On 2016/03/15 23:34, David Gwynne wrote:
> Can you find any doco that states that? Or any other thing that does it?

IEEE 802.1Q-2014 (https://standards.ieee.org/about/get/802/802.1.html)
section 9.6 (on p160):

0   The null VID. Indicates that the tag header contains only priority
information; no VID is present in the frame. This VID value shall not be
configured as a PVID or a member of a VID Set, or configured in any FDB
entry, or used in any Management

> On 15 Mar 2016 02:21, "Stuart Henderson" <[email protected]> wrote:
> 
> > On 2016/03/14 21:13, David Gwynne wrote:
> > > this adds macros to describe the min and max valid vlan ids.
> > >
> > > this will be used in upcoming checks of the configured values from
> > > userland.
> > >
> > > ok?
> >
> > Hmm - I think there may be something about using tag 0 to allow
> > sending packets on an "untagged" vlan with .1q priorities ..
> >
> > > Index: if_ether.h
> > > ===================================================================
> > > RCS file: /cvs/src/sys/netinet/if_ether.h,v
> > > retrieving revision 1.68
> > > diff -u -p -r1.68 if_ether.h
> > > --- if_ether.h        14 Mar 2016 03:48:47 -0000      1.68
> > > +++ if_ether.h        14 Mar 2016 11:12:24 -0000
> > > @@ -87,7 +87,11 @@ struct  ether_vlan_header {
> > >          u_int16_t evl_proto;
> > >  };
> > >
> > > -#define EVL_VLID_MASK   0x0FFF
> > > +#define EVL_VLID_MASK        0xFFF
> > > +#define EVL_VLID_NONE        0x000
> > > +/* 0x000 and 0xfff are reserved */
> > > +#define EVL_VLID_MIN 0x001
> > > +#define EVL_VLID_MAX 0xFFE
> > >  #define EVL_VLANOFTAG(tag) ((tag) & EVL_VLID_MASK)
> > >
> > >  #define EVL_PRIO_MAX    7
> > >
> >

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