Product Documentation

Configuring Link Layer Discovery Protocol

Jun 11, 2014

The NetScaler ADC supports the industry standard (EEE 802.1AB) Link Layer Discovery Protocol (LLDP). LLDP is a layer 2 protocol that enables the NetScaler ADC to advertise its identity and capabilities to the directly connected devices, and also learn the identity and capabilities of these neighbour devices. Using LLDP, the NetScaler ADC transmits and receives information in the form of LLDP messages known as LLDP packet data units (LLDPUs).

An LLDPU is a sequence of type, length, value (TLV) information elements. Each TLV holds a specific type of information about the device that transmits the LLDPDU. The NetScaler ADC sends the following TLVs in each LLDPU:
  • Chassis ID
  • Port ID
  • Time-to-live value
  • System name
  • System description
  • Port description
  • System capabilities
  • Management address
  • Port VLAN ID
  • Link aggregation
Note: You cannot specify the TLVs to be sent in LLDP messages.
NetScaler interfaces support the following LLDP modes:
  • NONE. The interface neither receives from nor transmits LLDP messages to the directly connected device.
  • TRANSMITTER. The interface transmits LLDP messages to the directly connected device but does not receive LLPD messages from the directly connected device.
  • RECEIVER. The interface receives LLDP messages from the directly connected device but does transmit LLPD messages to the directly connected device.
  • TRANSCEIVER. The interface transmits LLDP messages to and receives LLDP messages from the directly connected device.

The LLDP mode of an interface depends on the LLDP mode configured at the global and the interface levels. The following table shows the modes resulting from the available combinations of global- and interface-level settings:

Interface Level LLDP mode Global Level LLDP mode
NONE TRANSMITTER RECEIVER TRANSCEIVER
NONE NONE NONE NONE NONE
TRANSMITTER NONE TRANSMITTER NONE TRANSMITTER
RECEIVER NONE NONE RECEIVER RECEIVER
TRANSCEIVER NONE TRANSMITTER RECEIVER TRANSCEIVER
Transmitting LLDP messages

The NetScaler ADC transmits LLDPUs from interfaces that are operating in either TRANSMITTER or TRANSCEIVER LLDP mode.

Following are the global LLDP transmitting parameters on the NetScaler ADC:
  • Timer. Interval, in seconds, between LLDPUs that the NetScaler ADC sends to a directly connected device.
  • Holdtime Multiplier. A multiplier for calculating the duration for which the receiving device stores the LLDP information in its database before discarding or removing it. The duration is calculated as the Holdtime Multiplier parameter value multiplied by the Timer parameter value.
Receiving LLDP Messages

The NetScaler ADC stores the LLDPDU information in its Management Information base (MIB). The stored LLDP information is classified or grouped under the ID of the interface that received the LLDPDU. The NetScaler ADC retains this LLDP information for the duration specified in the received LLDPU.

If the ADC receives another LLDPDU on an interface before the stored LLDP information for that interface is discarded, the ADC replaces the stored LLDP information for that interface with information in the new LLDPDU.

Configuration Steps
Configuring LLDP on a NetScaler appliance consists of the following tasks:
  1. Set global level LLDP parameters. In this task, you set the global LLDP parameters such as LLDP Timer, Hold Time Multiplier, and LLDP mode.
  2. Set the interface level LLDP parameters. In this task, you set the LLDP mode for an interface.
  3. (Optional) Display neighbor-device information. You can display the neighbor-device LLDP information collected on all of the NetScaler ADC’s interfaces, or just the LLDP information collected on specified interfaces. If you do not specify an interface, the information is shown for all interfaces.
Following are the prerequisites for configuring LLDP on a NetScaler ADC:
  1. Make sure that you understand the standard LLDP protocol (IEEE 802.1AB).
  2. Verify that you have configured LLDP on the desired directly connected devices.
To set global level LLDP parameters by using the command line interface
At the command prompt, type:
  • set lldp param [-[-holdtimeTxMult <positive_integer>][-timer <positive_integer>] [-Mode <Mode>]
  • show lldp param
To set the global level LLDP parameters by using configuration utility
  1. Navigate to System > Network, and click Configure LLDP Parameters.
  2. Set the following parameters:
    • Hold Timer Multiplier
    • Timer
    • Mode
To configure an interface for LLDP by using the command line interface
At the command prompt, type:
  • set interface <id> -lldpmode <lldpmode>
  • show interface <id>
To configure an interface for LLDP by using configuration utility

Navigate to System > Network > Interfaces, open the interface, and set the LLDP mode parameter.

To display neighbor device information by using the command line interface
At the command prompt, type one of the following commands:
  • show lldp neighbors
  • show lldp neighbors <ifnum>
To display neighbor device information by using configuration utility

Navigate to System > Network > Interfaces and, in the Action list, select View LLDP Neighbors.