Compatible Systems 5.4 - Manual (Page 162)

156 Chapter 10 - WAN Link Protocols
> Link Type
This pull-down menu determines how the router will maintain the WAN link,
and sets the low-level communications protocol which will be used on the
line connected to this interface.
• If On Demand PPP Link is selected, the router will treat the line
connected to this interface as an intermittent “on-demand” connection
which may require dialing commands to be issued. The router will use
the Point-to-Point protocol to establish communications with the system
at the other end of the line. Whether a connection can be initiated by this
router, another router (or remote node client), or both, can be set using
the Allow Dial Out and Allow Dial In checkboxes (as explained later in
this chapter).
• If Dedicated PPP Link is selected, the router will treat the line
connected to this interface as a connection which is always available
regardless of traffic activity. The router will use the Point-to-Point
protocol to establish communications with the system at the other end of
the line.
• If Frame Relay Link is selected, the router will treat the line connected
to this interface as a connection which is available regardless of traffic
activity. The router will use the Frame Relay protocol to establish
communications with the system (typically a Frame Relay switch) at the
other end of the line.
v Note: For On Demand PPP Link operation over RS-232C DIN-8 inter-
faces, Compatible Systems routers require that your communications device
(modem, CSU/DSU, TA, etc.) be set to raise the DCD (data carrier detect)
and/or DSR (data set ready) line when a connection is established, and drop
it when the connection is terminated.
v Note: If an interface is set to On Demand PPP Link, there are certain
maintenance packets for each protocol (IP, IPX, etc.) which will not cause an
inactive connection to be dialed. This is a security measure that keeps
intruders out and allows on-demand links to be useful.
v Note: The push buttons at the bottom of this dialog box will change
depending on the choice you make for this pulldown.
Failover Type
WAN ports can be set to divert their traffic to a secondary port (known as
“failing over”) if a line problem is detected. This pull-down menu determines
the failover mode for this port.
Ports set for PPP operation will fail over if the PPP echo protocol determines
that the line is down. Ports set for Frame Relay operation will fail over if the