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Displaying the ARP and Neighbor Discovery cache for VMkernel network interfaces (2000130)

Purpose

This article provides methods for listing the Address Resolution Protocol (ARP) and Neighbor Discovery (ND) cache maintained for VMkernel network interfaces on ESX/ESXi. Use of this information is outside the scope of this article, but may be useful when troubleshooting

ARP and ND Protocol are used in IPv4 and IPv6 respectively at the network layer for discovering other devices on the same link. A cache of neighboring devices' IP and MAC addresses is maintained by the ESX/ESXi host's VMkernel networking stack. The cache is used for mapping logical IP addresses to link-layer MAC addresses for outbound traffic on VMkernel network interfaces.

Note: This information is only for ESX/ESXi 4.1 and higher. For previous versions of ESX/ESXi, consider capturing network traffic on the VMkernel interface and reviewing it to see whether ARP traffic is being issued and responded to. For more information, see Capturing a network trace in ESXi 4.x using Tech Support Mode (1031186).

Resolution

To review the ARP and ND cache for the VMkernel network interfaces on an ESX or ESXi host, use the local or remote esxcli command. This command is available at the local console of the ESX/ESXi host, and usable remotely from the vSphere Command Line Interface (vCLI) or from the vSphere Management Assistant (vMA) appliance. For installation and/or usage instruction, see the relevant documentation.

  1. Open a console session to the location where the esxcli command is available.


  2. Display the list of known network neighbors in the ARP and ND cache for all VMkernel network interfaces using one of the commands:

    • On ESXi 4.1:

      esxcli [--server hostname --username root --password rootpassword] network neighbor list

    • On ESXi 5.x:

      esxcli [--server hostname --username root --password rootpassword] network ip neighbor list

    Note: If running locally on the ESX/ESXi host console, no server hostname or authentication is required for the esxcli command.

    The output appears similar to:

    Neighbor     Mac Address       vmknic Expiry(sec)
    --------     -----------       ------ -----------
    10.5.6.7     00:50:56:9a:00:7a vmk0   1200
    10.5.6.8     00:50:56:9a:00:57 vmk0   1197
    10.5.6.9     00:50:56:9a:00:3e vmk0   277
    10.200.1.10  00:50:56:9a:01:09 vmk1   979

Additional Information

The VMware ESX Service Console maintains a separate MAC address cache. For more information, see Troubleshooting network connection issues using Address Resolution Protocol (ARP) (1008184).

See Also

Request a Product Feature

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