[ovs-dev] [PATCHv4] tunnel: Add layer 2 IPv6 GRE encapsulation support.

[William Tu]

On Wed, Jun 26, 2019 at 11:31 PM Eli Britstein <elibr at mellanox.com> wrote:
>
>
> On 6/27/2019 1:21 AM, 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 <u9012063 at gmail.com>
> >>> Signed-off-by: Eli Britstein <elibr at mellanox.com>
> >>> Co-authored-by: Eli Britstein <elibr at mellanox.com>
> >>> Tested-by: Greg Rose <gvrose8192 at gmail.com>
> >>> Reviewed-by: Greg Rose <gvrose8192 at gmail.com>
> >> 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.
> >
> > Thanks,
> >
> > - Greg
> >
> >>    That is,
> >> why not just have an "ip6gre" type and then use options:packet_type to
> >> control what packets flow through it?
> >>
> >> (Actually, is there a reason why we should have a separate ip6gre at
> >> all?  That is, why not just use "gre" and then control whether the outer
> >> protocol is IPv4 or IPv6 based on whether the local and remote IPs are
> >> IPv4 or IPv6?)
>
> Hi Ben,
>
> I had a similar comment in
> https://mail.openvswitch.org/pipermail/ovs-dev/2019-June/359940.html
>
> The pro points are clear. The cons are that there are already
> "ip6erspan" separately from "erspan" (unless we do the same work to
> unite them too). Regarding "ip6gre" vs "ip6gretap", I thought it might
> be confusing as the type of the netdev is "ip6gretap" (for L2) and there
> is "ip6gre" type for L3. In IPv4 case, it is like this too
> ("gre"/"gretap", but there is support for both, so "gre" is more user
> friendly). In IPv6 case, as William and Greg commented, L3 over IPv6 GRE
> is not supported (at least yet).
>

Or do we want to add support for ip6gre (L3)?
So we can use "ip6gre" and packet_type option to select L2 or L3.
--William