vlan id 0

[Danny J. Mitzel]

  On Sat, Sep 27, 2014 at 4:44 PM, Adrian Chadd wrote:
  > .. the spec allows vlan id=0?

0 is not a valid VLAN ID but the specs do allow it
in a tagged packet, it's called "Priority tagged".
The priority bits should be interpreted when making
any queuing / scheduling decisions during forwarding.
The VLAN ID bits are ignored and packet is to be
treated as untagged during forwarding / flooding
decisions.