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Link layer discovery protocol (LLDP)

Link Layer Discovery Protocol is the IEEE 802.1AB standard for switches to advertise their identity, significant capabilities, and neighbors on the LAN. LLDP helps you to quickly see discovered information, identify system topology, and detect faulty configurations. The information transmitted in LLDP advertisements flows in one direction only, from one device to its neighbors. This information lets the device quickly identify other devices, resulting in a LAN that interoperates smoothly and efficiently.

LLDP transmits information as packets called LLDP Data Units (LLDPDUs). An LLDPDU is transmitted within a single 802.3 Ethernet frame. A basic LLDPDU consists of a set of Type Length Value elements (TLV), each containing information about the device. A single LLDPDU contains multiple TLVs. TLVs are short information elements that communicate complex data. Each TLV advertises a single type of information.

Global settings

You can configure the following settings on the Global settings tab:

  • Status: Turn LLDP on or off.
  • Transmission interval: The interval at which LLDP advertisement updates are sent. The default value is 30. The range is from 5 to 32768.

  • Holdtime multiplier: The number of times to multiply the Transmission interval to determine how long the switch holds LLDP packets before discarding them. The default is 4 and the range is from 2 to 10.

    Example

    If the Transmission interval is 30 seconds and the Holdtime multiplier is 4, then the LLDP packets are discarded after 120 seconds.

  • Reinitialization Delay: The time in seconds before reinitializing LLDP. The default is 2. The range is from 1 to 10.

  • Transmit Delay: The time in seconds between successive LLDP frame transmissions. The default is 2 and the range is from 1 to 8191.

Click Apply to update the settings.

Local device

You can see the following LLDP information for the switch on the Local device tab:

  • Chassis ID subtype: The type of information shown in the Chassis ID column.
  • Chassis ID: Shows the switch's chassis ID.
  • System name: Shows the name of the switch.
  • System description: A description of the switch.
  • Supported capabilities: Describes the functions the switch is capable of.
  • Capabilities turned on: Describes the functions the switch has turned on.
  • Port ID subtype: Shows the port ID type.

Remote device

You can see detailed LLDP information for remote devices on the Remote device tab. By default, the tab shows the following information:

  • Port: Shows the port to which the device is connected.
  • Chassis ID subtype: The type of information shown in the Chassis ID column.
  • Chassis ID: Shows the device's chassis ID.
  • Port ID subtype: The type of information shown in the Remote ID column.
  • Remote ID: Shows the device's remote ID.
  • System name: Shows the assigned device name.

You can choose additional information about remote devices to show on the Remote device tab. Click the ellipsis Ellipsis. and select the information you want to show from the following options:

  • System description: A description of the device.
  • Supported capabilities: Shows what capabilities the device supports.
  • Capabilities turned on: Shows what capabilities the device has turned on.
  • Time to live: Shows the time to live.
  • Auto-negotiation supported: Shows if the device supports auto-negotiation.
  • Auto-negotiation turned on: Shows if the device has auto-negotiation turned on.
  • Auto-negotiation advertised capabilities: Shows the auto-negotiation capabilities of the device.
  • Operational MAU type: Shows the Medium Attachment Unit (MAU) type.
  • 802.3 maximum frame size: Shows the 802.3 maximum frame size.
  • 802.3 link aggregation capabilities: Shows if the device is capable of 802.3 link aggregation.
  • 802.3 link aggregation status: Shows if the device has 802.3 link aggregation turned on.
  • 802.3 link aggregation port ID: Shows the port ID of 802.3 link aggregation.

Click Details on the device to see the full details of any connected device.