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Cabling

Cabling. Issues with cabling LANs Types of equipment/choices. Media is a layer 1 device. 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?. A real life business example.

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Cabling

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  1. Cabling • Issues with cabling LANs • Types of equipment/choices

  2. Media is a layer 1 device

  3. 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?

  4. 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

  5. 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?

  6. 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factors when choosing media • Faster is often better – and not always more expensive • Many older solutions have been superseded

  7. 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

  8. 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”), cross-talk (sometimes happens on phones), etc.

  9. 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

  10. 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

  11. STP Cable

  12. UTP Cable

  13. 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

  14. 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

  15. But why a Crossover? • To connect similar devices • Eg PC to PC • Switch to Switch • Switch to hub

  16. 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

  17. Coaxial Cable

  18. 10BASE2 50 Ohm Coaxial Cable 10BASE5 Thicknet cable Thinnet Vs Thicknet

  19. 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

  20. Fibre connectors

  21. 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.

  22. 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

  23. 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

  24. 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

  25. Conclusion • Media types have been introduced and discussed • There are choices of how we use our cables Useful Links: • http://customcable.ca/cat5-vs-cat6/ • http://www.howtogeek.com/70494/what-kind-of-ethernet-cat-5e6a-cable-should-i-use/ • http://en.wikipedia.org/wiki/Optical_fiber

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