Changing the IS-IS level on an IS-IS interface

If you change the IS-IS type on an individual interface, the type you specify must also be specified globally. For example, if you globally set the type to Level 2 only, you cannot set the type on an individual interface to Level 1. The setting is accepted but does not take effect.
  1. Enter the configure terminal command to access global configuration mode.
    device# configure terminal
  2. Enter the interface ethernet command and specify an interface.
    device(config)# interface ethernet 1/2
    
  3. Enter the isis circut-type command with the level-1 parameter to configure a Level 1 adjacency for the interface.
     
    device(config-if-e1000-1/2)# isis circut-type level-1
    
    device(conf-if-eth-1/2)# isis circut-type level-1
    

The following example configures a Level 1 adjacency on an IS-IS Ethernet interface.

device# configure terminal
device(config)# interface ethernet 1/2
device(conf-if-eth-1/2)# isis circut-type level-1