Frame Control (1 byte) (Token-Ring)

Protocol: Token-Ring MAC Token-Ring PCI

Field: frame control

Length: 1 byte

Contents: frame contents indicator.

The frame control field indicates the kind of data of the current PDU:

Frame Type Bits

The first two bits indicate whether its a MAC or a LLC frame.

00 = MAC Frame

01 = LLC Frame

10 = (reserved)

11 = (reserved)

Control Bits

LLC: With LLC, the control bits aren't used and set to '0000'.

MAC: With MAC frames, the control bits indicate various message types (often called 'attention code').

Attention Codes

000000 normal buffered

000001 express buffered

000010 beacon

000011 claim token

000100 ring purge

000101 active monitor present (AMP)

000110 standby monitor present (SMP)

See:

Token-Ring Vectors (Major Vectors / Subvectors)