openstack/neutron
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Merge "[OVN] Set always the GW LRP "gateway_mtu" option"

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Zuul 2025-01-10 00:27:50 +00:00 committed by Gerrit Code Review
commit 06ab3812be
6 changed files with 105 additions and 30 deletions
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18
doc/source/admin/ovn/routing.rst
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@ -181,3 +181,21 @@ encapsulation) it's been included for completeness.
Traffic goes directly from instance to instance through br-int in the case
of both instances living in the same host (VM1 and VM2), or via
encapsulation when living on different hosts (VM3 and VM4).
Packet fragmentation
~~~~~~~~~~~~~~~~~~~~
The Neutron configuration variable ``[ovn]ovn_emit_need_to_frag`` configures
OVN to emit the "need to frag" packets in case of MTU mismatches. This
configuration option allows Neutron to set, in the router gateway
``Logical_Router_Port``, the option "gateway_mtu". If a packet from any
network reaches the gateway ``Logical_Router_Port``, OVN will send the "need
for frag" message.
In order to allow any E/W or N/S traffic to cross the router, the value of
"gateway_mtu" will have the lowest MTU value off all networks connected to the
router. This could impact the performance of the traffic using the networks
connected to the router if the MTU defined is low. But the user can unset the
Neutron configuration flag in order to avoid the fragmentation, at the cost
of limiting the communication between networks with different MTUs.

19
neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py
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@ -1686,14 +1686,12 @@ class OVNClient:
for net in networks) else 'false'
return reside_redir_ch
def _gen_router_port_options(self, port, network_mtu=None):
def _gen_router_port_options(self, port):
options = {}
admin_context = n_context.get_admin_context()
ls_name = utils.ovn_name(port['network_id'])
ls = self._nb_idl.ls_get(ls_name).execute(check_error=True)
network_type = ls.external_ids[ovn_const.OVN_NETTYPE_EXT_ID_KEY]
network_mtu = network_mtu or int(
ls.external_ids[ovn_const.OVN_NETWORK_MTU_EXT_ID_KEY])
# For provider networks (VLAN, FLAT types) we need to set the
# "reside-on-redirect-chassis" option so the routing for this
# logical router port is centralized in the chassis hosting the
@ -1717,16 +1715,16 @@ class OVNClient:
LOG.debug("Router %s not found", port['device_id'])
else:
network_ids = {port['network_id'] for port in router_ports}
# If this method is called during a port creation, the port
# won't be present yet in the router ports list.
network_ids.add(port['network_id'])
networks = None
if ovn_conf.is_ovn_emit_need_to_frag_enabled():
networks = self._plugin.get_networks(
admin_context, filters={'id': network_ids})
for net in networks:
if net['mtu'] > network_mtu:
options[
ovn_const.OVN_ROUTER_PORT_GW_MTU_OPTION] = str(
network_mtu)
break
# Set the lower MTU of all networks connected to the router
min_mtu = str(min(net['mtu'] for net in networks))
options[ovn_const.OVN_ROUTER_PORT_GW_MTU_OPTION] = min_mtu
if ovn_conf.is_ovn_distributed_floating_ip():
# NOTE(ltomasbo): For VLAN type networks connected through
# the gateway port there is a need to set the redirect-type
@ -2136,8 +2134,7 @@ class OVNClient:
commands = []
for port in ports:
lrp_name = utils.ovn_lrouter_port_name(port['id'])
options = self._gen_router_port_options(
port, network_mtu=prov_net['mtu'])
options = self._gen_router_port_options(port)
# Do not fail for cases where logical router port get deleted
commands.append(self._nb_idl.lrp_set_options(lrp_name,
if_exists=True,

73
neutron/tests/functional/plugins/ml2/drivers/ovn/mech_driver/ovsdb/test_ovn_client.py
View File

@ -223,21 +223,21 @@ class TestOVNClient(base.TestOVNFunctionalBase,
ovn_client.delete_address_group(self.context, ag['id'])
self.assertEqual((None, None), _find_address_set_for_ag())
def _check_gw_lrp_mtu(self, router_id, mtu):
# Find gateway LRP and check the MTU value.
lr = self.nb_api.lookup('Logical_Router',
ovn_utils.ovn_name(router_id))
for lrp in lr.ports:
if strutils.bool_from_string(
lrp.external_ids[
ovn_const.OVN_ROUTER_IS_EXT_GW]):
self.assertEqual(mtu, int(lrp.options['gateway_mtu']))
return
self.fail('Gateway Logical_Router_Port not found for '
'router %s' % router_id)
def test_update_network_lrp_mtu_updated(self):
def check_gw_lrp_mtu(router_id, mtu):
# Find gateway LRP and check the MTU value.
lr = self.nb_api.lookup('Logical_Router',
ovn_utils.ovn_name(router_id))
for lrp in lr.ports:
if strutils.bool_from_string(
lrp.external_ids[
ovn_const.OVN_ROUTER_IS_EXT_GW]):
self.assertEqual(mtu, int(lrp.options['gateway_mtu']))
return
self.fail('Gateway Logical_Router_Port not found for '
'router %s' % router_id)
self.add_fake_chassis('host1', enable_chassis_as_gw=True, azs=[])
net_ext_args = {provider_net.NETWORK_TYPE: 'geneve',
external_net.EXTERNAL: True,
@ -260,11 +260,52 @@ class TestOVNClient(base.TestOVNFunctionalBase,
'add', router_id, snet_int['subnet']['id'],
None)
check_gw_lrp_mtu(router_id, 1300)
self._check_gw_lrp_mtu(router_id, 1300)
# Update external network MTU.
net_ext_args = {'network': {mtu_def.MTU: 1350}}
req = self.new_update_request('networks', net_ext_args,
net_ext['network']['id'])
req.get_response(self.api)
check_gw_lrp_mtu(router_id, 1350)
self._check_gw_lrp_mtu(router_id, 1350)
def test_add_new_router_interfaces_lrp_mtu_updated(self):
mtu_ext = 1350
internal_interfaces = [{'cidr': '10.2.0.0/24', 'mtu': mtu_ext - 10},
{'cidr': '10.3.0.0/24', 'mtu': mtu_ext + 10},
{'cidr': '10.4.0.0/24', 'mtu': mtu_ext - 20}]
self.add_fake_chassis('host1', enable_chassis_as_gw=True, azs=[])
net_ext_args = {provider_net.NETWORK_TYPE: 'geneve',
external_net.EXTERNAL: True,
mtu_def.MTU: mtu_ext}
# Store the network's MTUs connected to the router.
router_attached_net_mtus = {mtu_ext}
with self.network(
'test-ext-net', as_admin=True,
arg_list=tuple(net_ext_args.keys()), **net_ext_args) as \
net_ext:
ext_gw = {'network_id': net_ext['network']['id']}
with self.subnet(net_ext, cidr='10.1.0.0/24'), \
self.router(external_gateway_info=ext_gw) as router:
router_id = router['router']['id']
for _int in internal_interfaces:
# Attach a new internal interface to the router. If the new
# network MTU is lower than the minimum MTU connected, the
# GW LRP.options.gateway_mtu will be updated.
net_int_args = {provider_net.NETWORK_TYPE: 'geneve',
mtu_def.MTU: _int['mtu']}
router_attached_net_mtus.add(_int['mtu'])
net_int = self._make_network(
self.fmt, name='nettest', admin_state_up=True,
**net_int_args)
snet_int = self._make_subnet(
self.fmt, net_int, constants.ATTR_NOT_SPECIFIED,
_int['cidr'])
self._router_interface_action(
'add', router_id, snet_int['subnet']['id'],
None)
# The GW LRP "gateway_mtu" value should be the minimum
# MTU connected to the router.
self._check_gw_lrp_mtu(router_id,
min(router_attached_net_mtus))

7
neutron/tests/unit/plugins/ml2/drivers/ovn/mech_driver/test_mech_driver.py
View File

@ -61,6 +61,7 @@ from neutron.db import ovn_revision_numbers_db
from neutron.db import provisioning_blocks
from neutron.db import securitygroups_db
from neutron.db import segments_db
from neutron.objects import network as network_obj
from neutron.plugins.ml2.drivers.ovn.agent import neutron_agent
from neutron.plugins.ml2.drivers.ovn.mech_driver import mech_driver
from neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb import impl_idl_ovn
@ -2621,6 +2622,12 @@ class TestOVNMechanismDriver(TestOVNMechanismDriverBase):
with self.subnet(network=network) as subnet:
with self.port(subnet=subnet,
device_owner=const.DEVICE_OWNER_ROUTER_GW) as port:
# Manually set the network DB register MTU without calling
# the network update API.
net_obj = network_obj.Network.get_object(
self.context, id=network['network']['id'])
net_obj.mtu = new_mtu
net_obj.update()
grps.return_value = [{'port_id': port['port']['id'],
'network_id':network['network']['id']}]

11
neutron/tests/unit/services/ovn_l3/test_plugin.py
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@ -74,7 +74,8 @@ class BaseTestOVNL3RouterPluginMixin():
revision_plugin.RevisionPlugin()
# MTU needs to be 1442 instead of 1500 because GENEVE headers size
# must be at least 38 when using OVN
network_attrs = {external_net.EXTERNAL: True, 'mtu': 1442}
default_mtu = 1442
network_attrs = {external_net.EXTERNAL: True, 'mtu': default_mtu}
self.fake_network = \
fake_resources.FakeNetwork.create_one_network(
attrs=network_attrs).info()
@ -173,7 +174,10 @@ class BaseTestOVNL3RouterPluginMixin():
ovn_const.OVN_ROUTER_IS_EXT_GW: 'True',
ovn_const.OVN_ROUTER_NAME_EXT_ID_KEY: 'router-id',
},
'options': {}}
'options': {
ovn_const.OVN_ROUTER_PORT_GW_MTU_OPTION: str(default_mtu)
}
}
self.fake_floating_ip_attrs = {'floating_ip_address': '192.168.0.10',
'fixed_ip_address': '10.0.0.10'}
self.fake_floating_ip = fake_resources.FakeFloatingIp.create_one_fip(
@ -2063,7 +2067,7 @@ class TestOVNL3RouterPlugin(BaseTestOVNL3RouterPluginMixin,
self.fake_router_port['device_owner'] = (
constants.DEVICE_OWNER_ROUTER_GW)
gn.return_value = prov_net
gns.return_value = [self.fake_network]
gns.return_value = [self.fake_network, prov_net]
ext_ids = {
ovn_const.OVN_NETTYPE_EXT_ID_KEY: constants.TYPE_GENEVE,
ovn_const.OVN_NETWORK_MTU_EXT_ID_KEY: mtu,
@ -2109,6 +2113,7 @@ class TestOVNL3RouterPluginEmitNeedToFrag(
super().setUp()
config.cfg.CONF.set_override(
'ovn_emit_need_to_frag', False, group='ovn')
self.fake_ext_gw_port_assert['options'] = {}
class OVNL3ExtrarouteTests(test_l3_gw.ExtGwModeIntTestCase,

7
releasenotes/notes/ovn_router_gateway_mtu-ac69e07b30093193.yaml Normal file
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@ -0,0 +1,7 @@
---
features:
- |
Now if the configuration option ``[ovn]ovn_emit_need_to_frag`` is set,
OVN will always set the "gateway_mtu" option in the gateway
``Logical_Router_Port``. The value defined will be the lowest MTU of all
networks connected to this router.