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Tomas Vondra <vondra at ...> writes:

> The setup has 3 network nodes and 1 compute node currently hosting a virtual
> network (GRE based). DVR is enabled. I have just added IPv6 to this network
> and to the external network (VLAN based). The virtual network is set to SLAAC.
> 
> However, the link-local router address and associated MAC address is the
> same in all 4 qr namespaces. About 16% packets get lost in randomly occuring
> bursts. Openvswitch forwarding tables are flapping and I think that the
> packet loss occurs at the moment when all 4 switches learn the MAC address
> through a GRE tunnel simultaneously.

I'm convinced it is a bug that was probably not fixed yet. Filing bug report.
https://bugs.launchpad.net/neutron/+bug/1596473
Tomas