CWNA Guide to Wireless

illnurturedtownvilleΚινητά – Ασύρματες Τεχνολογίες

21 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

62 εμφανίσεις

CWNA Guide to Wireless
LANs, Second Edition

Chapter One

It’s a Wireless World

2

Wireless Networks

First Meeting Agenda

1.
Syllabus and Intro.

2.
How to access class resources in your computer

3.
Let’s get acquainted (forming groups)


Name


Industry certification


Networking or IT courses


Interests


Why you are taking the class


Expectations of yourself


Expectations of the instructor and the class

4.
WebCT Login


3

Objectives


Describe how wireless technology is used in daily
activities


Tell how wireless local area networks are used in
applications such as education, business, travel,
construction, and other areas


Explain the advantages and disadvantages of
wireless technology

4

Real Life Wireless






What did Texas Department of Transportation do?

5

A Day in the Life of a Wireless User:
Home


Wireless data communication
has been the driving force in
the 21
st

century


Hotspots
: Locations where wireless data services are
available


World
-
Wide growth rate: 350% a year


By 2007 revenue from hotspots will exceed $9 billion.


Wireless local area network (WLAN):

Essentially identical
to standard local area network (LAN)


Compare Ethernet LAN devices to Wireless LAN devices


Except devices not connected by wires


Can increase productivity (By how much?)


How do you use wireless at home?


6

A Day in the Life of a Wireless User:

Car


Bluetooth wireless standard:
Enables short
range wireless communication


Used in many small devices


How is Bluetooth used in a car
?


Bluetooth on the Road.

7

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


Otherwise known as
WiMax



Free space optics (FSO):

Alternative to high
-
speed
fiber optic transmissions

8

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
resources


Such as e
-
mail servers

9

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 if anywhere within range of transmitted
radio signal


Depending on device

10

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

11

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

12

Wireless Local Area Networks
(continued)

Wireless LAN

13

Wireless Local Area Networks
(continued)

Home wireless LAN

14

Bluetooth


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

Piconet:

Bluetooth network containing a master and
at least one slave

15

Telecommunications Links


Integrated Services Digital Networks (ISDN):

Transmits at 256
Kbps


T
-
1 lines:
Transmit at 1.544 Mbps


Cable modems:

Use television cable connection


Digital subscriber lines (DSL):

Use telephone
lines


WiMax:

Signal transmitted between antennas


Up to 75 Mbps and over up to 35 miles


Fixed Broadband

16

Telecommunications Links (continued)


FSO:

Transmit at speeds up to 1.25
Gbps
over up
to 4 miles


Line
-
of
-
site transmission

Free space optics transceiver

17

Telecommunications Links (continued)

Wireless office technologies

18

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

19

Cellular Telephony (continued)


WAP cell phone runs a
microbrowser
that uses
Wireless Markup Language (WML)
instead of
HTML


WAP gateway
or
proxy:

Translates between WML
and HTML

WAP communications

20

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

RFID tag

http://news.bbc.co.uk/2/hi/science/nature/4545252.stm


21

Wireless Technology Categories

Typical wireless technologies

22

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

23

Wireless LAN Applications: Education
(continued)

Campus access point locations

24

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

25

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

26

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

27

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

28

Wireless LAN Applications: Public
Safety


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


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

29

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

30

Wireless LAN Applications: Healthcare
(continued)


Documentation process takes place at bedside
where care delivered


Improves accuracy


Hospital personnel have real
-
time access to latest
medication and patient status information


Wireless technology also used in other medical
areas:


e.g., video pills

31

Wireless LAN Applications: Healthcare
(continued)

Video pill

32

Wireless Advantages and
Disadvantages: Advantages


Mobility:
Primary advantage of wireless
technology


Enables individuals to use devices no matter where
users roam within range of network


Increasingly mobile workforce is characteristic of
today’s business world


WLANs give mobile workers freedom while allowing
them to access network resources


“Flatter” organizations: WLANs give team
-
based
workers ability to access network resources needed
while collaborating in team environment

33

Wireless Advantages and
Disadvantages: Advantages
(continued)


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

34

Wireless Advantages and
Disadvantages: Advantages
(continued)


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

35

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

36

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

37

Summary


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

38

Summary (continued)


Two popular technologies are WiMax and free
space optics (FSO)


Handheld devices can send and receive wireless
signals using the Global System for Mobile (GSM)
communications technology


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)

39

Summary (continued)


Wireless LAN applications can be found in
industries in which employees need the freedom to
conduct business without being confined to a
specific location


Wireless LANs have significant advantages,
including increased mobility, easier and less
expensive network installations, increased network
reliability, and disaster recovery


Some of the disadvantages of wireless LANs
include security, radio signal interference, and
health concerns