[Pkg-libvirt-maintainers] Bug#923249: Bug#923249: libvirt0: libvirt sets disable_ipv6 on bridge, entirely breaking internal IPv6 networking

[Guido Günther]

Hi,
On Mon, Feb 25, 2019 at 04:53:27PM +0100, Ralf Jung wrote:
> Hi again,
> 
> It turns out that setting disable_ipv6=0 is not enough to regain working IPv6:
> Now the RAs from the router arrive at the client, but when the client sends a
> neighbor discovery, it never makes its way to the router, so the client cannot
> actually communicate via IPv6. I can see the ND packages on vnet2 on the host,
> but not on virbr1 (which vnet2 is attached to). Again this is something that
> worked just fine before the update.
> 
> I have no idea what is preventing the ND packages to be forwarded by the bridge.
> I always thought bridges are just switches operating on layer 2, but it seems
> that's as from the truth...

Can you check if downgrading the kernel helps?
 -- Guido