interface dialer 1
desc connection to local distribution router
ip address <ip address> <subnet mask>
encapsulation ppp
ppp authentication chap
ppp chap hostname isdn
ppp remote-name isdn
dialer string <local distribution router number>
dialer watch-group 1
dialer-group 1
ip ospf network point-to-multipoint
ip ospf demand-circuit
dialer idle-timeout 20 inbound

interface dialer 2
desc connection to nearby distribution router
ip address <ip address> <subnet mask>
encapsulation ppp
ppp authentication chap
ppp chap hostname isdn
ppp remote-name isdn
dialer string <nearby distribution router number>
dialer watch-group 2
dialer-group 1
ip ospf network point-to-multipoint
ip ospf demand-circuit
dialer idle-timeout 20 inbound

interface dialer 3
desc connection to core router
ip address <ip address> <subnet mask>
encapsulation ppp
ppp authentication chap
ppp chap hostname isdn
ppp remote-name isdn
dialer string <core router number>
dialer watch-group 3
dialer-group 1
ip ospf network point-to-multipoint
ip ospf demand-circuit
dialer idle-timeout 20 inbound

dialer watch-list 1 ip <common ip address> <subnet mask>

dialer watch-list 2 ip <common ip address> <subnet mask>
dialer watch-list 2 delay connect 40

dialer watch-list 3 ip <common ip address> <subnet mask>
dialer watch-list 3 delay connect 80