What You re Up Against

Overview

Wi-Fi access points are pretty versatile, and getting moreso all the time. They were originally designed to be wireless hubs, and the vast majority of home office and small office wireless installations still use them as hubs: Central points to which computers are linked wirelessly as part of connecting them into a small network. Such a setup, with a single access point associated with one or more wireless clients in infrastructure mode, is called a basic service set. Probably 95% of all Wi-Fi access points in user hands are operating in infrastructure mode as part of a basic service set.

Some newer access points can also act as Ethernet client adapters (see Chapter 7) which are external clients linked to a device via Ethernet cable. Some can also act as repeaters to extend the range of a wireless link inside the home, though this service falls outside of the Wi-Fi standard and sometimes requires that all participating access points be of the same manufacturer, or sometimes even of the same model.

Some wireless access points have yet a few more tricks up their sleeves- though sometimes those tricks are way up their sleeves and difficult to shake loose. Key among these is the ability of some access points to link two physically separated wired networks via a point-to-point connection, often between buildings, sometimes between locations several miles apart. This ability is called bridging or bridge mode. Schematically, it looks like the setup in Figure 16.1. The details can vary; what I show here is the simplest take on the idea, and the one that I will describe in detail at the end of this chapter.

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Figure 16.1: A Wireless Bridge Linking Two Networks.

With proper setup, good antennas, correct adjustment, and a few prayers to the Wi-Fi gods, this should enable the two networks to pass data seamlessly at up to the maximum throughput 802.11b allows-about 5 Mbps. How fast data moves depends (as always) on equipment make and model, signal strength, and signal quality. The better your signal, the faster those bits will go. Using the AirPlus access points from D-Link, as I'll describe later, can give you throughput as high as 6.5 Mbps, courtesy of Texas Instruments' 802.11b+ chipset.

Before you even think about setting up a Wi-Fi bridge link, be very sure that your knowledge of ordinary Ethernet and TCP/IP networking is as complete as possible. This is a relatively advanced topic. If you're clueless about MAC addresses, subnets, IP addresses, and DHCP servers (to name only a few), you will be lost. Definitely read Chapters 2 and 3 if you haven't already, but in truth, the more you know about networking, the easier it will go.



Jeff Duntemann's Drive-By Wi-Fi Guide
Jeff Duntemanns Drive-By Wi-Fi Guide
ISBN: 1932111743
EAN: 2147483647
Year: 2005
Pages: 181

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