In even the simplest 802.11 network, proper configuration of the access points is essential. Without properly configured network interfaces, no traffic will be bridged on to the wired network.
In the early days of 802.11, access points were simple devices. They had a pair of interfaces, and connected wireless devices to an existing wired LAN. Early APs were bridges between the wireless and wired realms, with few additional features. When the first generation of wireless LAN products hit the market, there was a broad separation into cheaper home gateways and expensive business-class products. Products in both classes performed the same functions, although the latter typically used higher-capacity components to provide flexibility and investment protection, as well as the first crude large-scale management tools.
At the dawn of 802.11, APs were initially standalone independent devices. In the early days, wireless LANs offered the ability to have untethered access, but lacked serious security and management capabilities. Although these islands of networking occasionally communicated with each other, they were not often used as part of a large-scale network system because the protocols to enable them to do so had not been developed or tested on a large scale. As wireless networks became more popular and grew larger, flaws in the traditional standalone access point model became apparent.
Sensing a market opportunity, several vendors have built a second generation of wireless network hardware. Newer approaches concentrate management and support functions for APs into an chassis that has the basic functions of an Ethernet switch, which enables the APs themselves to be dumbed-down radio interfaces. Although there are several approaches, the broad category of "lightweight" or "thin" access points plus a control system is often labeled a wireless switch. A great deal of interest has surrounded the switch-based architecture since it was first popularized in late 2002, but the fundamental technology must perform the same functions as first-generation access points.
This chapter discusses, in general terms, how to use access points. It takes a look at a full-featured standalone device, the Cisco 1200 series AP. Although there is a great deal of power in the Cisco 1200, it can be formidable to configure. For a look at the lower end of the market, this chapter looks at the Apple AirPort Express.
Introduction to Wireless Networking
Overview of 802.11 Networks
11 MAC Fundamentals
11 Framing in Detail
Wired Equivalent Privacy (WEP)
User Authentication with 802.1X
11i: Robust Security Networks, TKIP, and CCMP
Contention-Free Service with the PCF
Physical Layer Overview
The Frequency-Hopping (FH) PHY
The Direct Sequence PHYs: DSSS and HR/DSSS (802.11b)
11a and 802.11j: 5-GHz OFDM PHY
11g: The Extended-Rate PHY (ERP)
A Peek Ahead at 802.11n: MIMO-OFDM
Using 802.11 on Windows
11 on the Macintosh
Using 802.11 on Linux
Using 802.11 Access Points
Logical Wireless Network Architecture
Site Planning and Project Management
11 Network Analysis
11 Performance Tuning
Conclusions and Predictions