Changing the IS-IS level globally

1. Enter the configure terminal command to access global configuration mode.
   

   device# configure terminal

2. Enter the router isis command to enter IS-IS router configuration mode and enable IS-IS on the device.
   

   device(config)# router isis
   

3. Enter the is-type command with the level-1 parameter to globally change the IS-IS level supported from Level-1 and Level-2 to Level-1 only.
   

   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