PPP/Multilink PPP

The Point-to-Point Protocol (PPP), as described in RFC 1661, provides an encapsulation protocol for transporting network layer traffic over point-to-point links, such as synchronous serial or Integrated Services Digital Network (ISDN). Multilink PPP (MLP), as defined in RFC 1990, is a variant of PPP used to aggregate multiple WAN links into one logical channel for the transport of traffic. It enables the load-balancing of traffic from different links and allows some level of redundancy in case of a line failure on a single link.

The Cisco implementation follows standards to provide the following functionality: High-Level Data Link Control (HDLC) protocol for encapsulating datagrams; an extensible Link Control Protocol (LCP) to establish, configure, and test the data link connection; and Network Control Protocols (NCPs) to negotiate configuration parameters.