This document provides an overview of wireless networking standards and implementations. It describes how wireless networks use radio waves to communicate and follow the same OSI layers as wired networks. It outlines several IEEE 802.11 wireless standards including 802.11a, b, g, and n. It also discusses how Wi-Fi networks can operate in ad-hoc or infrastructure modes and how CSMA/CA is used to allow multiple devices to share the wireless medium. Finally, it covers common wireless security methods like MAC address filtering, wireless authentication, and data encryption using WEP.

1. Wireless Networking
Chapter 16

2. Objectives
• Explain wireless networking standards
• Describe the process for implementing Wi-
Fi networks
• Describe troubleshooting techniques for
wireless networks

3. • Historic/Conceptual
– Wireless network uses radio waves as the media
• Convenient
• Sometimes the only network option
• Same OSI layers as wired networks
• Same [upper layer] protocols
• Different methods for accessing the media
• IEEE 802.11 wireless Ethernet standard
– Wi-Fi
– Most common implementation

4. • Wi-Fi Standards
– Wi-Fi IEEE 802.11
• 802.11a
• 802.11b
• 802.11g
• 802.11n

5. • Certified by Wi-Fi Alliance
– 300 member companies
– Design and manufacture wireless networking
products
– Certification should ensure compatibility
between manufacturers
– Troubleshooting section at end of this chapter
brings out proprietary nature of some devices

6. • 802.11
– Standards define how wireless devices
communicate
– Some define how to secure communication
– Each sub-standard has name of a IEEE
subcommittee
• Wireless Fidelity (Wi-Fi)

7. • Wireless Network Modes
– Ad hoc mode
• Also called peer-to-peer mode
• Uses a mesh topology
• Independent Basic Service Set (IBBS)
– Two or more wireless nodes communicating in ad hoc mode
• Infrastructure mode
– Uses one or more access points
– Similar to a wired star topology
– Basic service set (BSS)
• Served by a single WAP

8. • CSMA/CA
– Carrier sense multiple access/collision avoidance
(CSMA/CA)
– Access method to allow multiple devices to share
network media
– Review how CSMA/CD works for wired networks
• Each device listens on media
– If no or low signal, media is free
– If signal above a threshold, media is busy
• If media is busy, device waits the length of the current
frame plus the interframe space (IFS) period

9. • Wireless Networking Security
– Problem
• Easy-to-install devices have no default security
• Network data packets are in radio waves
– Easy to capture
– Easy to read

10. • Three wireless security methods
– MAC Address Filtering
• Limits access to specific NICs
• “Accepted users” list of MAC addresses
• List in table stored in WAP
• Data packets with other MAC addresses are rejected

11. – Wireless Authentication
• Only users with proper credentials have access
• Can use a centralized security database (like Active
Directory)
• Requires extra steps for wireless users

12. – Data Encryption
• a. Data Encryption Using WEP
– Wired Equivalent Privacy (WEP)
– 64- or 128-bit encryption algorithm
– Scrambles data packets
– Problems
» Easily cracked
» Only works on two lowest OSI network layers