Deploying Secure 802.11 Wireless Networks with Microsoft Windows

802.11 Wireless LAN Components

IEEE 802.11 wireless LAN networking consists of the following components:

• Stations

• Wireless APs

• Ports

These components are shown in Figure 1-3.

Figure 1-3. The components of 802.11 wireless LAN networking.

Stations

A station (STA) is a computing device that is equipped with a wireless LAN network adapter. A personal computer equipped with a wireless LAN network adapter is known as a wireless client. Wireless clients can communicate with each other either directly or through a wireless AP. An STA can be stationary or mobile.

Wireless Access Points

A wireless AP is a networking device equipped with a wireless LAN network adapter that acts as a peripheral bridge device to extend a traditional wired network to include STAs. An AP contains the following:

• At least one interface that connects the AP to an existing wired network (such as an Ethernet backbone).

• Radio equipment with which it creates wireless connections with wireless clients.

• IEEE 802.1D bridging software, so it can act as a transparent bridge between the wireless and wired networks.

The wireless AP is similar to a cellular phone network s base station wireless clients communicate with the wired network and other wireless clients through the wireless AP, and wireless APs are stationary.

Ports

A port is a logical channel of a device that supports a single point-to-point connection. For IEEE 802.11, a port is an association a logical entity over which a single wireless connection is made. A typical wireless client or wireless AP has multiple ports and can support multiple simultaneous wireless connections.

The logical connection between a port on the wireless client and a port on a wireless AP is a point-to-point bridged LAN segment, similar to an Ethernet-based network client connected to an Ethernet switch. All frames sent from a wireless client whether unicast, multicast, or broadcast are sent on the point-to-point LAN segment between the wireless client and the wireless AP. For frames sent by the wireless AP to wireless clients, unicast frames are sent on the point-to-point LAN segment, and multicast and broadcast frames are sent to all connected wireless clients at the same time.