Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 12.2(58)SE

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, 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)

Note A switch stack appears as a single switch in the network. Therefore, LLDP discovers the switch stack, not the individual stack members.

When you configure LLDP or CDP location information on a per-port basis, remote devices can send Cisco Medianet location information to the switch. For information, go to
http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_cdp_discover.html.

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 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 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 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-signalling 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.

Starting with Cisco IOS Release 12.2(52)SE, when 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 (15.4 W) 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; If no value is specified, the maximum is allowed (15.4 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.

Wired Location Service

Note To use wired location service, the switch must be running the LAN Base image.

The switch uses the wired 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

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 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.
• You cannot configure a network-policy profile on a private-VLAN port.
• For wired location to function, you must first enter the ip device tracking global configuration command.

Enabling LLDP

Beginning in privileged EXEC mode, follow these steps to enable LLDP:

To disable LLDP, use the no lldp run global configuration command. To disable LLDP on an interface, use the no lldp transmit and the no lldp receive interface configuration commands.

This example shows how to globally enable LLDP.

This example shows how to enable LLDP on an interface.

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.

Use the no form of each of the LLDP commands to return to the default setting.

This example shows how to configure LLDP characteristics.

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 Table 1-2 .

Beginning in privileged EXEC mode, follow these steps to enable a TLV on an interface:

This example shows how to enable a TLV on an interface:

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.

Use the no form of each command to return to the default setting.

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:

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

Configuring Location TLV and Wired Location Service

Note To use wired location service, the switch must be running the LAN Base image.

Beginning in privileged EXEC mode, follow these steps to configure location information for an endpoint and to apply it to an interface.

Use the no form of each command to return to the default setting.

This example shows how to configure civic location information on the switch:

Beginning in privileged EXEC mode, follow these steps to enable wired location service on the switch.

Note Your switch must be running the cryptographic (encrypted) software image to enable the nmsp global configuration commands.

This example shows how to enable NMSP on a switch and to set the location notification time to 10 seconds: