(Link Access Protocol-D): The data link layer 2 protocol that manages the exchange of information to the ISDN network. LAPD is defined in Q.921.

Link Access Protocol - D Channel. Standard protocol for ISDN that defines the signalling in the "D" channel of the 192 kbps ISDN signal.

An Integrated Services Digital Network (ISDN) data link layer procedure, used for signaling and control on the D channel of an ISDN network.

See Link Access Procedures on the D Channel (LAPD).

Link Access Procedure Digital, Link Access Protocol Digital, or Link Access Process Data. Link-level protocol devised for ISDN connections.

Link Access Procedure on the D channel. ISDN data link layer protocol for the D channel. LAPD was derived from the LAPB protocol and is designed primarily to satisfy the signaling requirements of ISDN basic access. Defined by ITU-T Recommendations Q.920 and Q.921.