Editing LAPB (section)

==Protocol commands and responses==
{| class="wikitable"
|-
!Type
!Commands
!Response
!Info
|-
|Supervisory
|RR
|RR
|acknowledges the reception of a frame and indicates that the device is ready to receive the next one in the sequence
|-
|
|RNR
|RNR
|acknowledges a received frame but it indicates that it cannot receive any more I-frames because it is still busy
|-
|
|REJ
|REJ
|requests the retransmission of I-frames, the packet contains the error frame so that the DTE will retransmit all packets since the error frame
|-
|
|
|SREJ
|requests the retransmission of selected I-frames, the packet contains the specific frames that the DTE will retransmit (not used for modulo 8, optional for modulo 128, mandatory for modulo 32768)
|-
|Unnumbered
|SABM
|UA
|establish the DTE to DCE link in Normal (Basic) mode (modulo 8)
|-
|
|SABME
|UA
|establish the DTE to DCE link in Extended mode (modulo 128)
|-
|
|SM
|UA
|establish the DTE to DCE link in Super mode (modulo 32768)
|-
|
|DISC
|DM
|terminates the link
|-
|
|
|FRMR
|Frame Reject, which reports an error condition
|-
|Information
|I
|
|
|}

{| class="wikitable"
|-
!Command frame sent with P = 1
!Response frame returned with F = 1
!Info
|-
|SABM, SABME, SM
|UA, DM
|
|-
|I-frame
|RR, RNR, REJ, SREJ
|
|-
|I-frame
|FRMR
|
|-
|RR, RNR, REJ
|RR, RNR, REJ, SREJ
|
|-
|FRMR
|FRMR
|
|-
|DISC
|UA, DM
|
|}