PPP

A Link Layer protocol based on a Link Control Protocol (LCP) and a Network Control Protocol (NCP). The LCP is responsible for setting up a link between two computers over a circuit-switched telephone connection, and for resolving any issues of authentication.The NCP negotiates any parameters specific to the Network Layer.The Internet Protocol Control Protocol (IPCP), for example, is used when the Internet Protocol (IP) is employed at the Network Layer. PPPdefines a sequence of characters that frame Internet Protocol (IP) datagrams on a serial line. In that respect, it is much like the Serial Line Internet Protocol (SLIP). However, PPP also supports a variety of authentication and encryption methods for enhanced security and a variety of compression options that can eliminate unused or redundant data in the headers of long sequences of packets in a transmission stream. PPP incorporates an error correction mechanism in the form of a cyclic redundancy check (CRC). PPP supports multiple native machine and network protocols, and supports subnet routing. PPP is defined in RFC 1661, and numerous other RFCs define various PPP implementations. Internet service providers (ISPs) commonly use PPP to support dial-up customers. Multilink PPP allows the combination of multiple links to increase bandwidth between two nodes. PPP over Ethernet (PPPoE) encapsulates PPP in Ethernet frames and is commonly used by ISPs to support Asymmetric Digital Subscriber Line (ADSL) customers. PPP over ATM (PPPoATM) is sometimes used by ISPs to support customers with ATM-based ADSL routers. See also ADSL, ATM, authentication, CRC, datagram, dial-up, encryption, Ethernet, IP, ISP, LCP, Link Layer, Multilink PPP, NCP, packet, PPPoA, PPPoE, protocol, router, routing, serial, and subnet.