PPP was originally designed as an encapsulation protocol for the transmission of two IP traffic between peer configuration. In the TCP-IP protocol suite which is (a second layer in the OSI model) to a data link layer protocol connection on synchronous modulation, the former replace the second layer of non-standard protocol, i.e. SLIP. In addition to IP PPP may also transmit other protocols, including DECnet and Novell's Internet Packet Exchange (IPX).
PPP consists of the following components:
Package: A package multi-protocol datagrams. PPP encapsulation provided by different network layer protocols simultaneously multiplexing unified link. (People) PPP package carefully designed so that it retains compatibility with commonly used hardware support.
link control protocol: For over a very wide use environment can easily enough, PPP provides the LCP. LCP is used to automatically agree upon the encapsulation format options, handle packet size change detection looped-back link and other common configuration errors, and terminate the link. Other optional devices are provided: the authentication decision means peer link identity, and link failure or link capabilities normal circumstances.
Network Control Protocol: an extended link control protocol for establishing, configuring, and testing a data link connection management.
configuration: so that PPP link is easily configured through a link control protocol. The control mechanism is also applicable to other protocols, such as Network Control Protocol (NCPs)
In order to establish point to point link, each end of the PPP link must first send LCP packets to configure and test the data link. After the link is established, LCP optional equipment can be certified. Then, PPP must send NCP packets to choose and configure one or more network layer protocols. Once each of the chosen network-layer protocols are set well, datagrams from each network layer protocol can be sent over the connected road.
The link will remain configured for communications until explicit LCP and NCP close the link, or when some external event occurs (an inactivity timer expires or network administrator put one's oar in).