[ovs-discuss] GRE with link-local remote_ip: "not a valid IPv6 address"

Ben Pfaff blp at ovn.org
Wed Aug 28 17:26:30 UTC 2019

On Tue, Aug 27, 2019 at 12:09:14PM +0200, Sven Gebauer wrote:
> Hi all,
> I'm trying to create a GRE tunnel with an IPv6 link-local address as the
> remote_ip. According to the changelog, this should be supported since
> v2.8.0. However...

IPv6 link-local addresses are supported for use in contexts where OVS is
creating a socket, most notably for connections to controllers.  In
other contexts, there's nowhere for OVS to put the scope, so it can't
support it.  In this case, the kernel flow structure doesn't have a
scope in it, so there's nothing that userspace OVS can do about it.  If
this feature were to be added, it would require adding the scope
(probably in multiple places) to that kernel flow structure, which would
probably be difficult for reasons of backward compatibility and
coordination with (and justification to) the kernel network stack

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