Cisco IOS Cookbook, 2nd Edition

Using Dialer Watch

Problem

You want to use Cisco’s Dialer Watch feature to trigger dial backup.

Solution

The Dialer Watch feature allows the router to track a particular destination IP address in its routing table. If all of the tracked IP addresses disappear from the routing table, the router automatically triggers the dial backup connection:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#interface BRI0/0
Router1(config-if)#ip address 10.1.99.55 255.255.255.0
Router1(config-if)#encapsulation ppp
Router1(config-if)#dialer map ip 10.1.1.0 name dialhost broadcast 95551212
Router1(config-if)#dialer map ip 10.2.0.0 name dialhost broadcast 95551212
Router1(config-if)#dialer map ip 10.1.99.1 name dialhost broadcast 95551212
Router1(config-if)#dialer load-threshold 50 either
Router1(config-if)#dialer watch-group 1
Router1(config-if)#dialer-group 1
Router1(config-if)#isdn switch-type basic-ni
Router1(config-if)#isdn spid1 800555123400 5551234
Router1(config-if)#isdn spid2 800555123500 5551235
Router1(config-if)#ppp authentication chap
Router1(config-if)#ppp multilink
Router1(config-if)#exit
Router1(config)#router eigrp 55
Router1(config-router)#network 10.0.0.0
Router1(config-router)#exit
Router1(config)#username dialhost password cisco
Router1(config)#access-list 101 deny eigrp any any
Router1(config)#access-list 101 permit ip any any
Router1(config)#dialer-list 1 protocol ip list 101
Router1(config)#dialer watch-list 1 ip 10.2.0.0 ...