Duplicate MAC addresses appear in multiple ESXi 5.x hosts

Products

• VMware

Issue/Introduction

Symptoms:

• Multiple ESXi 5.x hosts have duplicate MAC addresses
• You see two hosts that have vmnics with the same MAC address
• Running the esxcfg-nics -l command on the ESXi hosts reports duplicate MAC addresses
  
  For example, running the esxcfg-nics -l command on Host 1 and Host 2 reports an output similar to:
  
  Host 1
  
  vmnic0 0000:03:00.00 igb Up 1000Mbps Full xx:xx:xx:xx:xx:x1 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic1 0000:03:00.01 igb Up 1000Mbps Full xx:xx:xx:xx:xx:x2 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic2 0000:03:00.02 igb Down 0Mbps Half xx:xx:xx:xx:xx:x3 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic3 0000:03:00.03 igb Down 0Mbps Half xx:xx:xx:xx:xx:x4 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic4 0000:08:00.00 igb Up 1000Mbps Full xx:xx:xx:xx:xx:x5 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic5 0000:08:00.01 igb Down 0Mbps Half xx:xx:xx:xx:xx:x6 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic6 0000:01:00.00 ixgbe Up 10000Mbps Full xx:xx:xx:xx:xx:x7 9000 Intel Corporation Ethernet Controller X540-AT2
  vmnic7 0000:01:00.01 ixgbe Down 0Mbps Half xx:xx:xx:xx:xx:x8 9000 Intel Corporation Ethernet Controller X540-AT2
  
  Host 2
  
  vmnic0 0000:03:00.00 igb Up 1000Mbps Full xx:xx:xx:xx:xx:y1 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic1 0000:03:00.01 igb Up 1000Mbps Full xx:xx:xx:xx:xx:y2 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic2 0000:03:00.02 igb Down 0Mbps Half xx:xx:xx:xx:xx:y3 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic3 0000:03:00.03 igb Down 0Mbps Half xx:xx:xx:xx:xx:y4 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic4 0000:08:00.00 igb Up 1000Mbps Full xx:xx:xx:xx:xx:y5 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic5 0000:08:00.01 igb Down 0Mbps Half xx:xx:xx:xx:xx:y6 1500 Intel Corporation I350 Gigabit Network Connection
  vmnic6 0000:01:00.00 ixgbe Up 10000Mbps Full xx:xx:xx:xx:xx:y7 9000 Intel Corporation Ethernet Controller X540-AT2
  vmnic7 0000:01:00.01 ixgbe Down 0Mbps Half xx:xx:xx:xx:xx:y8 9000 Intel Corporation Ethernet Controller X540-AT2

Resolution

This is a known issue with the igb driver version 2.1.11.1, which comes with ESXi 5.x.

This issue is resolved in igb driver version 3.2.10.

To download igb driver version 3.2.10, see the VMware Download Center. For information on installing the driver, please see Installing async drivers on ESXi 5.x (2005205).

This newer driver can be incorporated into the ESXi installation media using Image Builder so that this issue is avoided on new installations. For more information on how to incorporate a driver into the ESXi installation media, please see Installing async drivers on ESXi 5.x (2005205).

If Image Builder is not used and the driver is updated after ESXi is already installed, ensure to reset the configuration via DCUI, so that the system UUID gets updated. This is required because part of the system's UUID is comprised of the host's management NIC's MAC address, and must also be unique.

Warning: Using the Reset System Configuration option will return all host settings to their software defaults, including any parameters customized by the hardware manufacturer. The root password will be reset to a blank value, which may allow unauthorized access to your system. All virtual machines on the host will be unregistered. It is strongly recommended to migrate or re-register all VMs on other hosts and to place the host in maintenance mode before proceeding.

To reset the system configuration via the DCUI:

1. Login to the DCUI by pressing F2 at the direct console of the host.
2. Using the arrow keys, navigate to the last option in the main menu called Reset System Configuration and press enter.
3. You will receive a warning message. Press F11 to confirm that you wish to reset all settings to their default values.
4. You will then be prompted to restart the host. Press enter to reboot the host.

Additional Information

How to download and install async drivers in ESXi 5.x/6.x
Intel native igb driver reports incorrect or duplicate MAC addresses for interfaces of multiport i350 rNDC across ESX hosts