The Cisco Discovery Protocol (CDP) is a proprietary layer 2 network protocol developed by Cisco Systems that runs on most Cisco equipment and is used to share information about other directly connected Cisco equipment such as the platform, device identifiers, the operating system version and IP address.
By default, cdp is enabled on all Cisco routers at both global level and per interface level.
To see if cdp are enabled, use command "show cdp".
To inspect the information about the switches and routers directly connected to your cisco device, use command "show cdp neighbor".
To get even more information, use command "show cdp neighbor detail" or "show cdp entry *".
To check the cdp information at all the interfaces, use command "show cdp interface".
To display cdp packet checksum errors, use command "show cdp traffic".
To turn on cdp at global levle, use command "cdp run".
To turn on cdp at per inteface level, use command "cdp enable".
To turn off cdp at global level, use command "no cdp run".
To turn off cdp at per interface level, use command "no cdp enable".