Basics of cabling
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Network PHY - Cabling Cabling Issues with cabling LANs Types of equipment/choices
Network PHY - Cabling Media is a layer 1 device
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?
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
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?
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key factors when choosing media Faster is often better – and not always more expensive Many older solutions have been superseded
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
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.
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
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
Network PHY - Cabling STP Cable
Network PHY - Cabling UTP Cable
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
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 - Cabling But why a Crossover? To connect similar devices Eg PC to PC Switch to Switch Switch to hub
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
Network PHY - Cabling Coaxial Cable
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
Network PHY - Cabling Fibre connectors
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.
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
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
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
Network PHY - Cabling Conclusion Media types have been introduced and discussed There 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-ofethernet-cat-5e6a-cable-should-i-use/ 3. http://en.wikipedia.org/wiki/Optical_fiber Version2, 09/04/2015