1. Wi-Fi IEEE 802.11 Standards 802.11a 802.11b 802.11g 802.11n 802.11ac
Note: This slide is a simple overview of the standards described in this section.

2. 802.11 Standards define how devices communicate
Some define how to secure communications
Each sub-standard by a IEEE subcommittee

3. Hardware
Adapters
Wireless Ethernet NICS
PCI, PC Card, external USB

4. Wireless access point (WAP)
Basic WAP operates like a hub at Layer 1
Often multiple devices in one box
High-speed hub or switch
Bridge
Router

5. Figure 16.4 Wireless client configuration utility

6. Wireless Network Modes
Ad hoc mode
Also called peer-to-peer mode
Uses a mesh topology
Independent Basic Service Set (IBBS)
Teaching Tip
Remind the students of the mesh topology they studied in Chapter 3.

7. Wireless Network Modes
Infrastructure mode
Uses one or more access points
Similar to a wired star topology
Basic service set (BSS)
Serviced by a single WAP
Extended service set (ESS)
Serviced by two or more WAPs
Teaching Tip
Point out that Infrastructure mode
Requires more planning
Is suited for business networks
Is suitable for networks sharing dedicated resources

8. Speed Dependent on a few factors Standard used by wireless devices
Distance
Interference
Dead spots
Teaching Tip
Please mention that the “chicken wire” in stucco buildings can degrade, if not entirely block, wireless signals. We experience this every day with a WAP in the house and a wireless host in the office—and both buildings swathed in stucco. The distance from the WAP to the wireless NIC is no more than 25 feet, but we did a great deal of tweaking and changing of the equipment and settings before achieving desired speeds.

9. Basic Service Set Identifier (BSSID)
Most basic infrastructure mode network
BSS is one WAP and one or more nodes
BSSID same as the MAC address of WAP
IBSS nodes (ad hoc mode) 48-bit string
BSSID in every packet

10. Service Set Identifier (SSID)
Another level of naming
Standard name applied to BSS or IBSS
Sometimes called a network name

11. Extended Service Set Identifier (ESSID)
Wi-Fi network with multiple WAPs (ESS)
Most Wi-Fi devices use term SSID

12. Broadcasting Frequency
Potential for interference from other wireless devices
Tech must know frequencies of other wireless devices
Original standards use 2.4-GHz frequency

13. Broadcast Methods
Original IEEE standard used spread-spectrum radio waves
Broadcasts data in small, discrete chunks
Used different frequencies within a range
Note:
See the spread-spectrum methods in the next three slides.

14. Three different spread-spectrum broadcasting methods
DSSS Direct Sequence Spread Spectrum
(faster but uses more bandwidth)
FHSS Frequency Hopping Spread Spectrum
(slower but uses less bandwidth)
OFDM Orthogonal Frequency Division Multiplexing
(latest and most commonly used)

15. Orthogonal frequency-division multiplexing (OFDM)
Latest method
Combines multiple frequencies of DSSS with FHSS’s hopping capability
Later standards use this

16. Channels (2.4Ghz band) A portion of the spectrum
standard defined 14 channels
Different countries may limit channels
Note:
It may be necessary to move WAPs to other channels to avoid overlap.

17. Channels (2.4Ghz band) In U.S. WAP may use channels 1 – 11
There is overlap
Most WAPs default to channel 1, 6, or 11
Channels (5Ghz band)
Non issue
Over 40 channels
Automatic channel switching
Note:
It may be necessary to move WAPs to other channels to avoid overlap.

18. CSMA/CA Carrier sense multiple access/collision avoidance
Access method
Allows multiple devices to share network media
Wireless devices cannot detect collisions
Two collision avoidance methods
Distributed coordination function (DCF)
Point coordination Function (PCF)
Note:
Review how CSMA/CD works for wired networks, then compare with wireless networks.
Only DCF is currently implemented.

19. 802.11b Data throughput up to 11 Mbps Range up to 300 feet Popular
2.4-GHz frequency is crowded
More likely to have interference from other wireless devices

20. 802.11a Device on market after 802.11b
Different from all other standards
5-GHz frequency range
Up to 54 Mbps
Short range (~150 feet)
Never as popular as b
Incompatible with b

21. 802.11g Up to 54 Mbps Range of 802.11b (~300 feet)
Backward compatible with b
WAP can service both b and g
All g network runs in native mode
Add b devices
Mixed mode
All communications drop to 11 Mbps max

22. 802.11n Multiple in/multiple out (MIMO)
Four at 150Mbps = 600 Mbps
Many WAPs use transmit beamforming
Dual-band WAPs run at 5 GHz and 2.4 GHz
Some WAPs support a devices
Teaching Tip
Point out the interesting Tech Tip on the standard on page 436. This standard is not explicitly listed in the CompTIA Network+ Exam Objectives, but it is included in the Key Terms list for this chapter, and is an important protocol to watch as new devices appear.

23. 802.11ac Upgrade of 802.11n Operates exclusively in 5GHz range
Increased channel bonding
Faster data transfers
Eight MIMO streams (2x n)
Up to 7 Gbps
Teaching Tip
Point out the interesting Tech Tip on the standard on page 436. This standard is not explicitly listed in the CompTIA Network+ Exam Objectives, but it is included in the Key Terms list for this chapter, and is an important protocol to watch as new devices appear.

25. Wireless Networking Security
Problem
Easy-to-install devices have no default security
Network data packets are in radio waves
Three wireless security methods
MAC address filtering
Wireless authentication
Data Encryption
Note:
Details on the three wireless security methods are on the following slides.

26. MAC address filtering Allow or Deny specific MAC addresses
Problem: hackers can spoof MAC addresses
MAC address must be updated for changes

27. Wireless Authentication
Users with proper credentials get access
Can use a centralized security database
802.1X standard
RADIUS Server
Extensible Authentication Protocol (EAP) password encryption
Note:
Wireless authentication can use Active Directory accounts. More on RADIUS Servers in following slide.

28. Wireless Authentication
RADIUS server
Provides authentication for network access
Client computer is called a supplicant
WAP is the Network Access Server (NAS)
NAS contacts RADIUS server
RADIUS server checks security database
User given access if credentials are correct

29. Figure 16.7 Authenticating using RADIUS

30. Wireless authentication problem areas
Connection must be secure
PPP between supplicant and WAP/NAS
IPSec between WAP/NAS and RADIUS server
RADIUS server uses an authentication protocol
EAP-TLS
EAP-TTLS
PEAP
WAP and wireless NICs must use same authentication protocol

31. Figure 16.8 Authentication using RADIUS with protocols in place

32. Figure 16.9 Setting EAP authentication scheme

33. Data Encryption Wired Equivalent Privacy (WEP)
64- or 128-bit encryption algorithm
Problems
Easily cracked
Key is static and shared
No user authentication

34. Data Encryption Wi-Fi Protected Access (WPA)
Dynamic encryption key generation
Issued per-user and per-session
Temporal Key Integrity Protocol (TKIP)
128-bit encryption key
Problem: key can be broken

35. Data Encryption Wi-Fi Protected Access 2 (WPA2)
Amendment of standard by i
Issued per-user and per-session
Uses Advanced Encryption Standard (AES)
128-bit block cipher
Not completely hack proof
Deters casual hackers
Longer is better!

36. Power over Ethernet (PoE)
Power and Ethernet signals via Ethernet ports
Good for WAPs far from power outlets
Both WAP and switch must comply with PoE

37. Implementing Wi-Fi

38. Site Survey What wireless devices are already there?
Radio bands in use
Existing SSIDs and channels
Unique SSIDs
Separate channels within same radio band
Locate Interference Sources
Create sketch and identify interference sources
High-interference area may require n
May need multiple WAPs to avoid dead zones
Teaching Tip
Because setting up a wireless network is very basic and easy to do, consider doing a demonstration of the setup of both a WAP and a client. Bring in a wireless access point, a laptop (if you cannot do this on a classroom computer), and a wireless network adapter (USB), and walk students through this part of the chapter. Discuss the SSID, the default router address, and so on. If you can do this, it will go a long way toward helping students understand the concept. If this is not feasible, slides showing screenshots from the set up work well, too.

39. Figure 16.10 Site survey with interference sources noted

40. Figure 16.12 Selecting ad hoc mode in wireless configuration utility

41. Setting up an Infrastructure Network
Placing Access Points
Omni-directional and centered
Radio waves flow outward
Standard straight-wire dipole antennae
Off-center position
Gaining gain
Focusing the wave with directional antenna

42. Figure 16.13 Room layout with WAP in the center

43. Figure 16.14 Replacement antenna on WAP

44. Setting up an Infrastructure Network
Access Point Configuration
Configure the SSID (ESSID) and beacon
Configure MAC address filtering
Configure encryption
Configure channel and frequency
Configure the client

45. Figure 16.17 Setting the beacon interval

46. Figure 16. 18 MAC address filtering configuration
Figure MAC address filtering configuration screen for a Linksys WAP

47. Figure 16.19 Encryption key configuration screen on Linksys WAP

48. Figure 16. 20 Encryption screen on client wireless
Figure Encryption screen on client wireless network adapter configuration utility

49. Figure 16.21 Encryption screen with RADIUS option

50. Figure 16.22 Changing the channel

51. Figure 16.23 Selecting frequency

52. Extending the Network Adding a WAP Wireless Bridge Repeating bridges
Point-to-point
Point-to-multipoint
Repeating bridges
Bridges with access point and router functions

53. Verify the Installation
Move traffic between computers
Always verify installation before leaving

54. Figure 16.25 Linksys wireless bridge device