3.6 Cisco Discovery Protocol Flashcards
What is CDP?
Cisco Discovery Protocol (CDP) is a layer 2 (Data Link) protocol that runs on all Cisco devices. CDP broadcasts periodic advertisements.
When should you disable CDP?
On routers on the edge of the network and user facing interfaces
Router(config)#show cdp
Checks the status of CDP
Router(config)#no cdp run
Disables CDP for all interfaces on a device
Router(config)#cdp run
Enables CDP for all interfaces on a device
Router(config)#no cdp enable
Disables CDP on that interface, but keeps CDP enabled for the device.
Router(config)#cdp enable
Enables CDP on that interface.
Router#show cdp neighbors
Checks for the status of CDP and shows a list of neighboring devices.
What details does the command show cdp neighbors show
Device identifier – provides the host name of the neighboring device
Port identifiers – provides the name of the local and remote port
Capabilities list – indicates whether the device is a switch or a router
Platform – indicates the hardware platform of the device
Router#show cdp neighbors detail
Provides the same information as show cdp neighbors as well as additional information such as IP address and IOS version.
Router#show cdp interface
Provides the full CDP configuration for the interface.
Router#show ip interface brief
Provides the abbreviated CDP configuration for the interface.
Router(config)#lldp run
Enables LLDP globally on the router.
Router(config)#no lldp run
Disables LLDP on a router and prevents the router from exchanging LLDP packets.
Router(config-if)#lldp transmit
Enables the interface to send LLDP information.
Router(config-if)#no lldp transmit
Disables the interface from sending LLDP information.
Router(config-if)#lldp receive
Enables the interface to receive LLDP information.
Router(config-if)#no lldp receive
Disables the interface from receiving LLDP information.
Router#show lldp
Displays LLDP information, including frequency of transmissions, hold time for packets to be sent, and the delay time for LLDP initialization on an interface.
Router#show lldp interface
Displays information about interfaces that have LLDP enabled, including transmit and receive configuration, as well as the current state.
Router#show lldp neighbors
Displays information about all neighboring Cisco devices, including: Device ID Local interface Holdtime Capability Port ID
Router#show lldp neighbors detail
In addition to displaying all the same information as the show lldp neighbors command, it also displays the following:
Physical media information and capabilities
A description of the neighbor
Software version
Router#show lldp entry
Displays information about all neighbors similar to the show lldp neighbors detail command.
Router#show lldp entry neighbor_name
Displays similar information for the specified LLDP neighbor.
Router#show lldp traffic
Shows the current state of LLDP traffic, including the number of frames in and out, the number of dropped frames, and the number of Type-Length-Values (TLVs) discarded or un-recognized.
Router#clear lldp counters
Resets traffic counters to 0.
Router#show lldp errors
Shows lldp error counters.
Router(config)#lldp holdtime [10-255]
Specifies the amount of time that information in a packet is still valid. The default is 120 seconds. Use the no lldp holdtime command to reset the value to its default.
Router(config)#lldp timer [5-254]
Specifies how often LLDP packets are exchanged. The default is 30 seconds. Use the no lldp timer command to reset the value to its default.
What does the protocol LLDP do
allows a network engineer to discover non-Cisco devices in the network
