Current Series Release Notes¶

5.2.1-4¶

Tap devices created by the Open vSwitch plugin (when Neutron requests ovs_create_tap) now have IPv6 disabled before they are brought up. The tap is given the instance’s MAC address, so with IPv6 enabled the host derived the instance’s own link-local address for it and ran duplicate address detection for that address; the resulting neighbour solicitation was queued towards the guest, whose own duplicate address detection could then mark its link-local address dadfailed and leave IPv6 on that interface unusable.

This disables only the host’s IPv6 stack on the tap, not IPv6 traffic forwarded to or from the instance. Guest IPv6 remains enabled. The fix applies to newly created tap devices; existing devices are not reconfigured until recreated through the normal instance lifecycle.