802.11 frame
The data frame for access by WLAN stations to the network is defined in the 802.11 standard. It consists of the MAC header, the frame body and the checksum field( FCS). The MAC header has a fixed length of 30 bytes, the Frame Body data field has a variable length between 0 and 2,312 bytes, and the checksum field is 4 bytes long.
The MAC header consists of a total of seven data fields and begins with the 2- byte Frame Control( FC) data field. This is followed by the Duration/ ID data field, also 2 bytes long, in which the Association Identity or a value for updating the Network Allocation Vector( NAV) is entered. This is followed by four address fields, each 48 bits long, in which the Basic Service Set Identifier ( BSSID), the Source Address ( SA) and Destination Address ( DA), the Transmitter Address( TA) and Receiver Address( RA) are transmitted. The address structure of the MAC addresses corresponds to the standard defined in 802.
The checksum field (FCS) terminating the 802.11 frame is 4 bytes long and includes the checksum for the entire MAC header. The frame body field is not included.