An FDDI frame consists of an 8-bytepreamble( PA) as synchronization bit sequence, the one- byte starting delimiter( SD) for marking the header, and the frame control( FC).
The Frame Control identifies the frame for the transmission of data, tokens, management information or for error recovery.
The frame control is followed by the 6 byte destination address and the source address of the same length. This is followed by the 4,472 byte long Data field, the 4 byte long FCS field for error detection, followed by the Ending Delimiter( ED, 4 bits) which identifies the end of the frame and the Frame Status field( FS, 12 bits). Via the Frame Status (FS) the receiver can distinguish whether an error was detected, the destination address was detected or a frame was copied.