>> The bge(4) manpage says, vlans are not supported on bge(4)
>> interfaces.

>> From what I tried, I'd say: it basically works.  I have connected a
>> cisco 802.1q trunk port to my notebook and sucessfully created
>> several vlan interfaces to my physical bge interface.

Yes, but you had problems that look like exactly what I'd expect.

Vlan support depends on the ethernet handling slightly oversize
packets; the only plausible reason why an Ethernet interface wouldn't
be able to handle vlans is that it can't do oversize packets.
(Everything else about vlans is a host software issue.)  I note your
test fails on exactly when packets start being full-size, ie, when the
vlan-encapsulated packet is oversize.

You might try setting the interface's MTU down slightly, though you
will have all the problems associated with low-MTU links and may have
to set the MTU down slightly on other hosts on the Ethernet too
(especially your default gateway).

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