi-point connectivity Common for TV broadcasting Long distance telephone transmission Public and private business networks

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Network PHY - Cabling Broadcast radio Omnidirectional – broadcasts all around Simple antenna, not like satellite microwave Antenna alignment allowed to be imprecise Good for data networks where some or all stations may be mobile

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Network PHY - Cabling Infrared Line of sight is needed No radio-frequency spectrum allocation is needed Provides point-to-point connectivity (adds security?) Good for short distances No radio interference problems (but sunlight probs) Speed: from 300Kbps to 4Mbps (IRDA), with IR laser systems over 100Mbps

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Network PHY - Cabling Conclusion Media types have been introduced and discussed There are choices of how we use our cables Useful Links: 1. 2. 3. Version2, 09/04/2015

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