Parts of a Leased-Line PPP Link

See the following figure.

Figure 15–3 Basic Leased-Line Configuration

The leased-line link contains the following parts:

• Two peers, each peer at one end of the link. Each peer might be a workstation or server. Often the peer functions as a router between its network or the Internet, and the opposite peer.

• Synchronous interface on each peer. Some machines that run Solaris software require you to purchase a synchronous interface card, such as HSI/P, to connect to a leased line. Other machines, such as UltraSPARC® workstations, have built-in synchronous interfaces.

• CSU/DSU synchronous digital unit on each peer, which connects the synchronous port to the leased line.

  A CSU might be built-in to the DSU, or owned by you, or leased from a provider, depending on your locale. The DSU gives the Solaris machine a standard synchronous serial interface. With Frame Relay, the Frame Relay Access Device (FRAD) performs the serial interface adaptation.

• Leased line, providing switched or unswitched digital services. Some examples are SONET/SDH, Frame Relay PVC, and T1.