Chapter Eleven. IP in 802.11 Networks

In today's world, local area networks (LANs) are almost ubiquitous in their existence as the uniform method of data communication across various devices, including computers. Although they were initially defined to be smaller in size (typically the size of an office building or campus), LANs now may span several cities or even continents.

LANs consist of computers, servers, printers, and other devices connected through wires or physical cables that run through the premises. LANs are typically extended to new locations by drawing physical cables and creating ports for computers to access the LAN.

The addition of wireless capabilities allows LANs to be extended without the use of wires or cables, thus enabling untethered communications. This is especially useful when reconstruction may be required to lay new cables in older buildings or in hazardous areas. Thus, in one point of view, wireless versions of LANs allow current "wired" LANs to be extended to new places, and thus augment the capabilities of a LAN.

The other advantage of wireless LANs (WLANs) is their inherent mobility, as computers do not have to be attached to LAN ports using cables. The advantage adds a new dimension that allows new configurations such as wireless-only LANs. It also allows for a new set of applications and services (for example, doctors can access patient databases on site at the patient's bedside to quickly determine a course of action).