HP 7102dl - ProCurve Secure Router Configuration Manual page 111

Configure the Demand Interface as an Unnumbered Interface. To
conserve IP addresses on your network, you may want to create the demand
interface as an unnumbered interface. The demand interface will then use the
IP address of another interface. However, if the interface to which the IP
address is actually assigned goes down, the demand interface will be unavail-
able as well. Because there is little chance that a loopback interface will go
down, you may want to assign the IP address to a loopback interface.
To configure the demand interface as an unnumbered interface, enter the
following command from the demand interface configuration mode context:
Syntax: ip unnumbered <interface ID>
Valid interfaces from which the demand interface can take its address include:
Ethernet interfaces and subinterfaces
Frame Relay subinterfaces
PPP interfaces
loopback interfaces
Asynchronous Transfer Mode (ATM) subinterfaces
Spoofing. After you configure an IP address for the demand interface, its
status should change to "up (spoofing)," and it should be listed as a directly
connected interface in the routing table. To check the status of the demand
interface, enter:
ProCurve(config-demand 1)# do show interface demand 1
To view the routing table, enter:
ProCurve(config-demand 1)# do show ip route
Figure 3-6 shows a routing table that includes demand interface 1, a directly
connected interface.
C 10.2.2.0/30 is directly connected, ppp 1
C 10.3.3.0/30 is directly connected, demand 1
C 192.168.20.0/24 is directly connected, eth 0/1
Figure 3-6. A Routing Table That Includes a Demand Interface
Configuring Backup WAN Connections
Configuring Demand Routing for Backup Connections
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