Point-to-Point protocol (PPP) is used to implement TCP/IP over point-to-point connections. It has the basic function of encapsulating Network Layer (Layer 3) protocol information over point-to-point links. PPP uses its own framing method which allows encapsulation of any Layer 3 protocol. Because PPP uses a point-to-point structure, no mapping of protocol addresses is required. PPP utilizes the Link Control Protocol (LCP) to communicate between a PPP client and host.
LCP tests the link between client and PPP host and specifies PPP client configuration. PPP has several capabilities that makes it adaptable to various set-ups, including:
- Multiplexing of network layer protocols
- Link configuration
- Link quality testing
- Authentication
- Header compression
- Error detection
- Link parameter negotiation
For authentication, PPP has a number of options, including:
- Password Authentication Protocol (PAP)
- Shiva Password Authentication Protocol (SPAP)
- Challenge Handshake Authentication Protocol (CHAP)
- Extensible Authentication Protocol (EAP)
These two protocols offer varying levels of protection. Both require an established username and password. This can be done on the router or on a TACACS or RADIUS authentication server.
