Parts of a Leased-Line PPP Link (System Administration Guide: Resource Management and Network Services)

System Administration Guide: Resource Management and Network Services

Parts of a Leased-Line PPP Link

Figure 29–3 Basic Leased-Line Configuration

The parts of the leased-line link include:

Two peers, one at each 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/S, to connect to a leased line. Other machines, such as UltraSPARC^TM 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.

Note –

SONET is called an octet synchronous link. PPP uses a framing mechanism similar to asynchronous framing over a SONET line. PPP does not use the expected bit-synchronous protocol.