Configuring authentication on an IS-IS interface

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 auth-mode command with the md5 and level-2 parameters to configure MD5 authentication for Level 2 packets for the IS-IS interface.
   

   device(conf-if-eth-1/2)# isis auth-mode MD5 level-2
   

4. Enter the isis auth-key command with the level-2 parameter, specifying an authentication password, to configure an authentication key for Level 2 packets for the IS-IS interface.
   

   device(conf-if-eth-1/2)# isis auth-key level-2 mykey
   

5. Enter the isis auth-check disable command with the level-1 parameter to temporarily disable authentication checking for Level 1 and Level 2 packets for the IS-IS interface.
   

   device(conf-if-eth-1/2)# isis auth-check level-1 disable
   

The following example configures IS-IS authentication mode, an IS-IS authentication key and temporarily disables IS-IS authentication checking for a specified IS-IS interface.

device# configure terminal
device(config)# interface ethernet 1/2
device(conf-if-eth-1/2)# isis auth-mode MD5 level-2
device(conf-if-eth-1/2)# isis auth-key level-2 mykey
device(conf-if-eth-1/2)# isis auth-check level-1 disable