Wireless/Redundant Edge Services xl Module Management and Configuration Guide WS.02.xx and greater

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Introduction
Radio Ports
Many countries require support for 802.11h as a condition to using certain
802.11a channels. The countries operate military radar on those channels;
With 802.11h, the private radios to share the channels without interfering with
the military.
The second radio on the RP 220 and on the RP 230 supports 802.11a.
802.11 Frames
In addition to Physical Layer standards, 802.11 defines Data Link Layer
standards. 802.11 frame types include:
■ control frames, which wireless devices use to reserve the shared medium
■ management frames, which regulate communications between stations
and RPs and include:
• beacon frames, which the RP radio uses to announce itself to wireless
stations and which will be discussed in more detail in “Beaconing” on
page 1-60
• authentication frames, which wireless devices use to ensure that they
are connecting to the correct peer
• association frames, which stations use to negotiate the wireless con-
nection to an RP
A station cannot send or receive data until it associates to an RP.
■ data frames, which encapsulate all the higher layer packets the wireless
connection is intended to carry (for example, a data frame might include
an HTTP request for a Web page)
BSS
A BSS is the set of wireless stations controlled by a single coordination
function as well as the RP to which they connect. In other words, the BSS
consists of all stations that share the same medium (the radio signal broadcast
by an RP) to transmit and receive data. (See Figure 1-18.)