On Thu, Jun 27, 2019 at 9:10 AM Gregory Rose <[email protected]> wrote:
>
>
>
> On 6/27/2019 7:51 AM, Ben Pfaff wrote:
> > On Wed, Jun 26, 2019 at 03:21:49PM -0700, Gregory Rose wrote:
> >> On 6/26/2019 11:59 AM, Ben Pfaff wrote:
> >>> On Wed, Jun 26, 2019 at 08:22:07AM -0700, William Tu wrote:
> >>>> The patch adds ip6gretap support. Tunnel type 'ip6gretap' is a layer 2 
> >>>> GRE
> >>>> tunnel over IPv6, carrying inner ethernet packets and encap with GRE 
> >>>> header
> >>>> with outer IPv6 header.  Encapsulation of layer 3 packet over IPv6 GRE, 
> >>>> ip6gre,
> >>>> is not supported yet.  I tested it by running:
> >>>>     # make check-kernel TESTSUITEFLAGS='-k ip6gretap'
> >>>> under kernel 5.2 and for userspace:
> >>>>     # make check TESTSUITEFLAGS='-k ip6gretap'
> >>>>
> >>>> Signed-off-by: William Tu <[email protected]>
> >>>> Signed-off-by: Eli Britstein <[email protected]>
> >>>> Co-authored-by: Eli Britstein <[email protected]>
> >>>> Tested-by: Greg Rose <[email protected]>
> >>>> Reviewed-by: Greg Rose <[email protected]>
> >>> Thanks for working to generalize OVS tunnel support.
> >>>
> >>> For IPv4 GRE, we use the "gre" tunnel type and then we use
> >>> options:packet_type to control whether the tunnel carries L2 or L3
> >>> packets.  Is there a reason that IPv6 GRE should be different?
> >> Hi Ben,
> >>
> >> unfortunately there is a reason that ipv6 gre is different and that is
> >> because it uses the ARPHRD_IP6GRE HW type.  That
> >> is not currently supported by openvswitch so the best we can do for ipv6 
> >> gre
> >> is support the L2 tap driver which uses
> >> the ARPHRD_ETHER type.
> > I think that this is really an implementation detail.  Ideally, we would
> > abstract the interface provided to our users (the configuration in the
> > database, and the OpenFlow interface) from the implementation in the
> > datapath.  This seems doubly true because I don't know a reason why this
> > detail of the Linux kernel datapath would extend to other datapaths such
> > as the userspace datapath.
>
> I agree - there is a lot we could do to improve the user interface for
> all the gre based tunnels, including
> erspan.  I'll see if I can find some time to work on this.  Adding
> ARPHRD_IP6GRE support to the kernel datapath
> has not been scoped yet (SFAIK) and given all the subtle dependencies
> that developed because our kernel datapath
> has only supported ARPHRD_ETHER in the past I want to express caution.
> But if L3 ip6gre support in the kernel
> datapath is important then we can look at it.
>
> -  Greg
>
Thanks for the feedbacks.

Let me work on v5 to use 'ip6gre' with packet_type = L2,
instead of using 'ip6gretap' and document that L3 ip6gre is
not supported yet. Once we have L3 support, we user interface
can remain the same.

--William
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