ESXi vMotion Network Connectivity Issues After Disabling IPv6

Products

• VMware vSphere ESXi

Issue/Introduction

• ESXi hosts within a cluster experience intermittent or complete loss of vMotion network connectivity.
• One host may still be able to ping vMotion IP addresses on hosts in a different cluster, but fails to ping other vMotion IP addresses in its local cluster.
• Other hosts in the cluster may be unable to ping any vMotion IP addresses locally or remotely.

 

Environment

VMware ESXi 

Cause

The underlying cause is an IPv6 Stack Dependency for ESXi. Modern ESXi kernel and networking services, including the vMotion process, are designed to operate in a dual-stack environment (supporting both IPv4 and IPv6). When the IPv6 stack is disabled (e.g., via esxcli or the vSphere Client), internal services responsible for managing vMotion fail to initialize gracefully when they attempt to bind to both the IPv4 and IPv6 components. This failure prevents the vMotion network service from starting or operating correctly, resulting in connectivity issues

Resolution

Re-enable IPv6 on the affected ESXi hosts to restore the network stack to its default, stable, dual-stack state. This allows the vMotion service to correctly initialize and use the IPv4 path for migration, resolving the intermittent connectivity issues.

Steps to do this: 

Option 1: Using the vSphere Client

1. Log in to the vSphere Client and navigate to the ESXi host.
   
   
2. Go to the Configure tab.
   
   
3. Under System, select Advanced Settings.
   
   
4. Search for the setting Net.UseIPv6.
   
   
5. Set the value of Net.UseIPv6 to 1 (Enabled).
   
   
6. Click OK to apply the change.
   
   
7. Reboot the ESXi host for the change to take full effect on the kernel networking stack.

Option 2: Using the ESXi Command Line Interface (CLI)

1. Log in to the ESXi host's shell (e.g., via SSH).
   
   
2. Use the esxcli command to set the configuration option:
   esxcli system settings advanced set -o /Net/UseIPv6 -i 1
   
   
3. Verify the setting is active:
   esxcli system settings advanced list -o /Net/UseIPv6
   
   
4. Reboot the ESXi host for the change to take full effect:
   reboot
   
   
5. After the host reboots, test vMotion connectivity across the cluster. If the issue was related to the IPv6 stack dependency, connectivity should be restored.

Additional Information

If you are contacting Broadcom support about this issue, please provide the following:

• ESXi host support bundles for the hosts in the affected cluster.
• A clear description of the specific connectivity tests (ping results) conducted.

For information on collecting and uploading logs:

Uploading files to cases on the Broadcom Support Portal.

Creating and managing Broadcom support cases.