Point-to-Point Protocol (PPP)

The Point-to-Point Protocol (PPP) provides IP networking capability over serial line interfaces like those provided by modems.

You can think of PPP as a slow speed analog of Ethernet. Just as two computers can be networked by an Ethernet cable, they can be networked by modems and PPP.

In both cases the machines communicate with each other using peer-to-peer or client/server applications that run over high-level protocols such as TCP/IP. PPP and high-speed, full-duplex modems allow sophisticated services and applications, such as NFS, rlogin, ftp, and remote X11 clients, to run over public switched telephone networks (PSTN).

You activate a PPP connection when you execute any command that causes a message to be put onto the network. Typically this happens when you change to a remote directory in an NFS file system, rlogin to a remote machine, copy a remote file (either by rcp or ftp), or do any other operation that involves a remote system.

Refer to Chapter 6, Configuring for Point-to-Point Protocol Connections for more information about PPP configuration.