LAC

L2TP access concentrator. A Point-to-Point Protocol (PPP) access server with Layer 2 Tunneling Protocol (L2TP) capabilities that provides the physical connection (usually a modem or ISDN port) between the dial-in user and the outsourcer. On a PortMaster 4, a LAC can be a single line board or the entire device.

See also L2TP, LNS, and PPP.