On Thu, Aug 21, 2008 at 01:49:18PM +0200, Henning Brauer wrote: > * Paul de Weerd <[EMAIL PROTECTED]> [2008-08-21 13:48]: > > On Thu, Aug 21, 2008 at 09:50:35AM +0000, Stuart Henderson wrote: > > | > you can stack vlans. aka > > | > > > | > ifconfig vlan2 vlan 2 vlandev em0 > > | > ifconfig vlan4 vlan 4 vlandev vlan2 > > | > > > | > > | I think you have to take a hit on MTU, so this is probably better > > | on gigabit interfaces that are configured for jumbo frames (using > > | ifconfig to increase MTU configures them for jumbos). > > | > > | Cisco does something similar (qinq) but iirc they use a different > > | ethertype, so it may not be directly compatible. > > > > The standard specifies 0x88a8 for 'qinq' or 'stacked vlans' or > > 802.1ad (Provider Bridges). OpenBSD uses 0x8100 for both the outer and > > the inner ethertype (which may give interoperability issues with other > > vendors, don't know, don't have gear that supports it). > > > > Attached is a patch that adds ETHERTYPE_8021AD to ethertypes.h. > > no point in just doing that. > > a button to change the ether type would make sense. >
If we stack vlan interfaces I don't see a real need for such a button. This could be figured out either at configuration time or on runtime. E.g. just check if the ethertype is 0x8100 and add the next vlan tag as 0x88a8. This would also allow to use a bridge for qinq setups. Because of this I think doing it on runtime is the best. -- :wq Claudio
