12.3: igb driver does not receive vlan-tagged packets

Hija,

  after swapping network interface card (re0) to igb0, my networking
failed.

I found that igb does send out vlan tagged packets, but not receive
any answers, unless a vlan* device was previousely attached with the
required vlan number (observed with tcpdump).

My current workaround is this hack in rc.conf, which makes things work
again for now (I need vlan 7 only for ISP uplink):

> cloned_interfaces="vlan0"
> ifconfig_vlan0="vlan 7 vlandev igb0"
> ifconfig_vlan0_alias0="destroy"

That vlan0 device is not needed, but it must have existed once after
boot in order to receive the packets at all. This was not the case
with the re0 driver.
Switching off all hw-offload stuff doesn't seem to change the issue.

Is there a rationale for this, or am I missing some neccessary config?
(Not seeing any bugreports or otherwise discussion of the matter)


cheerio,
PMc