This read-write enumerated integer sets CDP's operating mode for the entire device: enable(1) to always run CDP, disable(2) to turn it off entirely, or autoEnable(3), the recommended default, in which the device listens passively and only begins sending CDP messages upon receiving them, matching the version and type it heard. An administrator configures this to control whether the device participates in neighbor discovery at all, and whether it does so proactively or only reactively. For example, on a security-sensitive device where advertising topology information is undesirable, the admin sets this object to disable(2) to prevent the device from sending or processing any CDP messages.