Getting CDP Timers and Holdtime Information

The show cdp command gives you information about two CDP global parameters that can be configured on Cisco devices:

• CDP Timer is how often CDP packets are transmitted out all active interfaces.
• CDP holdtime is the amount of time that the device will hold packets received from neighbor devices.

Both Cisco routers and Cisco switches use the same parameters.

Corp#show cdp
Global CDP information:
    Sending CDP packets every 60 seconds
    Sending a holdtime value of 180 seconds
    Sending CDPv2 advertisements is enabled

Use the global commands cdp holdtime and cdp timers to configre the CDP holdtime and timers on the router:

Corp(config)#cdp ?
    advertise-v2        CDP sends version-2 advertisements
    holdtime              Specify the holdtime (in sec) to be sent in packets
    log                       Log messages generated by CDP
    run                      Enable CDP
    source-interface  Insert the interface's IP in all CDP packets
    timer                  Specify rate (in sec) at which CDP packets are sent run

You can turn off CDP completely with the no cdp run command from the global configuration mode of a router. To turn CDP off or on for an interface, use the no cdp enable and cdp enable commands. 

Source: Cisco Certified Network Associate Study Guide, 6th Edition