C WIRELESS LAN B ASICSThis appendix provides basic information on wireless local networks.Other terms related to wireless networks that are not included in thisappendix can be found in the Glossary starting on page 143.Wireless Modes There are two modes in which wireless local networks can operate:■ Ad hoc mode■ Infrastructure modeAd Hoc Mode Ad hoc mode does not require an Access Point or a wired local network.Wireless stations (for example, notebook with wireless cards installed) cancommunicate directly with each other.Infrastructure Mode In infrastructure mode, one or more Access Points are used to connectwireless stations to a wired local network. The wireless stations that areassociated with the Access Point can access all resources on the localnetwork.Access Points can only function in infrastructure mode and cancommunicate only with wireless stations that are set to infrastructuremode.SSID/ESSIDBSS/SSID A group of wireless stations and a single Access Point, all using the sameID (SSID), form a Basic Service Set (BSS).Using the same SSID is essential. Wireless devices that use different SSIDsmay not be able to communicate with each other. However, some AccessPoints allow connections from wireless stations that have their SSID set toany or whose SSID is blank (null).
