Networking Guide
Chapter 9, Configuring the Point-to-Point Protocol (PPP)

PPP support for smart serial port devices

PPP support for smart serial port devices

SCO PPP can also support third-party PPP STREAMS stacks for use with smart asynchronous serial port devices that are capable of performing packetization and framing in hardware. Using smart serial port devices has two performance benefits:

To support on-card framing, a third-party PPP STREAMS stack can be defined in the file /etc/pppstack (see pppstack(SFF)). Such a stack consists of: If /etc/pppstack specifies the driver and one or more asynchronous modules for a third-party smart serial port device, pppd opens the driver and pushes the specified modules on top of it.

If /etc/pppstack does not exist, the PPP daemon configures the default SCO-supplied PPP stack. Figure 9-2 shows how the SCO and third-party PPP stacks are configured below the PPP driver. 

Figure 9-2 SCO and third-party PPP stacks

See ``Configuring PPP asynchronous serial driver support'' for instructions on how to configure PPP to use a third-party smart serial port device.