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Station States and Corresponding Frame Types
Apr 30,2007 00:00
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Station States and Corresponding Frame Types The state existing between a source and destination station (see Figure 3.10) governs which IEEE 802.11 frame types the two stations can exchange. The following types of functions can occur within each class of frame: Class 1 Frames • Control frames Request to send (RTS) Clear to send (CTS) Acknowledgment (ACK) Contention-free (CF) • Management frames Probe request/response Beacon Authentication Deauthentication Announcement traffic indication message (ATIM) • Data frames Class 2 Frames • Management Frames Association request/response Reassociation request/response Disassociation Class 3 Frames • Data frames Management frames Deauthentication Control frames Power Save Poll To keep track of station state, each station maintains the following two state variables: • Authentication state Has values of unauthenticated and authenticated. • Association state Has values of unassociated and associated. As mentioned in this chapter, the 802.11 wireless LAN standard certainly has benefits that an organization should consider when selecting components that provide LAN mobility. IEEE 802 is a solid family of standards that will provide much greater multiple-level interoperability than proprietary systems. The 802.11 standard has the backing of IEEE, having an excellent track record of developing long-lasting standards, such as IEEE 802.3 (ethernet) and IEEE 802.5 (token ring). Chapters 4 and 5 cover the details of the 802.11 standards |