VMs are not consistently accessible on the network when RSPAN is enabled

Products

• VMware vSphere ESXi

Issue/Introduction

• RSPAN is enabled on the physical switch 
• Complex physical switched environment
• Pings failing for VMs (virtual machines) when physical switch RSPAN is enabled to monitor traffic

Environment

esxi 8.x

Cause

Physical switch is looping back MAC addresses when RSPAN is enabled on the physical switch due to configuration line, "switchport hybrid allowed-vlan all". Network traffic forwarding fails due to the MAC addresses being seen (learned) on multiple switchport ports.

Resolution

Disable RSPAN or remove physical switch configuration "switchport hybrid allowed-vlan all".

Note: Contact the physical switch hardware vendor for assistance and guidance.