Proxy VM communication degraded when migrated to specific hosts.

Products

• VMware vSphere ESXi

Issue/Introduction

•  Proxy VM communication degraded when migrated to specific hosts.
• The customized proxy VM requires promiscuous configuration on the port group/vSwitch.

Environment

VMware ESX

Cause

• In a NIC teamed environment where multiple uplinks are configured for a virtual switch, and a port channel or LACP is not configured on the physical switch, the vSwitch will receive a multicast or broadcast packet from the physical network on each vSwitch uplink in the NIC team.  
• All traffic received by the vSwitch will be forwarded to the virtual port group in promiscuous mode, so the virtual machine guest OS will receive multiple multicast or broadcast packets.

Resolution

 /Net/ReversePathFwdCheckPromisc has to be enabled to discard packets coming from uplinks that are not associated with the particular client when promiscuous mode is enabled.
 This will prevent duplicate packets from being received by the guest operating system.  
 
 To Enable From the UI

 Inventory -> Host -> System -> Advanced System Settings -> Edit -> Filter - Key "ReversePathFwdCheckPromisc" and Set the Value "1"

To Enable From the CLI.

  esxcli system settings advanced set -o /Net/ReversePathFwdCheckPromisc -i 1
  
 How to check the configuration
 
  esxcli system settings advanced list -o /Net/ReversePathFwdCheckPromisc

Additional Information

 https://knowledge.broadcom.com/external/article/324553 
 https://knowledge.broadcom.com/external/article/329011