IPv6 subnet creation in segmented network partially fails

[Carlos Goncalves]

Creation of an IPv6 subnet in a segmented network partially fails. Neutron returns HTTP 400 but subnet record is created and shows up in subnet list.

Master OpenStack deployment (OVN TripleO-based):
  - neutron a1e74ac
  - neutron-lib: 307b6be
  - neutronclient: 4963c7a
  - OVN: 2.13-20.09.0-17.el8.x86_64

$ openstack --os-cloud overcloud subnet create --network multi-segment-provider --network-segment segment-r2 --subnet-range 2001:db8:0:2::/64 --ip-version 6 --ipv6-address-mode=slaac --ipv6-ra-mode=slaac subnet-segment-2-ipv6
BadRequestException: 400: Client Error for url: http://99.88.88.88:9696/v2.0/subnets, Invalid input for operation: Failed to create port on network e1503814-f257-4ccb-bb96-15337a345f77, because fixed_ips included invalid subnet fcdb0a79-b
d40-45d3-b0ee-8fa820c1b3e1.

$ openstack subnet list
+--------------------------------------+-----------------------+--------------------------------------+-------------------+
| ID | Name | Network | Subnet |
+--------------------------------------+-----------------------+--------------------------------------+-------------------+
| 19a5dc8a-897d-45b3-8384-97c1566f69b7 | private-subnet | 2b78aa5a-7a70-489a-a2d6-82b31f77b279 | 10.0.0.0/24 |
| 789c1e83-a3cd-4e01-ae98-286dc5c40d1a | subnet-segment-3 | e1503814-f257-4ccb-bb96-15337a345f77 | 172.24.3.0/24 |
| eada0504-71cd-424f-8ca9-cca2b925fb6d | subnet-segment-2 | e1503814-f257-4ccb-bb96-15337a345f77 | 172.24.2.0/24 |
| fcdb0a79-bd40-45d3-b0ee-8fa820c1b3e1 | subnet-segment-2-ipv6 | e1503814-f257-4ccb-bb96-15337a345f77 | 2001:db8:0:2::/64 |
+--------------------------------------+-----------------------+--------------------------------------+-------------------+

$ openstack subnet show subnet-segment-2-ipv6
+----------------------+--------------------------------------------------+
| Field | Value |
+----------------------+--------------------------------------------------+
| allocation_pools | 2001:db8:0:2::1-2001:db8:0:2:ffff:ffff:ffff:ffff |
| cidr | 2001:db8:0:2::/64 |
| created_at | 2021-02-02T10:47:54Z |
| description | |
| dns_nameservers | |
| dns_publish_fixed_ip | None |
| enable_dhcp | True |
| gateway_ip | 2001:db8:0:2:: |
| host_routes | |
| id | fcdb0a79-bd40-45d3-b0ee-8fa820c1b3e1 |
| ip_version | 6 |
| ipv6_address_mode | slaac |
| ipv6_ra_mode | slaac |
| name | subnet-segment-2-ipv6 |
| network_id | e1503814-f257-4ccb-bb96-15337a345f77 |
| prefix_length | None |
| project_id | 10a643f5ca8a4667b8c7de126c312fc3 |
| revision_number | 0 |
| segment_id | c6008184-3e32-4fbd-a413-e588a9c1249d |
| service_types | None |
| subnetpool_id | None |
| tags | |
| updated_at | 2021-02-02T10:47:54Z |
+----------------------+--------------------------------------------------+

$ openstack network segment show segment-r2
+------------------+--------------------------------------+
| Field | Value |
+------------------+--------------------------------------+
| description | |
| id | c6008184-3e32-4fbd-a413-e588a9c1249d |
| name | segment-r2 |
| network_id | e1503814-f257-4ccb-bb96-15337a345f77 |
| network_type | flat |
| physical_network | r2 |
| segmentation_id | None |
+------------------+--------------------------------------+

2021-02-02 10:47:34.823 30 INFO neutron.wsgi [-] 99.99.2.1 "GET / HTTP/1.1" status: 200 len: 227 time: 0.0046539
2021-02-02 10:47:48.333 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_for_fragmentation_support' _process_scheduled /usr/lib/py
thon3.6/site-packages/futurist/periodics.py:642
2021-02-02 10:47:48.335 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_for_ha_chassis_group_address' _process_scheduled /usr/lib
/python3.6/site-packages/futurist/periodics.py:642
2021-02-02 10:47:48.335 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_for_igmp_snoop_support' _process_scheduled /usr/lib/pytho
n3.6/site-packages/futurist/periodics.py:642
2021-02-02 10:47:48.336 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_for_localnet_legacy_port_name' _process_scheduled /usr/li
b/python3.6/site-packages/futurist/periodics.py:642
2021-02-02 10:47:48.336 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_for_port_security_unknown_address' _process_scheduled /us
r/lib/python3.6/site-packages/futurist/periodics.py:642
2021-02-02 10:47:48.336 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_global_dhcp_opts' _process_scheduled /usr/lib/python3.6/s
ite-packages/futurist/periodics.py:642
2021-02-02 10:47:48.886 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.DBInconsistenciesPeriodics.check_for_inconsistencies' _process_scheduled /usr/lib/python3.
6/site-packages/futurist/periodics.py:642
2021-02-02 10:47:51.224 33 DEBUG futurist.periodics [-] Submitting periodic callback 'neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance.HashRingHealthCheckPeriodics.touch_hash_ring_nodes' _process_scheduled /usr/lib/python3.6/
site-packages/futurist/periodics.py:642
2021-02-02 10:47:54.618 29 DEBUG neutron.pecan_wsgi.hooks.policy_enforcement [req-e396b5c0-32a3-486e-9bae-3450a861b6f8 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Attributes excluded by policy engi
ne: ['standard_attr_id', 'vlan_transparent', 'dns_domain'] _exclude_attributes_by_policy /usr/lib/python3.6/site-packages/neutron/pecan_wsgi/hooks/policy_enforcement.py:256
2021-02-02 10:47:54.620 29 INFO neutron.wsgi [req-e396b5c0-32a3-486e-9bae-3450a861b6f8 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] 99.99.2.1 "GET /v2.0/networks/e1503814-f257-4ccb-bb96-15337a345f77
 HTTP/1.1" status: 200 len: 1160 time: 0.2195470
2021-02-02 10:47:54.701 29 DEBUG neutron.api.v2.base [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Request body: {'subnet': {'ipv6_address_mode': 'slaac', 'i
p_version': 6, 'cidr': '2001:db8:0:2::/64', 'name': 'subnet-segment-2-ipv6', 'segment_id': 'c6008184-3e32-4fbd-a413-e588a9c1249d', 'ipv6_ra_mode': 'slaac', 'network_id': 'e1503814-f257-4ccb-bb96-15337a345f77'}} prepare_request_body /usr/lib/python3.6/site-packages/neutron/api/v2/base.py:729
2021-02-02 10:47:54.710 29 DEBUG neutron.db.quota.driver [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Resources trunk,subnetpool have unlimited quota limit. It is not required to calculate headroom make_reservation /usr/lib/python3.6/site-packages/neutron/db/quota/driver.py:221
2021-02-02 10:47:54.733 29 DEBUG neutron.db.quota.driver [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Attempting to reserve 1 items for resource subnet. Tot
al usage: 3; quota limit: 100; headroom:97 make_reservation /usr/lib/python3.6/site-packages/neutron/db/quota/driver.py:253
2021-02-02 10:47:54.746 29 DEBUG neutron.pecan_wsgi.hooks.quota_enforcement [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Made reservation on behalf of 10a64
3f5ca8a4667b8c7de126c312fc3 for: {'subnet': 1} before /usr/lib/python3.6/site-packages/neutron/pecan_wsgi/hooks/quota_enforcement.py:55
2021-02-02 10:47:54.751 29 DEBUG neutron_lib.callbacks.manager [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Notify callbacks ['neutron.services.segments.plu
gin.SegmentHostRoutes.host_routes_before_create-27042243'] for subnet, before_create _notify_loop /usr/lib/python3.6/site-packages/neutron_lib/callbacks/manager.py:193
2021-02-02 10:47:55.000 29 DEBUG neutron.db.ovn_revision_numbers_db [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] create_initial_revision uuid=fcdb0a79-bd40-
45d3-b0ee-8fa820c1b3e1, type=subnets, rev=-1 create_initial_revision /usr/lib/python3.6/site-packages/neutron/db/ovn_revision_numbers_db.py:105
2021-02-02 10:47:55.243 29 DEBUG neutron.objects.ports [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Time-cost: Fetching 1 ports in 0 security groups get_obj
ects /usr/lib/python3.6/site-packages/neutron/objects/ports.py:428
2021-02-02 10:47:56.263 29 DEBUG neutron_lib.callbacks.manager [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Notify callbacks [] for router, precommit_update
 _notify_loop /usr/lib/python3.6/site-packages/neutron_lib/callbacks/manager.py:193
 2021-02-02 10:47:56.518 29 DEBUG neutron_lib.callbacks.manager [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] Notify callbacks ['neutron.plugins.ml2.plugin.SecurityGroupDbMixin._ensure_default_security_group_handler--9223372036854117193', 'neutron.services.qos.qos_plugin.QoSPlugin._check_port_for_placement_allocation_change--9223372036854435462'] for port, before_update _notify_loop /usr/lib/python3.6/site-packages/neutron_lib/callbacks/manager.py:193
2021-02-02 10:47:56.744 29 INFO neutron.pecan_wsgi.hooks.translation [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] POST failed (client error): The server could not comply with the request since it is either malformed or otherwise incorrect.
2021-02-02 10:47:56.745 29 DEBUG neutron.pecan_wsgi.hooks.notifier [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] No notification will be sent due to unsuccessful status code: 400 after /usr/lib/python3.6/site-packages/neutron/pecan_wsgi/hooks/notifier.py:79
2021-02-02 10:47:56.771 29 INFO neutron.wsgi [req-7674e6bf-3101-4e75-8dd7-c3b817d77fb1 4bff0c73ebaf4a1da4e17ac0d5cd0e8e 10a643f5ca8a4667b8c7de126c312fc3 - default default] 99.99.2.1 "POST /v2.0/subnets HTTP/1.1" status: 400 len: 434 time: 2.0760760

[Lajos Katona (lajos-katona)]

By the gaps list (https://docs.openstack.org/neutron/latest/ovn/gaps.html) routed provider nets not supported/working with OVN now, there's an RFE for it:
https://bugs.launchpad.net/neutron/+bug/1865889

Not sure which part should be expected to work, perhaps a clean rejection would be better till the RFE finished.

[Bernard Cafarelli (bcafarel)]

That RFE status should be updated soon, it has been mostly complete for a while and just missing the documentation step https://review.opendev.org/c/openstack/neutron/+/743709 (which drops it from OVN gaps).
So it would probably help to get some OVN eyes on it