An authentication password can be configured using the Hashed Message Authentication codes - Message Digest 5 (HMAC-MD5) algorithm, in conformance with RFC 3567 - Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication.
IS-IS authentication checking is enabled by default. When transitioning from one authentication mode to another, changing the authentication mode can cause packets to drop because only some of the routers have been reconfigured. During such a transition, it can be useful to disable IS-IS authentication checking temporarily until all devices are reconfigured and the network is stable.
Authentication can be configured globally or for a specified interface.
To configure IS-IS authentication globally you must perform the following tasks:
To configure IS-IS authentication on a specified interface, you must perform the following tasks: