The tasks in Chapter 32, Setting Up a Leased-Line PPP Link (Tasks) show how to implement the goal of a medium-sized organization (LocalCorp) to provide Internet access for its employees. Currently, the employees' computers are connected on a private corporate intranet.
LocalCorp requires speedy transactions and access to the many resources on the Internet. The organization signs a contract with Far ISP, a service provider, which allows LocalCorp to set up its own leased line to Far ISP. Then, LocalCorp leases a T1 line from Phone East, a telephone company. Phone East puts in the leased line between LocalCorp and Far ISP. Then, Phone East provides a CSU/DSU that is already configured to Local Corp.
LocalCorp has set up a system as a gateway router, which forwards packets over the leased line to hosts on the Internet.
Far ISP also has set up a peer as a router to which leased lines from customers are attached.
In the figure, a router is set up for PPP at LocalCorp. The router connects to the corporate intranet through its hme0 interface. The second connection is through the machine's HSI/S interface (hih1) to the CSU/DSU digital unit. The CSU/DSU then connects to the installed leased line. The administrator at LocalCorp configures the HSI/S interface and PPP files. The administrator then types /etc/init.d/pppd to initiate the link between LocalCorp and FarISP.