3Com AccessBuilder 500 User Manual - page 90
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Numbered and Unnumbered Links
When routing and using the AccessBuilder 500’s FastConnect protocol
over ISDN links as opposed to PPP, you have the option of using
numbered or unnumbered links.
A numbered link requires a valid IP address to be configured for both
ports connected to each end of the link. The IP address used must be
for a different subnet or network than that used by either LAN at each
end of the link. An example is shown in
Figure A-6
. In this example, the
Local Site uses the network address 191.000.100.xxx on its LAN. The
remote site uses the network address 191.000.200 on its LAN and the
link uses 191.000.300.
Figure A-6
Example Of A Numbered Link
By default the ISDN port has an IP address of 10.0.0.1. This is set to allow
remote Telnet connections to the unit to enable configuration but must
be changed when configuring the unit to allow correct operation. If you
use the
Quick Configuration
(
QC
) option to configure the unit to operate
over ISDN, the Port IP Address is set to unnumbered.
In most instances you should use unnumbered links. This is easier to
configure and does not use network addresses which may be in short
supply.