Configuring LLDP and LLDP-MED

Restrictions for LLDP

  • 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 vlan vlan-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.

  • When Cisco Discovery Protocol and LLDP are both in use within the same switch, it is necessary to disable LLDP on interfaces where Cisco Discovery Protocol is in use for power negotiation. LLDP can be disabled at interface level with the commands no lldp tlv-select power-management or no lldp transmit / no lldp receive .

Information About LLDP and LLDP-MED

This section describes about LLDP and LLDP-MED.

LLDP

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, switches, and controllers). 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 device 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 Supported TLVs

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-MED

LLDP for Media Endpoint Devices (LLDP-MED) is an extension to LLDP that operates between endpoint devices such as IP phones and network devices. 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 Supported TLVs

LLDP-MED supports these TLVs:

  • 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 device, 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 devices 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 device 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 device 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 [max max-wattage] | never | static [max max-wattage] } interface configuration command. By default the PoE interface is in auto mode;

  • Inventory management TLV

    Allows an endpoint to send detailed inventory information about itself to the device, 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 device 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.

Default LLDP Configuration

Table 1. Default LLDP Configuration

Feature

Default Setting

LLDP global state

Enabled

LLDP holdtime (before discarding)

120 seconds

LLDP timer (packet update frequency)

30 seconds

LLDP reinitialization delay

2 seconds

LLDP tlv-select

Enabled

LLDP interface state

Enabled

LLDP receive

 Enabled

LLDP transmit

Enabled

LLDP med-tlv-select

Enabled. When LLDP is globally enabled, LLDP-MED-TLV is also enabled.

How to Configure LLDP and LLDP-MED

This section provides the procedures to configure LLDP and LLDP-MED.

Enabling LLDP

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

lldp run

Example:

Device(config)# lldp run

Enables LLDP globally on the device.

Step 4

interface interface-id

Example:

Device(config)# interface gigabitethernet1/1

Specifies the interface on which you are enabling LLDP, and enters interface configuration mode.

Step 5

lldp transmit

Example:

Device(config-if)# lldp transmit

Enables the interface to send LLDP packets.

Step 6

lldp receive

Example:

Device(config-if)# lldp receive

Enables the interface to receive LLDP packets.

Step 7

end

Example:

Device(config-if)# end

Exits interface configuration mode, and returns to privileged EXEC mode.

Step 8

show lldp

Example:

Device# show lldp

Verifies the configuration.

Step 9

copy running-config startup-config

Example:

Device# 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.


Note

Steps 3 through 6 are optional and can be performed in any order.

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

lldp holdtime seconds

Example:

Device(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 4

lldp reinit delay

Example:

Device(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 5

lldp timer rate

Example:

Device(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 6

lldp tlv-select

Example:

Device(config)# tlv-select

(Optional) Specifies the LLDP TLVs to send or receive.

Step 7

interface interface-id

Example:

Device(config)# interface gigabitethernet1/1

Specifies the interface on which you are enabling LLDP, and enters interface configuration mode.

Step 8

lldp med-tlv-select

Example:

 Device(config-if)# lldp med-tlv-select inventory management

(Optional) Specifies the LLDP-MED TLVs to send or receive.

Step 9

end

Example:

Device(config-if)# end

Exits interface configuration mode, and returns to privileged EXEC mode.

Step 10

show lldp

Example:

Device# show lldp

Verifies the configuration.

Step 11

copy running-config startup-config

Example:

Device# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring LLDP-MED TLVs

By default, the device 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

Follow these steps to enable a TLV on an interface:

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

interface interface-id

Example:

Device(config)# interface gigabitethernet1/1

Specifies the interface on which you are enabling LLDP, and enters interface configuration mode.

Step 4

lldp med-tlv-select

Example:

Device(config-if)# lldp med-tlv-select inventory management

Specifies the TLV to enable.

Step 5

end

Example:

Device(config-if)# end

Exits global configuration mode, and returns to privileged EXEC mode.

Step 6

copy running-config startup-config

Example:

Device# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring Network-Policy TLV

Procedure

  Command or Action Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password, if prompted.

Step 2

configure terminal

Example:

Device# configure terminal

Enters global configuration mode.

Step 3

network-policy profile profile number

Example:

Device(config)# network-policy profile 1

Specifies the network-policy profile number, and enters network-policy configuration mode. The range is 1 to 4294967295.

Step 4

{voice | voice-signaling} vlan [vlan-id {cos cvalue | dscp dvalue}] | [[dot1p {cos cvalue | dscp dvalue}] | none | untagged]

Example:

Device(config-network-policy)# voice vlan 100 cos 4

Configures the policy attributes:

  • voice : Specifies the voice application type.

  • voice-signaling : Specifies the voice-signaling application type.

  • vlan : Specifies the native VLAN for voice traffic.

  • vlan-id : (Optional) Specifies the VLAN for voice traffic. The range is 1 to 4094.

  • cos cvalue : (Optional) Specifies the Layer 2 priority class of service (CoS) for the configured VLAN. The range is 0 to 7; the default is 5.

  • dscp dvalue : (Optional) Specifies the differentiated services code point (DSCP) value for the configured VLAN. The range is 0 to 63; the default is 46.

  • dot1p : (Optional) Configures the telephone to use IEEE 802.1p priority tagging and use VLAN 0 (the native VLAN).

  • none : (Optional) Do not instruct the IP telephone about the voice VLAN. The telephone uses the configuration from the telephone key pad.

  • untagged : (Optional) Configures the telephone to send untagged voice traffic. This is the default for the telephone.

Step 5

exit

Example:

Device(config)# exit

Returns to global configuration mode.

Step 6

interface interface-id

Example:

Device(config)# interface gigabitethernet1/1

Specifies the interface on which you are configuring a network-policy profile, and enters interface configuration mode.

Step 7

network-policy profile number

Example:

Device(config-if)# network-policy 1

Specifies the network-policy profile number.

Step 8

lldp med-tlv-select network-policy

Example:

Device(config-if)# lldp med-tlv-select network-policy

Specifies the network-policy TLV.

Step 9

end

Example:

Device(config)# end

Returns to privileged EXEC mode.

Step 10

show network-policy profile

Example:

Device# show network-policy profile

Verifies the configuration.

Step 11

copy running-config startup-config

Example:

Device# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuration Examples for LLDP and LLDP-MED

This section provides configuration examples for LLDP and LLDP-MED.

Examples: Configuring Network-Policy TLV

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: 


Device# configure terminal
Device(config)# network-policy 1
Device(config-network-policy)# voice vlan 100 cos 4
Device(config-network-policy)# exit
Device(config)# interface gigabitethernet1/1
Device(config-if)# network-policy profile 1
Device(config-if)# lldp med-tlv-select network-policy

This example shows how to configure the voice application type for the native VLAN with priority tagging:


Device-config-network-policy)# voice vlan dot1p cos 4
Device-config-network-policy)# voice vlan dot1p dscp 34

Monitoring and Maintaining LLDP and LLDP-MED

Use the following commands for monitoring and maintaining LLDP and LLDP-MED.

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 entry entry-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-tag string

Displays the location information for the specified administrative tag or site.

show location civic-location identifier id

Displays the location information for a specific global civic location.

show location elin-location identifier id

Displays the location information for an emergency location

show network-policy profile

Displays the configured network-policy profiles.