netdev - Re: [PATCH net-next v1] net: dsa: mv88e6xxx: Trap PTP traffic

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Date:   Sun, 12 Dec 2021 16:16:58 +0100
From:   Kurt Kanzenbach <kurt@...-computers.de>
To:     Richard Cochran <richardcochran@...il.com>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Tobias Waldekranz <tobias@...dekranz.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v1] net: dsa: mv88e6xxx: Trap PTP traffic

On Sat Dec 11 2021, Richard Cochran wrote:
> On Fri, Dec 10, 2021 at 09:14:10PM -0800, Jakub Kicinski wrote:
>> On Fri, 10 Dec 2021 01:07:59 +0100 Tobias Waldekranz wrote:
>> > Do we know how PTP is supposed to work in relation to things like STP?
>> > I.e should you be able to run PTP over a link that is currently in
>> > blocking?
>> 
>> Not sure if I'm missing the real question but IIRC the standard
>> calls out that PTP clock distribution tree can be different that
>> the STP tree, ergo PTP ignores STP forwarding state.
>
> That is correct.  The PTP will form its own spanning tree, and that
> might be different than the STP.  In fact, the Layer2 PTP messages
> have special MAC addresses that are supposed to be sent
> unconditionally, even over blocked ports.

Thanks for clarification. This needs fixing in hellcreek too, as
pass_blocked is currently not set for the ptp fdb entries.

Thanks,
Kurt