On 2012-03-19 15.00, Dave McGuire wrote: On 03/19/2012 05:57 PM, Mark Wickens wrote: Sorry for being ignorant, what's GRE? It's not ignorance if you've had no reason to know about it. :-) Generic Routing Encapsulation, a Cisco protocol that implements generalized tunneling. You can tunnel just about anything over GRE. Most OSs implement GRE natively nowadays as well. Ah, and rereading the stuff right now reminds me of why I never got anywhere with it. I can't seem to understand how you use it for non-IP traffic. Even reading the Wikipedia article, it says: "A GRE tunnel is used when IP packets need to be sent from one network to another, without being parsed or treated like IP packets by any intervening routers." So, it is essentially for IP traffic. It don't seem to be generic enough for any random ethernet traffic. Then, of course, you can run any kind of traffic on top of that IP layer in the GRE tunnel, and it will all be invisible to the outside. But that don't help when there is no IP to start with... I'll happily go on talking with people interested in this more, but we might do it outside of this list, since it will quickly become pretty narrow and technical. Johnny