Using Cisco Discovery Protocol
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Using Cisco Discovery Protocol
C
isco Discovery Protocol (CDP) is a proprietary protocol designed by
Cisco to help administrators collect information about both locally attached
and remote devices. By using CDP, you can gather hardware and protocol
information about neighbor devices. This information is useful for trouble-
shooting and documenting the network.
Getting CDP Timers and Holdtime Information
The show cdp command (sh cdp for short) shows information about two
CDP global parameters that can be configured on Cisco devices:
CDP timer is how often CDP packets are transmitted to all active
interfaces.
CDP holdtime is the amount of time that the device will hold packets
received from neighbor devices.
Both the Cisco routers and the Cisco switches use the same parameters.
The output on a router looks like this:
Router#sh cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Router#
Use the global commands cdp holdtime and cdp timer to configure the
CDP holdtime and timer on a router.
Router#config t
Enter configuration commands, one per line. End with
CNTL/Z.
Router(config)#cdp ?
holdtime Specify the holdtime (in sec) to be sent in
packets
timer Specify the rate at which CDP packets are
sent (in sec)
run
Router(config)#cdp timer 90
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