linux-kernel - Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation

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Date:   Thu, 8 Dec 2022 18:09:42 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     netdev@...io-technology.com
Cc:     Ido Schimmel <idosch@...sch.org>, davem@...emloft.net,
        kuba@...nel.org, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB
 implementation

On Thu, Dec 08, 2022 at 05:03:59PM +0100, netdev@...io-technology.com wrote:
> At leisure, do you have an idea why it will encounter a VTU miss violation
> at random?

Do you understand that any packets with a VID that isn't present in the
VTU will trigger a VTU miss, and also an ATU miss if the port is locked
and the ATU doesn't have an entry with that FID?

Your selftest creates a VLAN interface on top of $h1 with a VID that
isn't present in the VTU of the switch ("bridge vlan add .. vid 100" is
run elsewhere; we run "bridge vlan del ... vid 100" when we no longer
need it). But the $h1.100 interface is persistent across the selftest.
And it's not silent. Linux does all sorts of crap by default, like IPv6
neighbor discovery, even if you don't use the interface. So it will send
packets from time to time. And that's when you get those ATU and VTU
violations. The MAC address of $h1.100 is the same as the MAC address of
$h1, of course.