* The Point-to-Point Protocol (PPP) was designed to provide a dedicated line for users who need Internet access via a telephone line or a cable TV connection.
* A PPP connection goes through these phases: idle, establishing, authenticating (optional), networking, and terminating.
* At the data link layer, PPP employs a version of HDLC.
* The Link Control Protocol (LCP) is responsible for establishing, maintaining, configuring, and terminating links.
* Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) are two protocols used for authentication in PPP.
* PAP is a two-step process. The user sends authentication identification and a password. The system determines the validity of the information sent.
* CHAP is a three-step process. The system sends a value to the user. The user manipulates the value and sends its result. The system verifies the result.
* Network Control Protocol (NCP) is a set of protocols to allow the encapsulation of data coming from network layer protocols; each set is specific for a network layer protocol that requires the services of PPP.
* Internetwork Protocol Control Protocol (IPCP), an NCP protocol, establishes and terminates a network layer connection for IP packets.
