Frederik Deweerdt wrote: > On Fri, Jun 16, 2006 at 01:12:06PM +0100, Alex Zeffertt wrote: >>>> Another possible problem: what if you are trying to encapsulate vlan 7 inside >>>> of vlan 7. How do you know to double-encapsulate? What if user-space is sending >>>> a pre-built VLAN frame with a raw socket? I'm not sure there is enough info as to >>>> the intent to encapsulate or not once the VLAN code receives the packet. >>> I see how my proposal was wrong. Let me wild guess again :). I wondered if the following >>> code could be better. The idea being that the code could determine the need for >>> encapsulating or not from the interface's nesting level and the actual number of VLAN tags in the packet. >> >> >> I think we've had this conversation before. Search the list archives for "vlan Q in Q" > Thanks for the pointer. Do you know why your patch didn't get merged into mainline? > A couple of reasons. Firstly the patch means that the REORDER_HEADER flag (which is set by default) cannot be unset. Unsetting this flag provides a slight performance enhancement when bridging between two interfaces and keeping the same tag. Secondly, the current code allows you to send either untagged or tagged frames to a raw socket and the result is the same, a tagged frame is sent. The patch however, always adds a tag irrespective of whether the frame was already tagged. (This functionality *had* to be ditched because if you allow q-in-q then you may *want* your frame double tagged.) IMHO, raw sockets *should* always tag, rather than tag or not tag depending on whether the frame is already tagged. It just seems more logical and consistent. Ciao, Alex
