ITNW 1333 -- Microsoft Networking Essentials

Course Syllabus

Chapter 3

Networking Media

Cabling Media

Cables ferry signals between computers
Allow communication between users
"Highway of the network"
"Glue" that bonds networks together
Differing physical characteristics
Limitations of each type

Wireless Media

Used due to:
- Distance limitations
- Physical obstructions
- Mobile users
Still more expensive than wired
Becoming more attractive for users

Primary Cable Types

Three major types:
- Coaxial cable
- Twisted pair cable ( TP )
  - Unshielded ( UTP )
  - Shielded ( STP )
- Fiber-optic cable

General Cable Characteristics

Bandwidth
- Bits or bytes/unit time
- Megabytes per second ( Mbps )
Attenuation
- Signal weakens becomes unreadable
- Maximum segment length
- Hardware to capture & regenerate
Maximum # of segments
- Latency (Longest tolerable delay of signal arrival)
Maximum # of devices per segment
- Insertion loss
  - Each device attached adds to attenuation
  - True maximum = rated maximum - Sum[insertion loss]
Interference susceptibility
- Electromagnetic ( EMI )
  - Transformers, motors
- Radio frequency ( RFI )
  - TV, radio stations
- Four levels
  - None, low, moderate, high
Connection Hardware
- Connectors must match cable type
- Connector cost must be considered
- Ease of attachment
- Specialized equipment required
- Should you build or buy?
Cable Grade
- Building & fire code requirements
- Combustibility & toxicity ratings
- Type of cladding
- Type of insulation
- Polyvinyl chloride ( PVC ) not used
Plenum
- Space between false & real ceiling
- Cables here must be plenum-rated
- Coated with Teflon
- Low combustibility & toxicity
- Conduit not required
Cable Bend Radius
- Damaged or destroyed when exceeded
- Fiber optic & heavy duty coaxial
- Generally more than 600 per foot
- Understand specific cable limits
- Do not exceed these limits
Material Costs
- Cables have cost per unit length
- Remember building & fire codes
- Cable is less than half total cost
- Plan ahead for faster technology
- More expensive cable now will save reinstallation costs later
Installation Costs
- Labor & equipment costs can mount up
- Figure costs of:
  - Design
  - Materials
  - Installation
  - Troubleshooting

Baseband Transmission

Bi directional using digital encoding
Single fixed frequency
Entire bandwidth for each signal
All devices use one channel
Signal decreases with length (attenuation)
Baseband systems like Ethernet
Use repeaters to amplify signals
Restores strength & quality
Sends signal out on another cable
Increases span of network

Broadband Transmission

Uses analog techniques to encode

Continuous electrical or optic waves

Multiple channels on a single cable

Amplifiers are used to:

Strengthen & rebroadcast signal

To support two-way communication:

Mid-split uses a single cable
- Different frequencies for each channel
Dual cable uses two cables
- One each for receive & transmit

Coaxial Cable

For years "coax" was king
Easy to install
Inexpensive
Easy way to extend the network
"Thinnet", "thinaux"
Single conducting core
Surrounded by insulation
Overlaid with metal braided shield
Covered by outer wrapper (sheath)
Good protection from EMF, RFI

Types of Coaxial Cable

Thin Ethernet
- "Thinnet, thinwire, cheapernet"
- 10Base2
Thick Ethernet
- "Thicknet, thickwire"
- 10Base5

IEEE

Institute of Electrical & Electronics Engineers
Designate cable as: 10Base2, 10Base5
Total bandwidth: 10 megabits per second
Base: type of signaling
Maximum segment length: 2, 5 meters

Thin Ethernet Environment

Radio Government specifications ( RG )
Thinnet is RG-58
- 50 ohm impedance (Electrical resistance to current flow
Central conductor varies
- Solid, braided

Thickwire Ethernet

Rigid coaxial cable
Covered with bright yellow Teflon
" Frozen yellow garden hose"
"Standard Ethernet" was 1st used
Now least used

Thickwire Environment

Vampire tap attaches to cable
Transceiver attaches to tap
Attachment Unit Interface(AUI) attaches from transceiver to NIC
Transceiver cables can be 50 meters long

Ethernet Coax Requirements

Each cable end needs a connector
Female BNC for thick & thinwire
Terminator on ends of connectors
- To "soak up" signal
- Prevent "bounce"

Deciding on Coaxial Media

Handles moderate to serious bandwidth
Supports medium to long runs
- Thin 185 meters
- Thick 500 meters
Affordable
Resistant to interference & eavesdropping

Twisted Pair Cable

Basic twisted pair ( TP )
- One or more pairs of wire
- Twisted around one another
- Resistant to interference
- Limits signals influence on other pair ("Crosstalk")

Twisted Pair Types

Unshielded twisted pair (UTP)

Shielded twisted pair (STP)

1, 2, 4, 6, 8 pairs network cable

Available in 50-100 pair cable

STP & UTP Cable

Unshielded Twisted Pair (UTP)

IEEE Ethernet specification
10BaseT
T means UTP
Most popular form of LAN cabling
Maximum segment length of 100 meters
Electronic Industries Association (EIA)
Telecommunication Industries Association(TIA)
American National Standards Institute (ANSI)
ANSI/EIA/TIA 568 Standard
RJ-45 Plug and Jack

568 UTP Categories

1-Voicegrade telephone cabling
2-Voicegrade to 4 Mbps 4 pairs
3-Voicegrade to 10 Mbps 4 pairs
4-Datagrade to 16 Mbps 4 pairs
5-Datagrade to 100 Mbps 4 pairs

Shielded Twisted Pair (STP)

Wire braid shield
Metal foil shield
Reduces crosstalk & interference
Improves transmission characteristics
No standard comparable to 568

Twisted Pair Elements

Distribution racks
Punchdown blocks
Patch panels
Wall plates
Jack couplers

TP Block & Patch Panel

Patch panel (shown on left)
Punchdown block (shown on right)

10BaseT Ethernet Characteristics

Characteristic	Value
Maximum cable length	100 meters (328 ft)
Bandwidth	10Mbps
Bend radius	Not subject to limitations
Installation/maintenance	Easy to install, no need to reroute, most flexible
Cost	Least expensive of all cabling options
Connector type	RJ-45
Interference rating	Low (most susceptible of all cables)

Fiber-Optic Cable

Bundle of glass or plastic fibers
Sends signals on pulses of light
Immune to interference
Eliminate electronic eavesdropping
High bandwidth, speed, long distance
Plastic fiber has higher attenuation
Plastic fiber more damage resistant
Plastic fiber spans less distance
One direction per fiber in both types
Send & receive fiber in both types

Fiber-Optic Cable Characteristics

Characteristic	Value
Maximum cable length	2 Km (6562ft) to 100 Km(62.14mi)
Bandwidth	100Mbps to 1Gbps
Bend radius	30 degrees/ft
Installation/maintenance	Difficult to install and reroute, sensitive to strain and bending
Cost	Most expensive of all cabling options
Connector type	Several types: ST, SC, MIC, SMA
Interference rating	None: least susceptible of all cable types

Fiber-Optic Cable Connectors

ST - straight tip
SC - straight connection
MIC - medium interface connector
SMA - subminiature type A

Fiber-Optic Cable

Single Mode - single fiber core
Multi-mode - two or more fiber cores
- Light emitting diodes
- Shorter distances

Cable Selection Criteria

Bandwidth - how fast must the network be?
Budget - how much money can be spent for cabling?
Capacity - how much traffic must the network carry?
Environment - interference, security issues
Placement - cable routing, building codes
Scope - how many devices must be connected?
Span - how much distance?
Extremes
- Fiber-optic - money no object, need is great
- UTP, thinnet - quick, cheap, easy network needed

Cable Comparison

Type	Max Length	Bandwidth	Installation	Interference	Cost
UTP	100m	10-100Mbps	Easy	High	Cheapest
STP	100m	16-1000Mpbs	Moderate	Moderate	Moderate
10Base2	185m	10Mbps	Easy	Moderate	Cheap
10Base5	500m	10Mbps	Hard	Low	Expensive
Fiber	2-100km	100Mbps-10Gbps	Very hard	None	Most expensive

The IBM Cable System

Unique connectors
Both male & female combined
Types 1-9
American Wire Gauge (AWG) standards
Large wire diameter = smaller AWG #

Wireless Networking

Intangible media
Use is increasing
Cost is decreasing
Hybrid networks use cable & wireless
Mobile users

The Wireless World

Temporary connections to wired LAN
Backup connectivity to wired LAN
Extend span of wired LAN
Permit users to roam
More expensive

Wireless Applications & examples

Mobile users (doctors, delivery persons)
Disaster areas (FEMA, battery power)
Changing environments (film studios)
Customer service (Hertz check in)
Impossible wiring (historical buildings)

Types of Wireless Networks

LANs
- Roving users
- Changing environments
- In impossible wiring situations
Extended LANs
- Extend beyond wired limits
Mobile computing
- Radio
- Cellular phones

Wireless LAN Applications

Use of an antenna and emitter by user
Use of a transceiver by cabled LAN
Access point device by cabled LAN

Wireless LAN Transmission

Send & receive signals via atmosphere
Waves in the electromagnetic spectrum
Frequency measured in Hertz
Frequency affects the amount and speed of data transmission
- High frequency carries more data faster over shorter distances
- Low frequency carries less data more slowly over longer distances

Wireless Data Frequencies

Radio (10 KHz to 1 GHz)
Microwave (1 GHz to 500 GHz)
Infrared (500 GHz to 1 THz)
Wireless Applications by Frequency

Wireless LAN Technologies

Wireless LANs

Infrared & Laser
Narrowband & High-Powered single-frequency radio
Spread-spectrum radio

Infrared & Laser LAN Technologies

Line of sight networks
- Clear view between transmitter/receiver
Reflective wireless networks
- Optical device transceivers to hub
Scatter infrared networks
- Bounce transmissions off walls & ceilings
Broadband optical telepoint networks
- High-speed wide bandwidth
Virtual docking
- Portable devices connect to wired LAN
Infrared is hampered by 100ft range
Prone to interference from visible light

Narrow Band Single Frequency

Low power radio communications
Range of 70 meters
Federal Communication Commission
Solid barriers can interfere
Other radio traffic can interfere

High Power Single Frequency

Transmit as far as the horizon
Repeater towers extend range
Usually purchased from AT&T, GTE
Security is a big concern

Spread-Spectrum Radio LANs

Use multiple frequencies simultaneously
Frequency hopping
Switches data at regular intervals
Direct sequence modulation
- Breaks data into chips
- Simultaneous transmission on different frequencies

Wireless Extended LAN

Wireless bridges
- Connect networks up to 3 miles apart
Permits linking of locations
Longer range bridges are available
- Connect networks up to 25 miles apart
Can transport both voice and data

Microwave Technologies

Terrestrial Microwave Systems

Terrestrial - "of the earth"
Mounted on tall buildings, mountains
Line of sight
Tight beam, high frequency
Relay can extend across continent

Satellite Microwave Systems

Geosynchronous satellites in orbit
23,000 miles above earth
Propagation delays
Leased frequencies
Routinely encrypted

Trends in Wireless Networking

Belief that IEEE will approve 802.11
Cellar packet radio
Cellar digital packet data (CDPD)
Low orbit satellites
Narrow-band sockets