After ESXi Upgrade, Some vmnic Links Show “Down” When Configured with LACP

Products

• VMware vSphere ESXi

Issue/Introduction

After upgrading ESXi, certain VMNICs (uplinks of the Distributed Virtual Switch) that are configured with LACP show a link state of Down.

There is no driver feedback in /var/run/log/boot about the link status. Normally, you would expect a log entry similar to:

i40en: i40en_UpdateUplinkLinkStatus:6857: Link is up at 10000 Mbps Full Duplex for device vmnicX

However, in this case, the link status reports Down while the Admin status is Up (as seen in commands/nicinfo.sh.txt).

Additionally, NIC statistics for vmnicX show no valid values — all counters are 0 — indicating no traffic is being passed.

Environment

ESXi 8.0

Cause

The issue is caused by a misconfiguration of LACP on the physical network.

Resolution

Verify the physical network configuration:

• Ensure LACP is correctly configured on both ESXi and the peer physical switch.

• Check the operational status of the corresponding physical switch interfaces and confirm that they are up and correctly participating in the LACP group.