vCenter (VC) or vROps may incorrectly report small packet drops for a Distributed Virtual Switch (DVS) port, even when no actual packet drops occur.

Products

• VMware vSphere ESXi

Issue/Introduction

• In vsish, we do not see dropped packets under vmxnet3 statistics, nor is there any increment in the "droppedRx" counter under overall port statistics.
• Virtual machines migrated to ESXi version 7.0 do not exhibit this false reporting.
• We observe fluctuations in the pktsOutDropped and pktsInDropped counters, which temporarily increase to a non-zero value before returning to zero.

Environment

VMware ESXi 8.0
VMware ESXi 9.0

Cause

This behavior stems from how packet drops are tracked across the network stack, including the vSwitch module. Since some network modules do not track drops directly, the total drop count is calculated by aggregating several counters that cannot be read atomically. This asynchronous reading can lead to false positive reporting of packet drops.

Resolution

While there is no immediate fix, customers who monitor the DVS port statistics graph should follow this guidance:

• Ignore temporary spikes in the drop count.
• A constant, non-zero line indicates actual packet drops.

We plan to redesign how drops are counted in a future release to address the root cause of this inaccurate reporting.