netdev - Re: [BUG] bonded interfaces drop bpdu (stp) frames

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Date:   Wed, 11 Jul 2018 16:22:02 -0700
From:   Mahesh Bandewar (महेश बंडेवार) 
        <maheshb@...gle.com>
To:     Michal Soltys <soltys@....info>
Cc:     linux-netdev <netdev@...r.kernel.org>
Subject: Re: [BUG] bonded interfaces drop bpdu (stp) frames

On Wed, Jul 11, 2018 at 3:23 PM, Michal Soltys <soltys@....info> wrote:
>
> Hi,
>
> As weird as that sounds, this is what I observed today after bumping
> kernel version. I have a setup where 2 bonds are attached to linux
> bridge and physically are connected to two switches doing MSTP (and
> linux bridge is just passing them).
>
> Initially I suspected some changes related to bridge code - but quick
> peek at the code showed nothing suspicious - and the part of it that
> explicitly passes stp frames if stp is not enabled has seen little
> changes (e.g. per-port group_fwd_mask added recently). Furthermore - if
> regular non-bonded interfaces are attached everything works fine.
>
> Just to be sure I detached the bond (802.3ad mode) and checked it with
> simple tcpdump (ether proto \\stp) - and indeed no hello packets were
> there (with them being present just fine on active enslaved interface,
> or on the bond device in earlier kernels).
>
> If time permits I'll bisect tommorow to pinpoint the commit, but from
> quick todays test - 4.9.x is working fine, while 4.16.16 (tested on
> debian) and 4.17.3 (tested on archlinux) are failing.
>
> Unless this is already a known issue (or you have any suggestions what
> could be responsible).
>
I believe these are link-local-multicast messages and sometime back a
change went into to not pass those frames to the bonding master. This
could be the side effect of that.