HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual page 104

Configuring Backup WAN Connections
Configuring Demand Routing for Backup Connections
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Including in or out is optional. By default, the ProCurve Secure Router uses
the ACL you specify to check both incoming and outgoing traffic. If you do
not specify a direction, outbound traffic is matched to the specified ACL, and
inbound traffic is matched to the reverse of the ACL.
Outbound interesting traffic triggers the demand interface to initiate the dial-
up link. Outbound interesting traffic also resets the idle timer on an active link.
(The idle timer determines how long the ISDN connection can remain up if no
traffic is transmitted over it.) Inbound interesting traffic only resets the
idle timer.
If you include the in option when you enter the match-interesting command,
the ProCurve Secure Router will use the specified list to select inbound
interesting traffic. If you include the out option, the router will determine
whether the traffic outbound through the interface is interesting.
For example, if you want to apply the Backup ACL to demand 1 interface,
enter:
ProCurve(config-demand 1)# match-interesting list Backup
When you view the demand interface in the running-config, you will see two
commands, even though you entered only one. (See Figure 3-7.)
interface demand 1
match-interesting list Backup out
match-interesting reverse list Backup in
Figure 3-7. The match-interesting Command as Displayed in the Running-Config
Entering the following two commands would accomplish the same thing as
entering match-interesting list Backup:
ProCurve(config-demand 1)# match-interesting list Backup out
ProCurve(config-demand 1)# match-interesting reverse list Backup in
After you configure demand routing, you should monitor usage of the dial-up
connection to determine if you have correctly configured the ACL to select
interesting traffic. To avoid any problems when the bill for the dial-up connec-
tion arrives, ensure that the dial-up connection is being triggered only when
you want it to be. To minimize costs, you may need to change the ACL by
further limiting the traffic that triggers the connection.