Re: vlan and bpf

Mouse <[email protected]> writes:

>> How to you believe the vlan traffic should appear, in terms of bits
>> in a bpf frame?
>
> I wasn't the one who wrote what you're responding to, but I would
> expect to see it just as it is on the wire (I do consider stripping
> channel seizure and CRC acceptable):
>
> Ethernet destination
> Ethernet MAC
> 0x8100 (ETHERTYPE_VLAN)
> VLAN tag-and-priority
> Encapsulated payload:
>   Inner-layer ETHERTYPE_*
>   Inner-layer payload

I think you have that right.  If that's what was appearing dhcpd would
not have responded to it.

> If you're stuck with hardware that insists on stripping VLAN tags, IMO
> the only sane thing is to synthesize the stripped 4 octets for
> presentation via bpf.

Agreed.  That is what I am starting to think, that the _if_input routine
has to do this.   Except that my impression is that input processing
before the input ifq is doing this anyway, hardware or no, so you
~always have to do this.

I'll read over the code tomorrow.

With my temp/kludge patch, my dhcpd logs look clean