Network Warrior, 2nd Edition

Chapter 29. Wireless

Wireless networking is a vast topic. From the basics of how it works to the vast and continuously evolving security concerns, there is no way I could address it all in a book designed to cover many topics. Add to that the complexity of how to design and implement a large-scale corporate roaming environment, and it was a challenge deciding what to include in this chapter. Whole books can be (and have been) written about wireless. I recommend O’Reilly’s own 802.11 Wireless Networks: The Definitive Guide, Second Edition, by Matthew Gast (http://oreilly.com/catalog/9780596001834) for a deeper discussion of this fascinating technology.

Wireless networks come in two flavors: infrastructure and ad hoc. In an infrastructure wireless LAN (WLAN), one or more wireless access points (WAPs) are used to gain access to the network. In this type of environment, all wireless communication is done through the WAPs, even communication between two wireless hosts on the WLAN. For a wireless client to use a WAP, it must first authenticate (if so configured) and then associate with the WAP. A client is only associated with one WAP at a time. If a client goes out of range of one WAP, then associates with another while maintaining its wireless configuration, the client is said to be roaming.

WAPs may be standalone autonomous devices, or they may be lightweight devices that are controlled by a wireless LAN controller. Wireless LAN controllers are common in large deployments, since they ...