http://www.rfc-editor.org/rfc/rfc1548.txt
RFC 1548: The Point-to-Point Protocol (PPP), W. Simpson1993-12-01T23:00:00-00:00This document defines the PPP organization and methodology, and the PPP encapsulation, together with an extensible option negotiation mechanism which is able to negotiate a rich assortment of configuration parameters and provides additional management functions. [STANDARDS-TRACK]