12
CONFIGURING PPP AND MP
This chapter contains information on the following topics:
■ PPP Overview
■ MP Overview
■ Configure PPP
■ Configure MP
■ Display and Debug PPP
■ Typical PPP Configuration Example
■ Typical MP Configuration Example
■ Fault Diagnosis and Troubleshooting of PPP
PPP Overview The Point-to-Point Protocol (PPP) provides a standard method for transporting
multi-protocol datagram over point-to-point links. It gains wide applications since
it can provide user authentication, support synchronous/asynchronous lines and
can be expanded easily.
PPP defines a whole set of protocols, including link control protocol (LCP), network
control protocol (NCP) and authentication protocols (PAP and CHAP). Of them:
■ Link Control Protocol is used to negotiate some parameters of the link and is
responsible for creating and maintaining the link.
■ Network Control Protocol is used to negotiate the parameters of network layer
protocol.
PPP Authentication Mode
1 PAP authentication
PAP (Password Authentication Protocol) is a 2-way handshake authentication
protocol and it transmits username and password in plain text over the Internet.
The process of PAP authentication is as follows:
The requester repeatedly sends its username/password combination across the link
until the authenticator responds with an acknowledgment or until the link is
broken. The authenticator may disconnect the link if it determines that the
username/password combination is not valid.
2 CHAP authentication
CHAP (Challenge-Handshake Authentication Protocol) is a 3-way handshake
authentication protocol. It only sends the username but not the password across
the link. The process of CHAP is as follows:
