You can use a route map to configure the device to advertise a default route to all neighboring ISs. The following task enables the advertisement of a default route if the route map “myroutemap” is satisfied.
The route-map “myroutemap” must already be configured.
device# configure terminal
device(config)# router isis
device(config-isis-router)# address-family ipv4 unicast
device(config-router-isis-ipv4u)# default-information-originate route-map myroutemap
The following example enables the advertisement of a default route if the route map “myroutemap” is satisfied.
device# configure terminal device(config)# router isis device(config-isis-router)# address-family ipv4 unicast device(config-router-isis-ipv4u)# default-information-originate route-map myroutemap