CWNA guide to wireless LANs 2nd ch01

CWNA Guide to Wireless LANs, Second Edition

Chapter One

It’s a Wireless World

• Explain the advantages and disadvantages of wireless technology

A Day in the Life of a Wireless User: Home

• Hotspots: Locations where wireless data services

are available

• Wireless local area network (WLAN): Essentially

identical to standard local area network (LAN)

– Except devices not connected by wires– Can increase productivity

A Day in the Life of a Wireless User: Car

• Bluetooth wireless standard: Enables short

range wireless communication

– Used in many small devices

A Day in the Life of a Wireless User: Office

• Fixed broadband wireless: Wireless

transmissions between immobile devices

– Typically between office buildings– Utilizes small, customized antennas

• Free space optics (FSO): Alternative to

high-speed fiber optic transmissions

A Day in the Life of a Wireless User: Field

• Handheld devices used to connect to nearest cell tower

– Cell tower connects to local telephone company– Telephone company connects to appropriate

• Such as e-mail servers

A Day in the Life of a Wireless User: On Site

• Radio frequency identification (RFID) tags:

– “Electronic barcodes”– Used to identify items

– Can be read anywhere within range of transmitted radio signal

• Depending on device

A Look at Wireless Technologies• Wireless technology woven throughout many

aspects of life

• Useful to get overview of some current technologies in today’s wireless world

Wireless Local Area Networks (WLANs)

• Wi-Fi (Wireless Fidelity): Based on standard that transmits at up to 11 Mbps

• Computers on WLAN must have wireless network

interface cards (wireless NIC or Wireless adapter)

– Performs same basic functions as standard NIC, plus more

• Access point (AP): Transfers signals between

wireless NICs

• Patch cable connects AP to wired LAN or Internet

Wireless Local Area Networks (continued)

Figure 1-3: Wireless LAN

Wireless Local Area Networks (continued)

Figure 1-4: Home wireless LAN

• Low-power wireless data and voice transmission technology

• Bluetooth devices communicate via radio modules

– Link manager: Software that helps identify other

Bluetooth devices, creates links between devices, and sends and receives data

• Transmit data at up to 1 Mbps over 10 meters• Bluetooth devices within range of each other

automatically connect

– Master and slave

Bluetooth (continued)

• Piconet: Bluetooth network containing a master

and at least one slave

Figure 1-5: Bluetooth device

• WiMax: Signal transmitted between antennas

– Up to 75 Mbps and over up to 35 miles– Fixed Broadband

Telecommunications Links (continued)

• FSO: Transmit at speeds up to 1.25 Gbps over up

to 4 miles

– Line-of-site transmission

Figure 1-6: Free space optics transceiver

Telecommunications Links (continued)

Figure 1-7: Wireless office technologies

Cellular Telephony

• Global Systems for Mobile (GSM)

communications technology: Coverage includes

most of US and parts of Europe and Japan

– Transmission speeds up to 9.6 Kbps

– Information transmitted based on Wireless

Application Protocol (WAP)

• Standard way to transmit, format, and display data for devices like cell phones and handheld devices

Cellular Telephony (continued)

Figure 1-8: Browsing the World Wide Web

Cellular Telephony (continued)

• WAP cell phone runs a microbrowser that uses

Wireless Markup Language (WML) instead of

Radio Frequency Identification (RFID)• Like an electronic barcode:

– Can contain larger amounts of updatable information– Information transmitted via radio waves

– Range typically about 1 foot at 5 Mbps

Figure 1-10: RFID tag

Wireless Technology Categories

Table 1-1: Typical wireless technologies

Wireless LAN Applications: Education• Educational institutions some of first adopters of

WLANs

– Dramatic advantages in teaching and learning

• Wireless LAN connections offer students important degree of freedom

• WLAN technology translates into cost savings for colleges

– Reduces need for wiring and infrastructure– Fewer computer labs necessary

Wireless LAN Applications: Education (continued)

Figure 1-11: Campus access point locations

Wireless LAN Applications: Business• Wireless LAN technologies have significantly

changed how business conducted

– Meetings not confined to conference rooms

– Easier to connect to network resources and Internet– Can create office in space where traditional

infrastructure does not exist

Wireless LAN Applications: Travel• Travel industry perhaps adopted wireless

technologies more than any other industry

– Many airport terminals provide wireless hotspots

– Several large airlines providing wireless capabilities to passengers during flights

– Some airlines use WLAN technology to communicate with aircraft on ground

– Some airlines use WLAN technology to facilitate maintenance tasks

– Some airlines use new wireless data service to send and receive messages

Wireless LAN Applications: Construction

• Wireless technology has greatly benefited construction industry

– Better management of resources– Better management of paperwork

• Construction equipment being fitted with wireless terminals

– “Smart” equipment

– GPS information can provide location information to within centimeters

Wireless LAN Applications: Warehouse Management• New products arrive continuously

– Must be inventoried and stored

• Products being shipped must first be located then transferred to correct location and truck

– Mistakes in inventory or inability to locate items can be devastating

– Mark inventory with RFID tags

• Warehouse management system (WMS)

software: Can manage all activities from receiving

through shipping

– Utilize wireless technology

Wireless LAN Applications: Public Safety

• Public safety departments using WLANs and GSM to communicate information with public safety

– City-owned buildings equipped with APs

– Large volumes of data can be quickly downloaded to vehicles

• e.g., building floor plans, photographs of criminal suspects, and maps

Wireless LAN Applications: Healthcare• Wireless LAN point-of-care computer systems

allow medical staff to access and update patient records immediately

– Document patient’s medication administration immediately

– Extensive use of RFID tags

• Identify healthcare professionals, patients, medications

– System verifies that medication being administered to correct patient in correct dosage

• Eliminates potential errors and documentation inefficiencies

Wireless LAN Applications: Healthcare (continued)

• Documentation process takes place at bedside where care delivered

Wireless LAN Applications: Healthcare (continued)

Figure 1-12: Video pill

Wireless Advantages and Disadvantages: Advantages

• Mobility: Primary advantage of wireless

– “Flatter” organizations: WLANs give team-based

workers ability to access network resources needed while collaborating in team environment

Wireless Advantages and Disadvantages: Advantages

• Easier and Less Expensive Installation:

Installing network cabling in older buildings difficult and costly

– Wireless LAN is ideal solution

– Eliminating need for cabling results in cost savings

• Significant time savings as well

– Allows offices to reorganize easily

• Increased Reliability: Wireless LAN technology

eliminates certain types of cable failures and increases overall network reliability

Wireless Advantages and Disadvantages: Advantages

• Disaster Recovery: Documented disaster

recovery plan vital to every business

– Hot site: Off-site facility that can run business’s

operations if primary site is not available

• Generally maintained by third party• Expensive

– Cold site: Customer provides and installs equipment

• Many businesses use cold sites and WLANs as major piece of disaster recovery plan

– No consideration given to network cabling

Wireless Advantages and

Disadvantages: Disadvantages

• Security: Wireless signals broadcast in open air

– Security for wireless LANs is prime concern

• Unauthorized users might access network

– War driving

• Attackers might view transmitted data

• Employees could install rogue access points

• Attackers could easily crack existing wireless security– Older wireless products have very weak security

features

Wireless Advantages and

Disadvantages: Disadvantages (continued)

• Radio Signal Interference: Signals from other

devices can disrupt wireless transmissions

– Or wireless device may be source of interference for other devices

– e.g., Microwave ovens, elevator motors,

photocopying machines, theft protection devices, cordless telephones

– Solution: Locate source of interference and remove

• Health Risks: Wireless devices emit RF energy

– Not known if or to what extent low levels of RF might cause adverse health effects

• Wireless devices and technologies enable users to roam almost anywhere and remain connected to data and voice networks

• A WLAN, also known as Wi-Fi, functions the same as a standard wired network except devices send radio frequency signals through the air instead of being connected to the network by cabling

• Bluetooth devices communicate using small radio transceivers called radio modules that are built into microprocessor chips

• RFID tags function as electronic barcodes

• Wireless personal area networks (WPANs) cover technologies where the transmission generally extends only a few meters or feet, whereas

wireless local area networks (WLANs) are generally restricted to 112 meters (375 feet)

Summary (continued)

• Wireless LAN applications can be found in

industries in which employees need the freedom to conduct business without being confined to a