Using Wireless LANs
Wireless LAN Overview
Devices on a wireless LAN (WLAN) transmit and receive data using radio
or infrared signals, sent through an access point (AP). WLANs function
similarly to Ethernet LANs with the access point providing connectivity to
the rest of the network as would a hub or switch. WLANs use an Institute of
Electrical and Electronics Engineers (IEEE) standard that defines the physical
and data link specifications, including the use of Media Access Control
(MAC) addresses. The same protocols (such as IP) and applications (such as
IPSec) can run over both wired and wireless LANs.
WLANs are local to a building or a campus, use customer-owned equipment,
and are not usually required to have radio frequency (RF) licenses.
Service Set Identifiers (SSID) correspond to a VLAN and can be used to
segment users. SSIDs can be broadcast by the access point, or statically
configured on the client, but the client must have the same SSID as the AP to
register with it. SSIDs are case sensitive. Clients associate with access points
as follows:
Step 1. The client sends a probe request.
Step 2. The AP sends a probe response.
Step 3. The client initiates an association to an AP. Authentication and
any other security information is sent to the AP.
Step 4. The AP accepts the association.
Step 5. The AP adds the client’s MAC address to its association table.