A hardwired, leased-line PPP configuration involves two peers that are connected by a link. This link consists of a switched or an unswitched digital service leased from a provider. Solaris PPP 4.0 works over any full-duplex, point-to-point leased-line medium. Typically, a company rents a hardwired link from a network provider to connect to an ISP or other remote site.
See the following figure.
Figure 1-3 Basic Leased-Line Configuration
The leased-line link contains the following parts:
Synchronous interface on each peer. Some machines that run Oracle 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.
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 Oracle Solaris machine a standard synchronous serial interface. With Frame Relay, the Frame Relay Access Device (FRAD) performs the serial interface adaptation.
On most types of leased lines, peers do not actually dial each other. Rather, a company purchases a leased-line service to connect explicitly between two fixed locations. Sometimes the two peers at either end of the leased line are at different physical locations of the same company. Another scenario is a company that sets up a router on a leased line that is connected to an ISP.
Leased lines are less commonly used than dial-up links, though the hardwired links are easier to set up. Hardwired links do not require chat scripts. Authentication is often not used because both peers are known to each other when a line is leased. After the two peers initiate PPP over the link, the link stays active. A leased-line link remains active unless the line fails, or either peer explicitly terminates the link.
A peer on a leased line that runs Solaris PPP 4.0 uses most of the same configuration files that define a dial-up link.
The following process occurs to initiate communication over the leased line:
The peers read their PPP configuration files.
The peers negotiate communications parameters.
An IP link is established.