device# configure terminal
device(config)# router isis
device(config-isis-router)# address-family ipv4 unicast
device(config-router-isis-ipv4u)# summary-address 10.1.0.0 255.255.0.0 level-1 level-2
The following example configures a summary address of 10.1.0.0 with a mask of 255.255.0.0 for Level 1 and Level 2 routes.
device# configure terminal device(config)# router isis device(config-isis-router)# address-family ipv4 unicast device(config-router-isis-ipv4u)# summary-address 10.1.0.0 255.255.0.0 level-1 level-2