“Really” enabling promiscous mode for vSphere VMs (VMWare KB 59235)

 We had this situation twice now where just enabling promiscous mode on a dvSwitch port group was not sufficient to the application.

There is one setting that need to be enabled as well especially when using more then one uplink (what you should have for redundancy) except when using LACP.

This is documented in following KB

Duplicate Multicast or Broadcast Packets are Received by a Virtual Machine When the Interface is Operating in Promiscuous Mode (59235)

You may set this via PowerCLI to save the hassle for ssh´ing to all needed hosts:

$options = @{option="/Net/ReversePathFwdCheckPromisc";intvalue=1}
$esxcli = get-vmhost "YourHostnameHere" | get-esxcli -v2
$esxcli.system.settings.advanced.set.Invoke($options)