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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Network Interface Layer (OSI Data Link Layer) Protocols            9  TCP/IP Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP)                 9  Point-to-Point Protocol (PPP)                      9  PPP Fundamentals and Operation

PPP Fundamentals and Operation 1 2 3 PPP Components and General Operation

PPP General Function and Architecture

PPP is a connection-oriented protocol that enables layer two links over a variety of different physical layer connections. It is supported on both synchronous and asynchronous lines, and can operate in half-duplex or full-duplex mode. It was designed to carry IP traffic but is general enough to allow any type of network layer datagram to be sent over a PPP connection. As its name implies, it is for point-to-point connections between exactly two devices, and assumes that frames are sent and received in the same order.

PPP fits into the Network Interface layer (Link Layer) in the TCP/IP model, as shown in Figure 23. The operation of PPP follows a specific sequence described in the general operation topic, including a multi-step link establishment phase that may include optional authentication.

Figure 23: PPP Location in TCP/IP Architecture

PPP acts as the interface between the Internet Protocol and a physical link such as a serial line or dial-up networking connection. This corresponds to layer two in the OSI Reference Model.

PPP Fundamentals and Operation 1 2 3 PPP Components and General Operation

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