Introduction
Wireless network access is no longer a “nice-to-have.” It is a critical element in all enterprise networks, whether by design, by extension, or by default. Office workers expect to have a wireless option as part of the overall network design. Mobile users extend their reach by using wireless networks wherever they are available, including in public places, in a prospect’s conference room, or at home.

Even when the policy states “No Wireless,” wireless networking is alive and well as a built-in default on most laptops. Wireless networks enable tremendous mobility, and are quickly becoming the foundation for other technologies.

WLANs gain great flexibility by the use of radio waves instead of wires to carry their communications. This freedom comes at a cost in network overhead and complexity however, as the radio medium is inherently less reliable and less secure than a wired network.

For example, 802.11 WLANs are able to transmit and receive at a variety of data rates and switch between them dynamically. They step down to a lower rate when transmission conditions are poor, and back up again when signal reception improves. They can also dynamically impose their own fragmentation, reducing packet size to reduce data loss in poor conditions.