What is Cisco Discovery Protocol (CDP
The Cisco Discovery Protocol is a Cisco Proprietary Protocol. It is a Data Link Layer Protocol and commonly called as just CDP.
The Cisco Discovery Protocol is used to collect and share information such as OS version, IP address hostname etc about directly connected Cisco devices.
CDP is enabled by default on all IOS based routers and switches.
The CDP announcements or messages are multicast to the destination address 01-00-0c-cc-cc-cc, sent out of each connected network interface.
These CDP messages or announcements are sent our every 60 seconds by default.
This protocol is designed so administrators get help and can easily collect information about local and remote connected devices.
A network administrator can use this to verify the network diagrams and accordingly correct the diagrams if any changes are done on the network.
Different media types support CDP, for example: Token Ring, Ethernet, FDDI, HDLC, ATM, Frame Relay, etc.
The CDP protocol is very useful in troubleshooting networks and documenting the devices details.
The information that the CDP message contains is as below:
- Device Name ( Which is configured using hostname command)
- Hardware Platform
- Software version (IOS version)
- Device IP address
- Hardware capability whether its Routing or Switching
- Interface that generated the CDP message
- What is null interface in a Cisco Router
- Important Cisco Discovery Protocol (CDP) IOS commands
- Network Topologies