High-Level Data Link Control
Unnumbered frames

High-Level Data Link Control

Section Title: Unnumbered frames
Table Section Text: None

Name	Command/ Response	Description	Info	C-Field Format

7	6	5	4	3	2	1	0

Set normal response mode SNRM	C	Set mode	Use 3 bit sequence number	1	0	0	P	0	0	1	1

SNRM extended SNRME	C	Set mode; extended	Use 7 bit sequence number	1	1	0	P	1	1	1	1

Set asynchronous response mode SARM	C	Set mode	Use 3 bit sequence number	0	0	0	P	1	1	1	1

SARM extended SARME	C	Set mode; extended	Use 7 bit sequence number	0	1	0	P	1	1	1	1

Set asynchronous balanced mode SABM	C	Set mode	Use 3 bit sequence number	0	0	1	P	1	1	1	1

SABM extended SABME	C	Set mode; extended	Use 7 bit sequence number	1	1	0	P	1	1	1	1

Set Mode SM	C	Set mode, generic	New in ISO 13239	0	1	1	P	0	0	1	1

Set initialization mode SIM	C	Initialize link control function in the addressed station	0	0	0	P	0	1	1	1

Request initialization mode RIM	R	Initialization needed	Request for SIM command	0	0	0	F	0	1	1	1

Disconnect DISC	C	Terminate logical link connection	Future I and S frames return DM	0	1	0	P	0	0	1	1

Request disconnect RD	R	Solicitation for DISC Command	0	1	0	F	0	0	1	1

Unnumbered acknowledgment UA	R	Acknowledge acceptance of one of the set-mode commands.	0	1	1	F	0	0	1	1

Disconnect mode DM	R	Responder in disconnected mode	Mode set required	0	0	0	F	1	1	1	1

Unnumbered information UI	C/R	Unacknowledged data	Has a payload	0	0	0	P/F	0	0	1	1

UI with header check UIH	C/R	Unacknowledged data	New in ISO 13239	0	0	0	P/F	0	0	1	1

Unnumbered poll UP	C	Used to solicit control information	0	0	1	P	0	0	1	1

Reset RSET	C	Used for recovery	Resets N(R) but not N(S)	1	0	0	P	1	1	1	1

Exchange identification XID	C/R	Used to Request/Report capabilities	1	0	1	P/F	1	1	1	1

Test TEST	C/R	Exchange identical information fields for testing	1	1	1	P/F	0	0	1	1

Frame reject FRMR	R	Report receipt of unacceptable frame	1	0	0	F	0	1	1	1

Nonreserved 0 NR0	C/R	Not standardized	For application use	0	0	0	P/F	1	0	1	1

Nonreserved 1 NR1	C/R	Not standardized	For application use	1	0	0	P/F	1	0	1	1

Nonreserved 2 NR2	C/R	Not standardized	For application use	0	1	0	P/F	1	0	1	1

Nonreserved 3 NR3	C/R	Not standardized	For application use	1	1	0	P/F	1	0	1	1

Ack connectionless, seq 0 AC0	C/R	Not part of HDLC	IEEE 802.2 LLC extension	0	1	1	P/F	0	1	1	1

Ack connectionless, seq 1 AC1	C/R	Not part of HDLC	IEEE 802.2 LLC extension	1	1	1	P/F	0	1	1	1

Configure for test CFGR	C/R	Not part of HDLC	Was part of SDLC	1	1	0	P/F	0	1	1	1

Beacon BCN	R	Not part of HDLC	Was part of SDLC	1	1	1	F	1	1	1	1

Sentence(s)

The SM command (an ISO 13239) is a generic "set mode" command.
The SM command (an ISO 13239 addition) is a generic "set mode" command.
The SM ISO 13239 is a generic "set mode" with command.

final_sentence: The SM command (an ISO 13239) is a generic "set mode" command.
final_sentence: The SM command (an ISO 13239 addition) is a generic "set mode" command.
final_sentence: The SM ISO 13239 is a generic "set mode" with command.