Troubleshooting ESX Host Communication Failure During Powered-Off VM Import - VMware Cloud Foundation

Products

• VMware vSphere ESXi

Issue/Introduction

When performing cross-vCenter migrations or import operations for powered-off virtual machines, the task may fail with a vim.fault.HostConnectFault. This often occurs in environments where jumbo frames are required for migration traffic but the management network configuration does not support them end-to-end.

Environment

• VMware Cloud Foundation (VCF) 9.x
• vSphere 8.0.x / 9.x
• Environments utilizing jumbo frames (MTU 9000)

Cause

The management network interface (vmk0) is unable to reach the destination host using the required jumbo frame MTU. While powered-on migrations typically utilize the vMotion interface (vmk1) which may be configured correctly, powered-off migrations default to a network path that relies on the management network, leading to dropped frames and connection failures.

Resolution

To resolve this, create an additional VMkernel adapter dedicated to the provisioning network on the same subnet as the vMotion network, which is already configured for jumbo frames.

1. Navigate to the vSphere Client and select the source host.
2. Go to Configure > Networking > VMkernel adapters.
3. Click Add Networking and select VMkernel network adapter.
4. Create a new adapter on the same subnet as the vMotion VMkernel adapter.
5. Assign the new VMkernel adapter to the Provisioning network stack.
6. Ensure the MTU for this new adapter is set to 9000 to match the end-to-end network configuration.
7. Verify that the provisioning traffic now traverses this adapter, allowing the powered-off migration to complete successfully.