When is promiscuous mode actually needed?

[afhelton]

I've been reading up on how to enable access to other server existing behind my configured OpenVPN server. In the Community Resources doc about how to do this (https://openvpn.net/community-resources ... er-subnet/), it mentions enabling IP Forwarding. I've gone in and made the appropriate registry change & have enabled the Routing and Remote Access Service (is this necessary? - I have been unable to determine if it is), however, in various places it also mentions that it's necessary to enable promiscuous mode on the NIC. I currently have a working configuration and have not enabled promiscuous mode, so I am wondering when it is necessary to do so. Is this something that only applies if you are implementing Ethernet Bridging?