vMotion Fails Between Legacy UCS and New vCenter Due to Missing vMotion Network Routing

Products

• VMware vSphere ESXi

Issue/Introduction

• vMotion fails when migrating virtual machines from a legacy environment to a new vCenter cluster.
• Cross–vCenter vMotion attempts mail fail at approximately 45%.  
• vmkping between ESXi hosts where the VM is trying to migrate between on the vMotion VMkernel interface fails with 100% packet loss.
• vmkping between ESXi hosts in the two different vCenter environments on the Management VMkernel interface succeed.
• vCenter reports the following error:

“The vMotion failed because the destination host did not receive data from the source host on the vMotion network. Please check your vMotion network settings and physical network configuration and ensure they are correct.”

 

Environment

VMware vCenter Server 
VMware vSphere ESXi

Cause

• There is no Layer 3 routing between the source and destination ESXi hosts on the dedicated vMotion network.
• While management network connectivity exists, the vMotion vmkernel interfaces are unable to communicate due to missing routing or network configuration mismatch.

Resolution

If the legacy environment is being decommissioned and dedicated vMotion routing cannot be implemented, use one of the following approaches:

Option 1: Implement Proper Routing (Recommended)

• Configure Layer 3 routing between the source and destination vMotion networks.

Option 2: Temporary Workaround Using Management Network.  Note: This workaround is supported but not considered best practice.

• As the Management network already has routing configured between the two environments, you can allow vMotion traffic to temporarily traverse the management network in order to reach the new vCenter cluster.

On each ESXi host, edit the Management VMkernel interface (vmk0):
                   1. Temporarily enable the vMotion service on vmk0.
                   2. Retry the vMotion operation.
                   3. After migration is complete, remove the vMotion service from vmk0.

Additional Information

Mixing management and vMotion traffic can:

• Impact management plane performance.
• Increase the risk of congestion during large migrations.
• A dedicated, routable vMotion network remains the recommended configuration for production environments.