VMware ESXi host network flapping error when Beacon Probing is selected

Products

• VMware vSphere ESXi

Issue/Introduction

• Cisco network switch reports this error:

Log Buffer (4096 bytes):
Jul 22 12:18:49.491: %SW_MATM-4-MACFLAP_NOTIF: Host ####.####.#### in vlan 3 is flapping between port Gi0/2 and port Gi0/5
Jul 22 12:18:54.499: %SW_MATM-4-MACFLAP_NOTIF: Host ####.####.#### in vlan 11 is flapping between port Gi0/7 and port Gi0/11
Jul 22 12:18:55.136: %SW_MATM-4-MACFLAP_NOTIF: Host ####.####.#### in vlan 11 is flapping between port Gi0/12 and port Gi0/8
Jul 22 12:19:04.481: %SW_MATM-4-MACFLAP_NOTIF: Host ####.####.#### in vlan 3 is flapping between port Gi0/1 and port Gi0/

• Connectivity issues within the ESXi infrastructure for anything on the vSwitch or portgroup configured with Beacon Probing, such as iSCSI Storage, VMs, vCenter, etc.

Environment

VMware vSphere ESXi

Cause

This issue occurs when Beacon Probing is enabled with EtherChannel.

A flapping error occurs when the same MAC address is detected from two different physical ports. This can happen, for example, if two physical ports are connected to different ESXi hosts.

Resolution

To resolve this issue, ensure that Network Failover detection is set to Link Status Only. Do not use Beacon Probing with IP hash load balancing.

Note: Always use IP hash load balancing with EtherChannel.

For more information, see Sample configuration of EtherChannel / Link aggregation with ESX/ESXi and Cisco/HP switches.

Additional Information

For more information on Beacon Probing, see What is beacon probing?