netdev - Re: Problem with VLANs and via-velocity driver

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Message-ID: <4B0561A6.3020502@trash.net>
Date:	Thu, 19 Nov 2009 16:17:58 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Séguier Régis <rseguier@...eleport.net>
CC:	Kevin Shanahan <kmshanah@...enchant.net>, netdev@...r.kernel.org
Subject: Re: Problem with VLANs and via-velocity driver

Séguier Régis wrote:
> Patrick McHardy a écrit :
>>
>>>> There's some special-casing for VID 0 in velocity_init_cam_filter().
>>>> Does "ip link add link eth0 type vlan id 0" make any difference?
>>>> If not, does "ip link set eth0 promisc on"?
>>>>         
>>> When we patch the driver to support multiple vlan, we decide to use the
>>> vlan 0 to desactivate the vlan filtering.
>>>     
>>
>> Why? The usual behaviour is to receive both tagged and untagged
>> frames.
>>   
> We decide this with françois as an alternative to desactivate the NIC
> vlan filtering instead of creating a modul parameter.
> The vlan id 0 need to be created but not necessary activate.

That doesn't seem like a good idea since it behaves differently than
any other driver supporting VLAN.

> In september 2008, we had a discution about exactly the same problem.
> You speak about the possibility of an ALLVLAN device flag.

That was meant for the case where hardware filtering for specific VLANs
is active and you want to see traffic of VLANs not configured locally
without switching to promiscous mode.

> I think i proposed a patch to desactivate NIC vlan filtering when we are
> in promisc mode but not used.

Yes, in promiscous mode VLAN filtering should be disabled.
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