VMware ESXi Configuration Changes

Network Interface Failover/Failback

When a switch port goes down during maintenance or a hardware failure, VMware ESXi can automatically fail over network traffic to another network adapter to ensure that traffic continues to flow. If failback is enabled, the traffic will be moved back to the original network adapter when the port comes back up.

In some cases, the physical port can come back up before the network fabric overlay has been re-established. This can result in dropped packets for 30-60 seconds.

To avoid this, ESXi can be configured to wait a specific amount of time before failing back to the original network adapter. This setting must be adjusted at each ESXi host in Advanced System Settings.

The setting 'Net.TeamPolicyUpDelay' can be adjusted from the default value of 100 ms to a higher value. Two minutes, or 120000 ms, should be adequate time for the network overlay to re-establish.

For more information, see VMware KB Article 2014075.