"Dampened freeze state" messages observed for the mac address <##:##:##:##:##.##> reported by monitoring tool; One or more VM's lost communication.

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

• One or more VMs lost connectivity over the network.
• Error message received on monitoring tool.

  • <Date> mac <##:##:##:##:##:##> <log path> total num of ipv4 1 total num of ipv6 0 is in dampened freeze state.

• A dampened freeze state refers to a situation where a Virtual Machine or a Network Endpoint has been temporarily "frozen" or suspended.
• Dampened freeze state messages observed for the mac address <##:##:##:##:##.##>, indicates that the mac is received at both the interfaces of the physical switch.

Environment

VMware vSphere ESXi.
VMware vCenter Server.

Cause

The issue is originating at the physical switch level, where the same MAC address is being learned across two different switch port interfaces, causing a MAC flap.

Resolution

Engage the physical networking team to investigate the physical layer.
We have confirmed that the vSphere layer is not the source of the issue, as the specific MAC address is correctly egressing through a single uplink.

• Perform the packet captures using Packet capture on ESXi using the pktcap-uw tool at both the active interfaces(vmnic# & vmnic#) to see the traffic being sent through single uplink.