It is used to share information about other directly connected Cisco equipment, such as the operating system version and IP address.
By default, CDP announcements are sent every 60 seconds on interfaces that support Subnetwork Access Protocol (SNAP) headers, including Ethernet, Frame Relay and Asynchronous Transfer Mode (ATM).
[2] The information contained in CDP announcements varies by the type of device and the version of the operating system running on it.
Hewlett-Packard removed support for transmitting CDP from HP Procurve products shipped after February 2006 and all future software upgrades.
[citation needed] CDP was the abbreviation used by Cabletron who wrote the RFC 2641 for the discovery protocol.