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Using LLDP to detect network connectivity

Using LLDP to detect network connectivity consists of reviewing deployment considerations, enabling it on all ports, viewing neighbor devices, and adjusting LLDP configuration values as needed.

Before you begin

LLDP must also be enabled on any switches and routers before information about neighbor devices can be displayed.

About this task

ONTAP currently reports the following type-length-value structures (TLVs):

  • Chassis ID

  • Port ID

  • Time-To-Live (TTL)

  • System name

    The system name TLV is not sent on CNA devices.

Certain converged network adapters (CNAs) contain offload support for LLDP:

  • LLDP offload is used for Data Center Bridging (DCB).

  • Displayed information might differ between the cluster and the switch.

    For example, the Chassis ID and Port ID data displayed by the switch might be different for CNA and non-CNA ports, but the data displayed by the cluster is consistent for these port types.

Note
The LLDP specification defines access to the collected information through an SNMP MIB. However, ONTAP does not currently support the LLDP MIB.
  • Enabling or disabling LLDP
    To discover and send advertisements to LLDP-compliant neighboring devices, LLDP must be enabled on each node of the cluster. By default, LLDP is disabled on all ports of a node.
  • Viewing LLDP neighbor information
    You can view information about the neighboring devices that are connected to each port of the nodes of your cluster, provided that the port is connected to an LLDP-compliant device. You use the network device-discovery show command to view neighbor information.
  • Adjusting the interval for transmitting LLDP advertisements
    LLDP advertisements are sent to LLDP neighbors at periodic intervals. You can increase or decrease the interval for sending LLDP advertisements depending on network traffic and changes in the network topology.
  • Adjusting the Time-To-Live value for LLDP advertisements
    Time-To-Live (TTL) is the period of time for which LLDP advertisements are stored in cache in neighboring LLDP-compliant devices. TTL is advertised in each LLDP packet and is updated whenever an LLDP packet is received by a node. TTL can be modified in outgoing LLDP frames.