Networking Concepts Lesson 03 - Media - Eric Vanderburg

Networking Concepts – Eric Vanderburg ©2005

Chapter 3

Networking Media


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)


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


Transmission

BasebandDigitalOne channelUse repeaters

BroadbandAnalogMultiple channelsUse amplifiers


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


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)


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


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.


Other Hardware

Wall Plate

Patch Panel


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)


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)


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


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


Cabling Concerns

Differing bandwidth requirementsBuilding and Fire codesExisting setupBudgetUpgradeability, Obsolescence, & TCO


Wireless Uses

Temporary connectionsRedundant connectionsNetwork extensionRoamingAccess in difficult areasSupport for handheldsDockingPeripherals


Wireless Networks

LANs – 802.11a,b,gExtended LANs – Microwave, SatelliteMobile – Radio or Cellular

Provided by communications carrier


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


Frequency Ranges

Radio: 10KHz – 1GHzMicrowave: 1GHz – 500GHzInfrared: 500GHz – 1THz


Infrared Technologies

Line of SightReflective (central device)Scatter Infrared

Bounces signalLimited to 30 meters

Broadband Optical Telepoint Networks


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.


Laser Technologies

Requires line of sightNot vulnerable to visible light

interference


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


Radio LAN Technologies

High powered technologiesLong range to horizonTowers used to redirect signalMuch more expensiveFCC licensing required


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)


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)


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.


Wireless

BSA (Basic Service Area) Influence of the WAPsDepends on:

Power of the transmitterEnvironment

BSS (Basic Service Set)Stations belonging to an AP


Wireless Extended LANs

Connects LAN segmentsEliminate leased line costs10x cost of leased lineWork in pairs “half-repeaters”

Optical Half-repeatersRadio Half-repeaters


Wireless Extended LANs

Short Range1-3 miles1-6MbpsSpread Spectrum

Long RangeUp to 25 miles2-100Mbps Infrared or Laser


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


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


802.16a Wireless MAN

WiMax (Worldwide Interoperability for Microwave Access)

70Mbps30 milesMoving car accessBroadband to distant locations


More Microwave technology

CDPD (Cellular Digital Packet Data)19.2kbpsHandheld connections

Low orbit satellites10bpsContinental coverage

Networking Concepts Lesson 03 - Media - Eric Vanderburg

Technology

satellite cable rg

thicknet rg

coaxial cable coax rg

long cable

expensive cable

cable tv

coaxfor broadband rg

ohms impedance rg