Reference Guide for the Model RT210/RT211 ISDN Routers
3-14 Configuring the Router
Operating with a Single IP Address
Many Internet service providers (ISPs) supply a single 32 bit host address to the user instead of a
netmask address. ISPs assign this address to the host PC or the workstation and do not leave an
address free for the LAN port of the router. Therefore, there is not a gateway through which the
host can send packets for routing to other networks.
To overcome this problem, the PPP path should have the host address entered in the IP
ADDR&MASK field of the path with a netmask of /0. The LAN01 path can then be assigned any
unused address on the same segment as the host, but should be entered with a netmask of /32. This
is what the host should use as the default gateway. The IP address of the router (LAN01) is never
advertised across the link. It is used only on the local network for communications between the
host and the router.
If the unit is configured through Quick Setup with a netmask of /0, the LAN01 path is
automatically assigned a value equal to the 32 bit host address + 1. The incremented LAN01
address is assigned with the assumption that this address might belong to another host allocated by
the ISP, but that communication between the two users is not required.
Caller Line Identification (CLI)
CLI can be used to give access only to those ISDN callers whose numbers have been previously
configured.
If Caller Line Identification is enabled on the ISDN line by the service provider, the ISDN number
of the calling unit is presented to the router when a call is received. If the CLI parameter on the
CONF PORT screen is set to YES, all configured paths are scanned to see whether the calling
number matches one in a path. If it does, the call is accepted. If the calling number does not match
one in a path, the call is rejected.
Obtaining Additional Bandwidth
There are two methods of making ISDN calls automatically to obtain extra bandwidth for a path:
• Minimum bandwidth
• Bandwidth on demand
These two options are set in the Con���gure Paths menu.
NGRRT210.BK Page 14 Friday, October 17, 1997 2:37 PM