Point-to-Point Protocol (PPP)

Point-to-Point Protocol (PPP) is a layer two encapsulation for serial and dial-up connections. PPP can support authentication via various mechanisms, including:

• Password Authentication Protocol (PAP)
• Challenge Handshake Authentication Protocol (CHAP)
• Extensible Authenication Protocol (EAP)

PPP is roughly based on the earlier High Level Data Link Protocol (HDLC). On Cisco networks, HDLC is the default serial encapsulation. PPP however can be selected instead for its features or for its ability to communicate with non-Cisco devices.

An additional standard, called Multilink PPP (MP) allows for bandwidth aggregation over multiple links.

PPP is standardized in RFC 1968.

References:

http://technet.microsoft.com/en-us/library/cc768082.aspx

http://www.tcpipguide.com/free/t_PointtoPointProtocolPPP.htm

http://docwiki.cisco.com/wiki/Point-to-Point_Protocol