When all NICs configured to be active on a vSwitch, the Failback setting is not applied

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

When all vmnics are configured to be active and Failback is enabled on the vSwitch, you see that the virtual machine does not return to the original vmnic after a recovery from a connection failover to another vmnic.

Environment

VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.5
VMware vSphere ESXi 6.0
VMware vSphere ESXi 5.1

Resolution

The return of a vmnic to service does not necessarily return the traffic from virtual machines to the vmnic that were using it before it went down.

This is an expected behavior, the vmnic changes that occur after a device loss and recovery is as follows:

1. Virtual machines power on with the configuration:
   
   Virtual_machine_1: Configured to vmnic2 on vSwitch1
   Virtual_machine_2: Configure to vmnic3 on vSwitch1
   
   
2. If vmnic3 goes into a down state, you see these changes:
   
   Virtual_machine_1: Configured to vmnic2 on vSwitch1
   Virtual_machine_2: Configure to vmnic2 on vSwitch1
   
   
3. When vmnic3 returns to an up (active) state, the virtual machine does not return to the original vmnic:
   
   Virtual_machine_1: Configured to vmnic2 on vSwitch1
   Virtual_machine_2: Configure to vmnic2 on vSwitch1

Note: When running an Active/Active configuration the failback setting does not apply. In an outage scenario, when a NIC becomes available again, the vmnic may fail back to the original vmnic, depending on the multipathing policy selected. For more info on multipathing, see Multipathing policies in ESXi 5.x and ESXi/ESX 4.x (1011340).

Additional Information

Multipathing policies in ESXi 5.x and ESXi/ESX 4.x
vSwitch においてすべての NIC を [有効なアダプタ] に設定している場合、フェイルバック設定が適用されない