By default, a device can operate as both a Level 1 and Level 2 router. This task globally changes the level supported from Level 1 and Level 2 to Level 1 only.
device# configure terminal
device(config)# router isis
device(config-isis-router)# is-type level-1
The following example globally changes the IS-IS level supported from Level-1 and Level-2 to Level-1 only.
device# configure terminal device(config)# router isis device(config-isis-router)# is-type level-1