Cisco Discovery Protocol (proprietary) runs only on Cisco devices; it allows you to gather information about other routers and switches. It is enabled by default. It can also be a very useful command to use while troubleshooting to see which devices are directly connected to the device you are connected to.
To disable CDP For the whole switch:
Router(config)#no cdp run
To disable CDP for an interface:
Router(config-if)#no cdp enable
show cdp show cdp neighbors show cdp neighbors detail show cdp entry
Open source CDP = LLDP
- To support non-Cisco devices and to allow for interoperability between other devices, the switch supports the IEEE 802.1AB LLDP.
- LLDP is a neighbor discovery protocol that is used for network devices to advertise information about themselves to other devices on the network.
- This protocol runs over the data-link layer, which allows two systems running different network layer protocols to learn about each other.
- LLDP supports a set of attributes that it uses to discover neighbor devices.
- These attributes contain type, length, and value descriptions and are referred to as TLVs.
- LLDP supported devices can use TLVs to receive and send information to their neighbors.
- Details such as configuration information, device capabilities, and device identity can be advertised using this protocol.
- LLDP is disabled by default
To Enable LLDP globally:
config t lldp run end
To Enable LLDP per interface:
config t int fa0/0 lldp transmit lldp receive end copy run start
clear lldp counters clear lldp table show lldp show lldp errors