Cabletron Systems CSX100 series User Manual - page 42
ISDN Router
28
You will need to define the default route for a remote router (if the target
router will be placing calls to that remote router). There can be only one
default route specified for all the remote database entries.
Note: You cannot have more than one router configured to advertise
itself as the default router. Usually, this not a problem since most
organizations have only one router. However, if you have more than one
router, be sure to choose only one router as the default router and change
the configuration of the other routers accordingly.
Source (Target) and Remote WAN IP Addresses
You may need to specify a source WAN IP address and/or a remote WAN
IP address for the WAN connection to the remote router depending on IP
address negotiation under PPP. Check with your system administrator
for details on whether the router must communicate in numbered or
unnumbered mode and what addresses are required. The three possible
scenarios are illustrated on the next page.
In unnumbered mode, neither IP address is defined on the WAN link. In
numbered mode, one IP address is defined on each end of the WAN link.
These addresses may or may not belong to the same subnetwork. They
may also be determined automatically, negotiated, or forced by the
network administrator.
The Router runs in unnumbered mode or numbered mode, determined
automatically. If unnumbered mode negotiation fails, numbered mode is
attempted using the Ethernet LAN IP address as a default source WAN
IP address. If you have specified a source WAN IP Address, unnumbered
mode negotiation is not performed; i.e., the operating mode is numbered.
If a source WAN IP address is explicitly defined, the router will not, as a
rule, accept another local address from the remote end. In numbered
mode without an explicit Source WAN IP address, this address can be
negotiated to a different value by the remote end.
If the remote router supports unnumbered mode, neither address needs to
be specified.
For numbered mode, consider the capabilities of the remote router as well
as your requirements. Specify a Source WAN IP Address if the target