Technical Terms and Definitions

LAPF - Telecommunications

LAPF , or Link Access Procedure to Frame Mode Bearer Services (FR, ISDN), is a modified LAPD standard for Frame Relay. It provides capabilities to establish and release data link connections, transfer acknowledged and unacknowledged data, flow control the transfer of data, and reinitialize the data link connection on detecting an error.

The format of the header is shown in the following illustration.

8 7 6 5 4 3 2 1

Default address field format

(2 octets)

Upper DLCI C/R EA
0
Lower DLCI FECN
(Note)
BECN
(Note)
DE
(Note)
EA
1

EA
Address field extension bit.

C/R
Command Response bit.

FECN
Forward Explicit Congestion Notification.

BECN
Backward Explicit Congestion Notification.

DLCI
Data Link Connection Identifier.

DE
Discard Eligibility indicator.