FDDI Frames

Token

Access permission is granted by the 3-bytes token frame (starting delimiter, access control, ending delimiter). There is no token bit as with token-ring (IEEE 802.5).

Access Control (1 byte) (Token-Ring)

Data Frame

An adpater holding the token is allowed to transmit a frame; it strips the token off the ring and transmits a data frame. There is no access control field in FDDI frames. There may be MAC frames (station management [SMT] data) or LLC frames (user data).