[PATCH net-next mlxsw] mlxsw: spectrum_span: Support LAG under mirror-to-gretap

[Ido Schimmel]

On Fri, May 11, 2018 at 05:49:26PM +0200, Petr Machata wrote:
> When resolving a path that the packet will take after being encapsulated
> in mirror-to-gretap scenarios, one of the devices en route could be a
> LAG. In that case, mirror to first up slave that corresponds to a front
> panel port.
> 
> Signed-off-by: Petr Machata <petrm at mellanox.com>
> ---
> 
> Notes:
>     Unlike VLANs, we don't support LAG in SPAN and RSPAN situations, only
>     ERSPAN ones. mlxsw can't actually support LAG well--since it needs to
>     resolve the mirroring to a particular front panel port, there's no way
>     to express the load balancing that the LAG is supposed to do.
>     
>     In SPAN and RSPAN scenarios, the decision to set up a certain mirror is
>     purely an administrative one, and a given administrator can always
>     resolve a particular front panel port themselves. For ERSPAN however,
>     while the decision to mirror is administrative, routing of underlay
>     packets is a matter of routing protocols that might just happen to put
>     the remote tunnel end behind a LAG port. For these cases rather than
>     dropping the mirroring altogether, and reinstating it again only when
>     routes change, have mlxsw choose an arbitrary LAG member.

This is useful info. Can I just copy this into the commit message? The
patch looks fine to me otherwise, so I'll apply it now.