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Networking Concepts Lesson 03 - Media - Eric Vanderburg
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Networking Concepts – Eric Vanderburg ©2005
Chapter 3
Networking Media
Networking Concepts – Eric Vanderburg ©2005
Cable Characteristics
Bandwidth Rating Max Segment Length Segments per network Devices per segment Interference Susceptibility (EMI & RFI) Connection Hardware Cable Grade (PVC or Plenum Grade Teflon) Bend radius Cost (Material, Installation, & Maintenance)
Networking Concepts – Eric Vanderburg ©2005
Signal Degradation
Reduce EMI/RFIDo not place copper media next to
Fluorescent lightsGenerators/motorsHigh-voltage electrical wire
Proper installationUse quality cableUse shielded cablingUse repeaters to strengthen signal on long
cable runs
Networking Concepts – Eric Vanderburg ©2005
Transmission
BasebandDigitalOne channelUse repeaters
BroadbandAnalogMultiple channelsUse amplifiers
Networking Concepts – Eric Vanderburg ©2005
Coaxial Cable (Coax)
RG-6 - Used for satellite cable RG-8 - Thicknet RG-11 – 75 ohm, Thicknet, handle higher power RG-58 /U - 50 ohm, with a solid copper wire core. RG-58 A/U* - 50 ohm, with a stranded wire core. RG-58 C/U* - Military version of RG-58 A/U. RG-59 - 75 ohm, for broadband transmission such
as cable TV. RG-62 - 93 ohm, primarily used for ArcNet.
*Only these are part of the IEEE specification for Ethernet networks
Networking Concepts – Eric Vanderburg ©2005
Coaxial Cable (Coax)
Thicknet (10base5) ½ inch thick RG-11 or RG-8 Vampire tap AUI (Attachment Unit Interface) - 15 pin DB-15
Thinnet (10base2) BNC (British Naval Connector) 50 ohms impedance RG-58
Coax for Broadband (RG-59, 75 Ohm)
Networking Concepts – Eric Vanderburg ©2005
Twisted Pair
Twists reduce crosstalkUTP (Unshielded Twisted Pair) 10baseTSTP (Shielded Twisted Pair)
Foil wrapped around wiresPhone line (RJ-11)TP Network cable (RJ-45)100 Meter max length
Networking Concepts – Eric Vanderburg ©2005
Twisted Pair Categories
Cat1 – voice only, before 1982 Cat2 – 4 wires, 4Mbps Cat3 – 4 wires, 10Mbps, 3 twists/foot Cat4 – 8 wires, 16Mbps Cat5 – 8 wires, 100Mbps Cat5e – 8 wires, 1Gbps, full-duplex Cat6 – 8 wires, 1Gbps Cat7 – 8 wires, shielded, 1Gbps
*AWG (American Wire Gauge) – Telephone is usually 22, 24, or 26. Specifies wire type.
Networking Concepts – Eric Vanderburg ©2005
Other Hardware
Wall Plate
Patch Panel
Networking Concepts – Eric Vanderburg ©2005
Fiber Optic
Signal sent by light No eavesdropping No interference Two cables needed for full duplex Surrounded by kevlar Max length: 2-100 km 1Gbps & 10Gbps implementations Difficult to install Expensive (Cable, Install, Maintenance)
Networking Concepts – Eric Vanderburg ©2005
Fiber Optic Connectors
ST (Straight Tip) SC (Straight Connection)MT-RJ
two cables in one RJ-45 clone
SMA (Subminiature Type A)MIC (Medium Interface Connector)LC (Link Control)
Networking Concepts – Eric Vanderburg ©2005
Fiber Optic cable types
Single mode Laser based Spans longer distance One piece of glass Core: 2-9 microns
Multi-mode LED based Shorter distance Multiple pieces of glass Core: 25-200 microns
View Cables and prices at: http://www.cableorganizer.com/fiber-optic-jumpers/fiber-optic-multimode50.htm
Networking Concepts – Eric Vanderburg ©2005
Quick Comparison
Type Length Bandwidth Installation Interference Cost
UTP 100 meters 10Mbps-1Gbps Easy High Cheapest
STP 100 meters 16Mbps-1Gbps Moderate Moderate Moderate
Thinnet 185 meters 10Mbps Easy Moderate Cheap
Thicknet 500 meters 10Mbps Hard Low Expensive
Fiber 2-100 kilometers 100Mbps-10Gbps Moderate None Most Expensive
Networking Concepts – Eric Vanderburg ©2005
Cabling Concerns
Differing bandwidth requirementsBuilding and Fire codesExisting setupBudgetUpgradeability, Obsolescence, & TCO
Networking Concepts – Eric Vanderburg ©2005
Wireless Uses
Temporary connectionsRedundant connectionsNetwork extensionRoamingAccess in difficult areasSupport for handheldsDockingPeripherals
Networking Concepts – Eric Vanderburg ©2005
Wireless Networks
LANs – 802.11a,b,gExtended LANs – Microwave, SatelliteMobile – Radio or Cellular
Provided by communications carrier
Networking Concepts – Eric Vanderburg ©2005
Electromagnetic Fundamentals
Lower frequency = slower, less data, longer distance
Higher frequency = faster, more data, shorter distance
Highest frequencies need line of sight & use tight beams
Networking Concepts – Eric Vanderburg ©2005
Frequency Ranges
Radio: 10KHz – 1GHzMicrowave: 1GHz – 500GHzInfrared: 500GHz – 1THz
Networking Concepts – Eric Vanderburg ©2005
Infrared Technologies
Line of SightReflective (central device)Scatter Infrared
Bounces signalLimited to 30 meters
Broadband Optical Telepoint Networks
Networking Concepts – Eric Vanderburg ©2005
Infrared Transmission
Diffused The infrared light transmitted by the sender unit fills the area. The receiver unit located anywhere in that area can receive
the signal. Directed
The infrared light is focused before transmitting the signal Increases the transmission speed.
Directed point-to-point Highest transmission speed Receiver is aligned with the sender unit. The infrared light is
then transmitted directly to the receiver.
Networking Concepts – Eric Vanderburg ©2005
Laser Technologies
Requires line of sightNot vulnerable to visible light
interference
Networking Concepts – Eric Vanderburg ©2005
Radio LAN Technologies
Narrow Band Devices use known single frequency Unregulated bands (902-928MHz,2.4GHz,5.72-5.85GHz) No line of sight needed Range of 70 meters Possible to eavesdrop High susceptibility to RFI
Networking Concepts – Eric Vanderburg ©2005
Radio LAN Technologies
High powered technologiesLong range to horizonTowers used to redirect signalMuch more expensiveFCC licensing required
Networking Concepts – Eric Vanderburg ©2005
Spread Spectrum Technologies
Uses multiple frequencies Less interference Redundancy
Frequency Range: 902-928MHz,2.4GHz Frequency Hopping
Changes at regular intervals Lower bandwidth, more secure
Direct-sequence Modulation Send different data chunks along multiple
frequencies Low frequencies (just above noise)
Networking Concepts – Eric Vanderburg ©2005
802.11
802.11a 54Mbps 5GHz
802.11b 11Mbps 2.4GHz
802.11e QOS
802.11g 54Mbps 2.4GHz WPA Support
802.11i WPA & other
encryption Support 802.11n
300Mbps 2.4GHz
*WPA (Wi-Fi Protected Access)
Networking Concepts – Eric Vanderburg ©2005
Ad Hoc Wireless
Broadcasting/Flooding Suppose that a mobile user A wants to send data to another user B in the same area. When the packets containing the data are ready, user A broadcasts the packets. On receiving the packets, the receiver checks the identification on the packet. If that receiver was not the correct destination, then it rebroadcasts the packets. This process is repeated until user B gets the data.
Temporary Infrastructure In this method, the mobile users set up a temporary infrastructure (mapping). But this method is complicated and it introduces overheads. It is useful only when there is a small number of mobile users.
Networking Concepts – Eric Vanderburg ©2005
Wireless
BSA (Basic Service Area) Influence of the WAPsDepends on:
Power of the transmitterEnvironment
BSS (Basic Service Set)Stations belonging to an AP
Networking Concepts – Eric Vanderburg ©2005
Wireless Extended LANs
Connects LAN segmentsEliminate leased line costs10x cost of leased lineWork in pairs “half-repeaters”
Optical Half-repeatersRadio Half-repeaters
Networking Concepts – Eric Vanderburg ©2005
Wireless Extended LANs
Short Range1-3 miles1-6MbpsSpread Spectrum
Long RangeUp to 25 miles2-100Mbps Infrared or Laser
Networking Concepts – Eric Vanderburg ©2005
Microwave Networking
Higher transmission than radioLine of sightFCC approvalRF Hazard Assessment
(determine RF levels at a site)Motorola's WLAN product (ALTAIR)
Uses low powered microwave radio signals18GHz
Networking Concepts – Eric Vanderburg ©2005
Microwave Networking
Terrestrial microwave Between 2 locations Relay towers to cover long distances 4-6GHz or 21-23GHz 1-50 miles 10Mbps Vulnerable to weather disturbance
Satellite microwave Propagation delay Must have or lease a satellite
(gov’t approval, expensive) Global Easy to eavesdrop 11-14GHz 10Mbps Vulnerable to EMI, Jamming, and weather
Networking Concepts – Eric Vanderburg ©2005
802.16a Wireless MAN
WiMax (Worldwide Interoperability for Microwave Access)
70Mbps30 milesMoving car accessBroadband to distant locations
Networking Concepts – Eric Vanderburg ©2005
More Microwave technology
CDPD (Cellular Digital Packet Data)19.2kbpsHandheld connections
Low orbit satellites10bpsContinental coverage