ESXi Uplinks in "Stand-alone" State Due to LACP Negotiation Failure

Products

• VMware vSphere ESXi

Issue/Introduction

• ESXi uplinks (vmnics) assigned to a Link Aggregation Group (LAG) on a Distributed Virtual Switch (DVS) show a state of Stand-alone.
• Network throughput is limited to individual link speeds rather than the aggregated bandwidth of the LAG.
• Running localcli network vswitch dvs vmware lacp status get shows the following for the Partner Information:
  • Device ID: 00:00:00:00:00:00
  • Oper Key: 0
  • Port Number: 0

Environment

vSphere ESXi 8.x

vCenter Server 8.x

Cause

This issue occurs when the ESXi host fails to receive LACP Data Units (LACPDUs) from the physical switch. While the ESXi host is in "Active" mode and sending LACPDUs, the absence of a partner response prevents the LACP state machine from transitioning the links into an "Aggregated" state. To prevent a total network outage, ESXi places the links in "Stand-alone" mode.

Resolution

This is typically a physical network configuration or hardware issue. Follow these steps to resolve:

1. Verify Physical Switch Configuration

Ensure the physical switch ports connected to the ESXi host are configured for LACP Active mode. Static "On" configurations or "Passive" mode on both ends will prevent negotiation.

2. Check Protocol Statistics

Execute the following command on the ESXi host to verify packet counters:

localcli network vswitch dvs vmware lacp stats get

• If Tx LACPDUs is increasing but Rx LACPDUs is 0: The host is sending packets, but the physical switch is not responding. Focus troubleshooting on the physical switch and upstream configuration.

3. Review ESXi LACP Logs

Examine /var/log/lacp.log for the following error message, which confirms the host is not seeing a peer:

No peer response: enable link vmnicX as individual

4. Hardware Inspection

If the physical switch is confirmed to be sending LACPDUs but the host Rx counter remains 0:

• Inspect SFPs and fiber/copper cabling for physical layer errors.
• Clear port counters on the physical switch to identify if packets are being dropped on egress.