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From:   Vladimir Oltean <olteanv@gmail.com>
Date:   Tue, 26 May 2020 21:25:45 +0300
Message-ID: <CA+h21hp+khuj0jV9+keDuzPDe11Xz1Rs8KKkt=n8MeWVHkcmvQ@mail.gmail.com>
Subject: Re: [net-next RFC PATCH 00/13] net: hsr: Add PRP driver
To:     Murali Karicheri <m-karicheri2@ti.com>
Cc:     Vinicius Costa Gomes <vinicius.gomes@intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>, linux-api@vger.kernel.org,
        Sekhar Nori <nsekhar@ti.com>,
        Grygorii Strashko <grygorii.strashko@ti.com>
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Hi Murali,

On Tue, 26 May 2020 at 17:12, Murali Karicheri <m-karicheri2@ti.com> wrote:
>
> Hi Vladimir,
>

> I haven't looked the spec for 802.1CB. If they re-use HSR/PRP Tag in the
> L2 protocol it make sense to enhance the driver. Else I don't see any
> re-use possibility. Do you know the above?
>
> Thanks
>
> Murali

IEEE 802.1CB redundancy tag sits between Source MAC address and
Ethertype or any VLAN tag, is 6 bytes in length, of which:
- first 2 bytes are the 0xf1c1 EtherType
- next 2 bytes are reserved
- last 2 bytes are the sequence number
There is also a pre-standard version of the IEEE 802.1CB redundancy
tag, which is only 4 bytes in length. I assume vendors of pre-standard
equipment will want to have support for this 4-byte tag as well, as
well as a mechanism of converting between HSR/PRP/pre-standard 802.1CB
tag on one set of ports, and 802.1CB on another set of ports.

>
> --
> Murali Karicheri
> Texas Instruments

Thanks,
-Vladimir