Introduction
them the knowledge necessary to successfully design, implement,
secure, manage, and troubleshoot an 802.11 wireless LAN. Both
groups have things to learn, and both groups are actively moving
towards WLAN expertise. The first group consists of the legacy
Ethernet LAN engineers. These are the “wireline” folks who know
about switches, routers, and firewalls. They know how to move data
through wires, but moving it through the air is new territory. The
second group consists of the telephony folks who have been creating
the cellular phone network for many years. They know how to move
signals through the air, but moving data is new territory.
Today there are a number of tools available to help engineers observe
the behavior of communicating devices in the air. These "wireless
LAN analyzers" offer a broad range of features and capabilities, and a
WLAN engineer must be knowledgeable in the use of an analysis tool,
and in the interpretation of the packet level decodes that the analyzer
presents. In this book you'll see examples of frame level traces that
will show the behavior of wireless communicators in action.
Why should you learn about the 802.11 standards? Why should you
challenge yourself to demonstrate your knowledge through professional
certification? The answer is that 802.11 WLAN technology is, today,
the focal point in an almost unimaginable global technology
convergence, and, without an 802.11 foundation, communication
engineers (LAN and telephony) are going to be at a shocking
disadvantage in the years to come. Now, this statement should not be
taken to mean that the 802.11 standards are going to become universal
and pervasive the way TCP/IP and the Internet did during the 1990's.
Perhaps they will, and perhaps they won't. There are many other
competing standards in the field today: 802.16 WiMAX, 802.20, 3G
cellular with EV-DO, UltraWideband, and more. However, as of the
publication of this book, the 802.11 standards have risen to a position
of prominence and they're going to serve, at the least, as a springboard
into an evolving set of future communication systems.
We're going to see a convergence of cell phone and WLAN networking
over the next several years. When you're inside a building your cell
phone will roam onto the in-building 802.11 network and realize high-
speed data transfer capabilities. In your car you'll roam back onto the
cellular network. This is the realm of Voice-over-WLAN (also called
