Configuring The Demand Interface - HP ProCurve 7000dl Series Basic Management And Configuration Manual

Configuring Demand Routing for Primary ISDN Modules
Using Demand Routing for ISDN Connections
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Exit the ACL. After you have finished creating the ACL, enter exit to return
to the global configuration mode context, as shown below:
ProCurve(config-ext-nacl)# exit
ProCurve(config)#
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. (For
more information about configuring ACLs, see the Advanced Management
and Configuration Guide, Chapter 5: Applying Access Control to Router
Interfaces.)

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. You can also apply other ACLs or an access control policy
(ACP) to this interface if you want to block certain traffic from being
transmitted over the 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 a pool of
physical interfaces.
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.
Because the demand interface spoofs an up state, you can add routes to
networks reached through the dial-up connection managed by the demand
interface. The demand interface is the forwarding interface for these routes.