The value of the object tmnxIsisAuthKey specifies the authentication key string used to verify the authenticity of packets sent by neighboring routers on an IS-IS interface. For authentication to succeed both the authentication key and the authentication type defined by the object tmnxIsisAuthType must match. If tmnxIsisAuthType is set to 'password', tmnxIsisAuthKey can include any ASCII character. Authentication can be configured globally and applied to all ISIS levels or it can be configured on a per level basis; the most specific value is used. When read, tmnxIsisAuthKey always returns an Octet String of length zero.