CDP-Cisco Discovery Protocol
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.
to disable CDP on the device; select Enabled
to enable CDP on the device. CDP is enabled by default.
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
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.
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.
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
displays the type of device that
is discovered. Specifically, it
displays the following values:
ID, MAC address, or serial number
of the device.
number and type of the local
interface protocol being used.
number of remaining seconds
the current device holds the
CDP advertisement from a transmitting
router before discarding it.
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.
protocol and port number of