Cisco Discovery Protocol (CDP) is a device-discovery protocol that runs on all Cisco network equipment. Each device sends identifying messages to a multicast address, and each device monitors the messages sent by other devices. Information in CDP packets is used in network management software such as CiscoWorks2000. Use the CDP page to adjust the device's CDP settings.

CDP Properties

Cisco Discovery Protocol (CDP)

Select Disabled to disable CDP on the device; select Enabled to enable CDP on the device. CDP is enabled by default.

Packet Hold Time (optional)

The number of seconds other CDP-enabled devices should consider the CDP information valid. If other devices do not receive another CDP packet from the device before this time elapses, the device has probably gone offline. The default value is 180. The packet hold time should always be greater than the value in the Packets Sent Every field.

Packets Sent Every (optional)

The number of seconds between each CDP packet that the device sends. The default value is 60. This value should always be less than the packet hold time.

• Ethernet--When selected, the device sends CDP packets through its Ethernet port and monitors the Ethernet for CDP packets from other devices.

• Access point Radio Options--When selected, the device sends CDP packets through its internal radio port and monitors the internal radio for CDP packets from other devices.

Note: A MIB file is available for use with CDP. The filename is CISCO-CDP-MIB.my, and you can download the MIB at the following URL: http://www.cisco.com/public/mibs/v1/CISCO-CDP-MIB-V1SMI.my

CDP Neighbors Table

This section displays the type of device that is discovered. Specifically, it displays the following values:

Device ID

The configured ID, MAC address, or serial number of the device.

Interface

The number and type of the local interface protocol being used.

Hold time

The number of remaining seconds the current device holds the CDP advertisement from a transmitting router before discarding it.

Capability

The device type as listed in the CDP Neighbors table. Possible values are R for router, T for transparent bridge, B for source-routing bridge, S for switch, H for host, I for IGMP device, or r for repeater. If you click the calculator image, you see a popup with the legend of code to capability.

Platform

The device product number.

Port ID

The protocol and port number of the device.