Re: [PATCH RFC 0/7] net: bridge: cfm: Add support for Connectivity Fault Management(CFM)

[Allan W. Nielsen]

Hi,

On 08.09.2020 11:04, Henrik Bjoernlund - M31679 wrote:
> > On Sun, 2020-09-06 at 20:21 +0200, Horatiu Vultur wrote:
> > > The 09/04/2020 15:44, Stephen Hemminger wrote:
> > > > On Fri, 4 Sep 2020 09:15:20 +0000 Henrik Bjoernlund
> > > > <henrik.bjoernlund@xxxxxxxxxxxxx> wrote:
> > Hi, I also had the same initial thought - this really doesn't seem to
> > affect the bridge in any way, it's only collecting and transmitting
> > information. I get that you'd like to use the bridge as a passthrough
> > device to switchdev to program your hw, could you share what would be
> > offloaded more specifically ?
> Yes.
>
> The HW will offload the periodic sending of CCM frames, and the
> reception.
>
> If CCM frames are not received as expected, it will raise an interrupt.
>
> This means that all the functionality provided in this series will be
> offloaded to HW.
>
> The offloading is very important on our HW where we have a small CPU,
> serving many ports, with a high frequency of CFM frames.
>
> The HW also support Link-Trace and Loop-back, which we may come back to
> later.
>
> > All you do - snooping and blocking these packets can easily be done
> > from user- space with the help of ebtables, but since we need to have
> > a software implementation/fallback of anything being offloaded via
> > switchdev we might need this after all, I'd just prefer to push as
> > much as possible to user-space.
In addition to Henriks comment, it is worth mentioning that we are
trying to push as much of the functionallity to user-space (learnings
from the MRP discussions).

This is why there are currently no in-kernel users of the CCM-lose
singnal. When a CCM-defect is happening the network typically needs to
be re-configured. This we are trying to keep in user-space.

> > I plan to review the individual patches tomorrow.
Thanks.

/Allan