Control (1-2 bytes) (HDLC)

Protocol: HDLC HDLC PCI

Field: control

Length: 1-2 bytes

Contents: HDLC control data (data flow control etc).

HDLC and LLC both use the same control field codes:

Control (1-2 bytes) (LLC)

HDLC uses 3-bits or 7-bits sequence numbers.

Lenght of Control = 1 byte: 3-bits sequence numbers (modulo 8)

Lenght of Control = 2 bytes: 7-bits sequence numbers (modulo 128)

HDLC Operation