netdev - Re: feature request for kernel module 8021q

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Message-ID: <A4D84B7F-5D4A-44C8-875C-C113D7C5C688@gmail.com>
Date:   Thu, 14 Sep 2017 15:16:32 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Pierre Colombier <pierre@...ille.com>, netdev@...r.kernel.org
Subject: Re: feature request for kernel module 8021q

On September 14, 2017 12:14:04 PM PDT, Pierre Colombier <pierre@...ille.com> wrote:
>Hello
>
>
>One big problem with vlans on linux is that the native interface always
>
>get all vlans.
>
>This can cause problem with bridges.

What specific problem are you thinking about?

>
>
>One interesting feature would be to have a special vlan number
>
>(let's say 0 or -1 or 4097 ) designed so that it gets all the untagged 
>trafic and only the untagged trafic.

4097 is not a valid number nor is -1 since that closely follows what the VLAN ID extracted from the tag would be. VLAN 0 is more or less the untagged VLAN.

>
>what do you think about this ?

Provided the HW supports it, with two netdevice operations: ndo_rx_vlan_add_vid and ndo_rx_vlan_kill_vid you can have your HW filter out the VLAN tags it wishes to receive, respectively not receive anymore. If your device does not support that, then yes if you send frames with a VLAN tag for which you are not interested in processing, you are still receiving it unless there is a switch or any kind of VLAN filtering device in between.

Bridge has also gained a VLAN filtering that can also be used to only the reception/transmission of desired VLAN tags. And it also allows you to define the default VLAN tag (VID1) 

-- 
Florian