Intermittent NIC flapping on ESXi hosts

Products

• VMware vSphere ESXi

Issue/Introduction

Under some circumstances:

• The NIC driver/firmware may report to ESX that the link is going up and down multiple times in a succession. This is known as flapping.
• ESX will code these events based on what is being reported to it as Criteria Codes.

There will be log entries similar to:

• 2025-01-23T01:23:45.678Z In(14) vobd[1234567]  [netCorrelator] 1234567891234us: [vob.net.dvport.uplink.transition.down] Uplink: vmnic# is down. Affected dvPort: ###/## ## ## ## ## ## ## ## ## ## ## ##. 0 uplinks up. Failed criteria: 128
• As these codes are cumulative, there may be other numbers added, for instance Failed criteria 130

Environment

VMware vSphere ESX

Cause

When the link state of a vmnic is detected to be down:

• ESX is not involved in the quality of the link formed between the NIC and the upstream device it is connected to. That connection is negotiated and managed by the NIC's driver/firmware and the upstream device. ESX only logs what the NIC's driver/firmware reports to the ESX Hypervisor to help identify any issues.

Resolution

Please see the following article that covers this issue:

• https://knowledge.broadcom.com/external/article/318898/network-adapter-vmnic-is-down-or-fails-w.html