Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.
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The Cisco Discovery Protocol (CDP) is a device discovery protocol that runs over Layer 2 (the data link layer) on all Cisco-manufactured devices (routers, bridges, access servers, and switches). CDP allows network management applications to automatically discover and learn about other Cisco devices connected to the network.
To support non-Cisco devices and to allow for interoperability between other devices, the switch supports the IEEE 802.1AB Link Layer Discovery Protocol (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. This protocol can advertise details such as configuration information, device capabilities, and device identity.
The switch supports these basic management TLVs. These are mandatory LLDP TLVs.
Port description TLV
System name TLV
System description TLV
System capabilities TLV
Management address TLV
These organizationally specific LLDP TLVs are also advertised to support LLDP-MED.
Port VLAN ID TLV (IEEE 802.1 organizationally specific TLVs)
MAC/PHY configuration/status TLV (IEEE 802.3 organizationally specific TLVs)
LLDP and Cisco Switch Stacks
A switch stack appears as a single switch in the network. Therefore, LLDP discovers the switch stack, not the individual stack members.
LLDP for Media Endpoint Devices (LLDP-MED) is an extension to LLDP that operates between endpoint devices such as IP phones and network devices such as switches. It specifically provides support for voice over IP (VoIP) applications and provides additional TLVs for capabilities discovery, network policy, Power over Ethernet, inventory management and location information. By default, all LLDP-MED TLVs are enabled.
LLDP-MED capabilities TLV
Allows LLDP-MED endpoints to determine the capabilities that the connected device supports and has enabled.
Network policy TLV
Allows both network connectivity devices and endpoints to advertise VLAN configurations and associated Layer 2 and Layer 3 attributes for the specific application on that port. For example, the switch can notify a phone of the VLAN number that it should use. The phone can connect to any switch, obtain its VLAN number, and then start communicating with the call control.
By defining a network-policy profile TLV, you can create a profile for voice and voice-signaling by specifying the values for VLAN, class of service (CoS), differentiated services code point (DSCP), and tagging mode. These profile attributes are then maintained centrally on the switch and propagated to the phone.
Power management TLV
Enables advanced power management between LLDP-MED endpoint and network connectivity devices. Allows switches and phones to convey power information, such as how the device is powered, power priority, and how much power the device needs.
LLDP-MED also supports an extended power TLV to advertise fine-grained power requirements, end-point power priority, and end-point and network connectivity-device power status. LLDP is enabled and power is applied to a port, the power TLV determines the actual power requirement of the endpoint device so that the system power budget can be adjusted accordingly. The switch processes the requests and either grants or denies power based on the current power budget. If the request is granted, the switch updates the power budget. If the request is denied, the switch turns off power to the port, generates a syslog message, and updates the power budget. If LLDP-MED is disabled or if the endpoint does not support the LLDP-MED power TLV, the initial allocation value is used throughout the duration of the connection.
You can change power settings by entering the power inline {auto [maxmax-wattage] | never | static [maxmax-wattage]} interface configuration command. By default the PoE interface is in auto mode; If no value is specified, the maximum is allowed (30 W).
Inventory management TLV
Allows an endpoint to send detailed inventory information about itself to the switch, including information hardware revision, firmware version, software version, serial number, manufacturer name, model name, and asset ID TLV.
Location TLV
Provides location information from the switch to the endpoint device. The location TLV can send this information:
Civic location information
Provides the civic address information and postal information. Examples of civic location information are street address, road name, and postal community name information.
ELIN location information
Provides the location information of a caller. The location is determined by the Emergency location identifier number (ELIN), which is a phone number that routes an emergency call to the local public safety answering point (PSAP) and which the PSAP can use to call back the emergency caller.
Geographic location information
Provides the geographical details of a switch location such as latitude, longitude, and altitude of a switch.
custom location
Provides customized name and value of a switch location.
Wired Location Service
The switch uses the location service feature to send location and attachment tracking information for its connected devices to a Cisco Mobility Services Engine (MSE). The tracked device can be a wireless endpoint, a wired endpoint, or a wired switch or controller. The switch notifies the MSE of device link up and link down events through the Network Mobility Services Protocol (NMSP) location and attachment notifications.
The MSE starts the NMSP connection to the switch, which opens a server port. When the MSE connects to the switch there are a set of message exchanges to establish version compatibility and service exchange information followed by location information synchronization. After connection, the switch periodically sends location and attachment notifications to the MSE. Any link up or link down events detected during an interval are aggregated and sent at the end of the interval.
When the switch determines the presence or absence of a device on a link-up or link-down event, it obtains the client-specific information such as the MAC address, IP address, and username. If the client is LLDP-MED- or CDP-capable, the switch obtains the serial number and UDI through the LLDP-MED location TLV or CDP.
Depending on the device capabilities, the switch obtains this client information at link up:
Slot and port specified in port connection
MAC address specified in the client MAC address
IP address specified in port connection
802.1X username if applicable
Device category is specified as a wired station
State is specified as new
Serial number, UDI
Model number
Time in seconds since the switch detected the association
Depending on the device capabilities, the switch obtains this client information at link down:
Slot and port that was disconnected
MAC address
IP address
802.1X username if applicable
Device category is specified as a wired station
State is specified as delete
Serial number, UDI
Time in seconds since the switch detected the disassociation
When the switch shuts down, it sends an attachment notification with the state delete and the IP address before closing the NMSP connection to the MSE. The MSE interprets this notification as disassociation for all the wired clients associated with the switch.
If you change a location address on the switch, the switch sends an NMSP location notification message that identifies the affected ports and the changed address information.
Default LLDP Configuration
Table 1 Default LLDP Configuration
Feature
Default Setting
LLDP global state
Disabled
LLDP holdtime (before discarding)
120 seconds
LLDP timer (packet update frequency)
30 seconds
LLDP reinitialization delay
2 seconds
LLDP tlv-select
Disabled to send and receive all TLVs
LLDP interface state
Disabled
LLDP receive
Disabled
LLDP transmit
Disabled
LLDP med-tlv-select
Disabled to send all LLDP-MED TLVs. When LLDP is globally enabled, LLDP-MED-TLV is also enabled.
Configuration Guidelines
If the interface is configured as a tunnel port, LLDP is automatically disabled.
If you first configure a network-policy profile on an interface, you cannot apply the switchport voice vlan command on the interface. If the switchport voice vlanvlan-id is already configured on an interface, you can apply a network-policy profile on the interface. This way the interface has the voice or voice-signaling VLAN network-policy profile applied on the interface.
You cannot configure static secure MAC addresses on an interface that has a network-policy profile.
For wired location to function, you must first enter the ip device tracking global configuration command.
How to Configure LLDP, LLDP-MED, and Wired Location Service
Beginning in privileged EXEC mode, follow these steps to enable LLDP:
SUMMARY STEPS
1.configure terminal
2.lldp run
3.interfaceinterface-id
4.lldp transmit
5.lldp receive
6.end
7.show lldp
8.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
configure terminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 2
lldp run
Example:
Switch (config)# lldp run
Enables LLDP globally on the switch.
Step 3
interfaceinterface-id
Example:
Switch (config)# interface
gigabitethernet2/0/1
Specifies the interface on which you are enabling LLDP, and enter interface configuration mode.
Step 4
lldp transmit
Example:
Switch(config-if)# lldp transmit
Enables the interface to send LLDP packets.
Step 5
lldp receive
Example:
Switch(config-if)# lldp receive
Enables the interface to receive LLDP packets.
Step 6
end
Example:
Switch(config-if)# end
Returns to privileged EXEC mode.
Step 7
show lldp
Example:
Switch# show lldp
Verifies the configuration.
Step 8
copy running-config startup-config
Example:
Switch# copy running-config
startup-config
(Optional) Saves your entries in the configuration file.
Configuring LLDP Characteristics
You can configure the frequency of LLDP updates, the amount of time to hold the information before discarding it, and the initialization delay time. You can also select the LLDP and LLDP-MED TLVs to send and receive.
Beginning in privileged EXEC mode, follow these steps to configure the LLDP characteristics.
Note
Steps 2 through 5 are optional and can be performed in any order.
SUMMARY STEPS
1.configureterminal
2.lldp holdtimeseconds
3.lldp reinitdelay
4.lldp timerrate
5.lldp tlv-select
6.interfaceinterface-id
7.lldp med-tlv-select
8.end
9.show lldp
10.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 2
lldp holdtimeseconds
Example:
Switch(config)# lldp holdtime 120
(Optional) Specifies the amount of time a receiving device should hold the information from your device before discarding it.
The range is 0 to 65535 seconds; the default is 120 seconds.
Step 3
lldp reinitdelay
Example:
Switch(config)# lldp reinit 2
(Optional) Specifies the delay time in seconds for LLDP to initialize on an interface.
The range is 2 to 5 seconds; the default is 2 seconds.
Step 4
lldp timerrate
Example:
Switch(config)# lldp timer 30
(Optional) Sets the sending frequency of LLDP updates in seconds.
The range is 5 to 65534 seconds; the default is 30 seconds.
Step 5
lldp tlv-select
Example:
Switch(config)# tlv-select
(Optional) Specifies the LLDP TLVs to send or receive.
Step 6
interfaceinterface-id
Example:
Switch (config)# interface
gigabitethernet2/0/1
Specifies the interface on which you are enabling LLDP, and enter interface configuration mode.
(Optional) Specifies the LLDP-MED TLVs to send or receive.
Step 8
end
Example:
Switch (config-if)# end
Returns to privileged EXEC mode.
Step 9
show lldp
Example:
Switch# show lldp
Verifies the configuration.
Step 10
copy running-config startup-config
Example:
Switch# copy running-config
startup-config
(Optional) Saves your entries in the configuration file.
Configuring LLDP-MED TLVs
By default, the switch only sends LLDP packets until it receives LLDP-MED packets from the end device. It then sends LLDP packets with MED TLVs, as well. When the LLDP-MED entry has been aged out, it again only sends LLDP packets.
By using the lldp interface configuration command, you can configure the interface not to send the TLVs listed in the following table.
Table 2 LLDP-MED TLVs
LLDP-MED TLV
Description
inventory-management
LLDP-MED inventory management TLV
location
LLDP-MED location TLV
network-policy
LLDP-MED network policy TLV
power-management
LLDP-MED power management TLV
Beginning in privileged EXEC mode, follow these steps to enable a TLV on an interface:
SUMMARY STEPS
1.configureterminal
2.interfaceinterface-id
3.lldp med-tlv-select
4.end
5.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
configureterminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 2
interfaceinterface-id
Example:
Switch(config)# interface
gigabitethernet2/0/1
Specifies the interface on which you are configuring an LLDP-MED TLV, and enter interface configuration mode.
(Optional) Saves your entries in the configuration file.
Configuring Network-Policy TLV
Beginning in privileged EXEC mode, follow these steps to create a network-policy profile, configure the policy attributes, and apply it to an interface.
This example shows how to configure VLAN 100 for voice application with CoS and to enable the network-policy profile and network-policy TLV on an interface:
Monitoring and Maintaining LLDP, LLDP-MED, and Wired Location Service
Commands for monitoring and maintaining LLDP, LLDP-MED, and wired location service.
Command
Description
clear lldp counters
Resets the traffic counters to zero.
clear lldp table
Deletes the LLDP neighbor information table.
clear nmsp statistics
Clears the NMSP statistic counters.
show lldp
Displays global information, such as frequency of transmissions, the holdtime for packets being sent, and the delay time before LLDP initializes on an interface.
show lldp entryentry-name
Displays information about a specific neighbor.
You can enter an asterisk (*) to display all neighbors, or you can enter the neighbor name.
show lldp interface [interface-id]
Displays information about interfaces with LLDP enabled.
You can limit the display to a specific interface.
show lldp neighbors [interface-id] [detail]
Displays information about neighbors, including device type, interface type and number, holdtime settings, capabilities, and port ID.
You can limit the display to neighbors of a specific interface or expand the display for more detailed information.
show lldp traffic
Displays LLDP counters, including the number of packets sent and received, number of packets discarded, and number of unrecognized TLVs.
show location admin-tagstring
Displays the location information for the specified administrative tag or site.
show location civic-location identifierid
Displays the location information for a specific global civic location.
show location elin-location identifierid
Displays the location information for an emergency location
show network-policy profile
Displays the configured network-policy profiles.
show nmsp
Displays the NMSP information
Additional References for LLDP, LLDP-MED, and Wired Location Service
MIBs
MIB
MIBs Link
All supported MIBs for this release.
To locate and download MIBs for selected platforms, Cisco IOS
releases, and feature sets, use Cisco MIB Locator found at the
following URL:
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