Configuring The Demand Interface - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Configuring Backup WAN Connections
Configuring Demand Routing for Backup Connections
3-20
Examples. For example, if you want any traffic to the far-end network
192.168.115.0 /24 to trigger the dial-up connection, you would enter:
ProCurve(config-ext-nacl)# permit ip any 192.168.115.0 0.0.0.255
If you want any outbound traffic from a particular network segment to trigger
a dial-up connection, use wildcard bits to specify that network as the source.
For example, enter:
ProCurve(config-ext-nacl)# permit ip 192.168.1.0 0.0.0.255 any
Implicit "Deny Any" for ACL. Each ACL includes an implicit "deny any"
entry at the end of the list. If a packet does not match any entry in the ACL
you create, it matches the implicit "deny any" entry.
After you have finished creating the ACL, enter exit to return to the global
configuration mode context.
After you create the ACL, you must apply it to the demand interface. In fact,
the ACL will have no effect until you apply it to the demand interface.

Configuring the Demand Interface

You must create a demand interface for each router to which the ProCurve
Secure Router will connect through a dial-up connection. The demand inter-
face provides the Data Link Layer for the physical dial-up interface.
Like other logical interfaces such as Frame Relay or PPP, the demand interface
controls the logical functions for the WAN connection. In many ways, you
configure the demand interface as you do any other logical interface. For
example, you assign the demand interface an IP address. From this interface,
you apply the ACL that defines the interesting traffic that triggers the dial-up
WAN connection.
The demand interface is different from other logical interfaces, however. For
one thing, the demand interface is not bound to a specific physical interface
or interfaces. Instead, the demand interface is associated with the pool of dial-
up interfaces used for backup.
The demand interface must also handle its status differently: it must always
be up, whether or not the physical dial-up interface associated with the
demand interface is up. Because the demand interface cannot actually be up
if the Physical Layer is down, it "spoofs" an up state. As a result, the demand
interface can be listed as a directly connected interface in the router's routing
table, even when the dial-up interface is not in use.