To setup a VLAN sensor in a VMware ESX environment you will need to make sure there's a trunk available inside your VM. Here's the steps to follow to setup a trunk interface.
Go to Configuration → Networking. Click on “Add Networking”.
Select Virtual Machine.
To make a trunk interface you need to enter the number 4095 as VLAN ID.
Now we have added the trunk interface to vSwitch1. Now click on the properties of vSwitch1.
Go to the Security tab and tick the checkbox for Promiscuous Mode. Make sure the dropdown box is set to “Accept”.