PPP

PPP was designed in the 1980s as a point-to-point Internet encapsulation protocol. In addition to that, it overcomes the standards limitations on serial connectivity, including addressing, encapsulation, and multiple protocol support through Link Control Protocols (LCPs) and Network Control Protocols (NCPs). PPP includes router-to-router and host-to-host type connections over synchronous and asynchronous circuits.

The Layers

PPP offers secure access over any WAN Physical Layer interface, including asynchronous/synchronous serial, HSSI, and ISDN. It uses LCPs to negotiate and set up data-link parameters and NCPs to encapsulate multiple protocols, as illustrated in Figure 9-4.

Figure 9-4. PPP Layers

The frame structure is very similar to ISO's ...

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