IPv6 GUA L2 connectivity (SLAAC) is broken (network wasn't associated with any router, hence VPN)

IPv6 L2 connectivity (SLAAC) is broken

1. neutron net-create N

2. openstack subnet create --network N --subnet-range 2001:db3:0:2::/64 SUB6_3 --ip-version=6 --ipv6-address-mode=slaac --ipv6-ra-mode=slaac --allocation-pool start=2001:db3:0:2::2,end =2001:db3:0:2:ffff:ffff:ffff:fffe

3. neutron security-group-create SG

openstack security group rule create SG --egress --ethertype IPv6 --dst-port 1:65535 --protocol udp
openstack security group rule create SG --inress --ethertype IPv6 --dst-port 1:65535 --protocol udp
openstack security group rule create SG --egress --ethertype IPv6 --dst-port 1:65535 --protocol tcp
openstack security group rule create SG --inress --ethertype IPv6 --dst-port 1:65535 --protocol tcp
openstack security group rule create SG --egress --ethertype IPv6 --protocol icmp
openstack security group rule create SG --inress --ethertype IPv6 --protocol icmp

openstack security group rule create SG --egress --ethertype IPv4 --dst-port 1:65535 --protocol udp
openstack security group rule create SG --inress --ethertype IPv4 --dst-port 1:65535 --protocol udp
openstack security group rule create SG --egress --ethertype IPv4 --dst-port 1:65535 --protocol tcp
openstack security group rule create SG --inress --ethertype IPv4 --dst-port 1:65535 --protocol tcp
openstack security group rule create SG --egress --ethertype IPv4 --protocol icmp
openstack security group rule create SG --inress --ethertype IPv4 --protocol icmp

4. openstack port create --network N PORT1 --security-group SG  --allowed-address ip-address=3001:db8:cafe:d::/64 --allowed-address ip-address=3001:db8:abcd:d::/64

openstack port create --network N PORT2 --security-group SG  --allowed-address ip-address=3001:db8:cafe:d::/64 --allowed-address ip-address=3001:db8:abcd:d::/64

5. openstack server create --image cirros-0.3.4-x86_64-uec --flavor m1.tiny --nic port-id=0c8595f2-8960-44a8-ab14-e50c132e3d83 --security-group SG VM

openstack server create --image cirros-0.3.4-x86_64-uec --flavor m1.tiny --nic port-id=e25ac678-79fb-47ea-8894-1dd88ad0ce12 --security-group SG VM1

Nova shows VMs IPv6 addresses:

root@controller-deray:~# nova list
-------------------------------------------------------------------------------------------------------+

-------------------------------------------------------------------------------------------------------+

but actually VMs do not receive its IPv6 addresses and if we will ping them from N-network qdhcp-namespace, we see, that L2 IPv6 connectivity is broken:

~# ip netns exec qdhcp-deaa20fb-b9c4-470a-b7bf-09dc3b739730 ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
34: tapf738b58d-f2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1408 qdisc noqueue state UNKNOWN group default qlen 1000
link/ether fa:16:3e:0b:e7:d4 brd ff:ff:ff:ff:ff:ff
inet 169.254.169.254/16 brd 169.254.255.255 scope global tapf738b58d-f2
valid_lft forever preferred_lft forever
inet6 2001:db9:0:2:f816:3eff:fe0b:e7d4/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::f816:3eff:fe0b:e7d4/64 scope link
valid_lft forever preferred_lft forever

1. ip netns exec qdhcp-deaa20fb-b9c4-470a-b7bf-09dc3b739730 ping6 2001:db9:0:2:f816:3eff:fe9a:5f0d
   PING 2001:db9:0:2:f816:3eff:fe9a:5f0d(2001:db9:0:2:f816:3eff:fe9a:5f0d) 56 data bytes
   ^C
   • • 2001:db9:0:2:f816:3eff:fe9a:5f0d ping statistics —
       3 packets transmitted, 0 received, 100% packet loss, time 2016ms
2. ip netns exec qdhcp-deaa20fb-b9c4-470a-b7bf-09dc3b739730 ping6 2001:db9:0:2:f816:3eff:fe52:3053
   PING 2001:db9:0:2:f816:3eff:fe52:3053(2001:db9:0:2:f816:3eff:fe52:3053) 56 data bytes
   From 2001:db9:0:2:f816:3eff:fe0b:e7d4 icmp_seq=1 Destination unreachable: Address unreachable
   From 2001:db9:0:2:f816:3eff:fe0b:e7d4 icmp_seq=2 Destination unreachable: Address unreachable
   From 2001:db9:0:2:f816:3eff:fe0b:e7d4 icmp_seq=3 Destination unreachable: Address unreachable
   ^C
   • • 2001:db9:0:2:f816:3eff:fe52:3053 ping statistics —
       4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3015ms

If we reproduce the same steps with IPv4-only, network L2 connectivity works well.

Just to recheck, security-group-rule-list:

~# neutron security-group-rule-list | grep SG
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.