The Point-to-Point Protocol (PPP) is a data link layer (Layer 2) communication protocol designed to establish a direct connection between two network nodes, such as routers or computers, over a serial or point-to-point link. PPP is widely recognized for its role in enabling dial-up internet access and continues to be used in various network types, including DSL and VPN connections.
PPP can encapsulate and transport multiple network layer protocols, such as IP, IPX, and AppleTalk, making it highly versatile for different network environments. It includes mechanisms for error detection and correction to ensure reliable data transmission. PPP supports several authentication methods, including Password Authentication Protocol (PAP), Challenge Handshake Authentication Protocol (CHAP), and Extensible Authentication Protocol (EAP), offering varying levels of security for verifying the identity of connected devices. PPP uses the Link Control Protocol (LCP) to establish, configure, test, and manage the data link connection. NNCPs are used to negotiate and configure network layer protocols that will be carried over the PPP link, such as IPCP for IP traffic. PPP can compress data for faster transmission and combine multiple physical links into a single logical link to increase bandwidth.