Change duplicate OVS bridge datapath-ids

The native OVS/ofctl controllers talk to the bridges using a
datapath-id, instead of the bridge name. The datapath ID is
auto-generated based on the MAC address of the bridge's NIC.
In the case where bridges are on VLAN interfaces, they would
have the same MACs, therefore the same datapath-id, causing
flows for one physical bridge to be programmed on each other.

The datapath-id is a 64-bit field, with lower 48 bits being
the MAC. We set the upper 12 unused bits to identify each
unique physical bridge

This could also be fixed manually using ovs-vsctl set, but
it might be beneficial to automate this in the code.

ovs-vsctl set bridge <mybr> other-config:datapath-id=<datapathid>

You can change this yourself using above command.

You can view/verify current datapath-id via

ovs-vsctl get Bridge br-vlan datapath-id

(please note that other-config is needed in the set, but not get)

Closes-Bug: #1697243
Co-Authored-By: Rodolfo Alonso Hernandez <>

Change-Id: I575ddf0a66e2cfe745af3874728809cf54e37745
Arjun Baindur 5 years ago committed by Rodolfo Alonso Hernandez
parent 367288e99a
commit 379a9faf62

@ -921,6 +921,11 @@ class OVSBridge(BaseOVS):
'controller_burst_limit', controller_burst_limit)
def set_datapath_id(self, datapath_id):
dpid_cfg = {'datapath-id': datapath_id}
self.set_db_attribute('Bridge', self.br_name, 'other_config', dpid_cfg,
def __enter__(self):
return self

@ -1143,6 +1143,25 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
return sync
def _check_bridge_datapath_id(self, bridge, datapath_ids_set):
"""Check for bridges with duplicate datapath-id
Bottom 48 bits auto-derived from MAC of NIC. Upper 12 bits free,
so we OR it with (bridge # << 48) to create a unique ID
It must be exactly 64 bits, else OVS will reject it - zfill
:param bridge: (OVSPhysicalBridge) bridge
:param datapath_ids_set: (set) used datapath ids in OVS
dpid = int(bridge.get_datapath_id(), 16)
dpid_hex = format(dpid, '0x').zfill(16)
if dpid_hex in datapath_ids_set:
dpid_hex = format(
dpid + (len(datapath_ids_set) << 48), '0x').zfill(16)
bridge.set_datapath_id(dpid_hex)'Bridge %s datapath-id = 0x%s', bridge.br_name, dpid_hex)
def setup_physical_bridges(self, bridge_mappings):
'''Setup the physical network bridges.
@ -1154,6 +1173,7 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
self.phys_brs = {}
self.int_ofports = {}
self.phys_ofports = {}
datapath_ids_set = set()
ip_wrapper = ip_lib.IPWrapper()
ovs = ovs_lib.BaseOVS()
ovs_bridges = ovs.get_bridges()
@ -1171,6 +1191,8 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
'bridge': bridge})
br = self.br_phys_cls(bridge)
self._check_bridge_datapath_id(br, datapath_ids_set)
# The bridge already exists, so create won't recreate it, but will
# handle things like changing the datapath_type

@ -1319,6 +1319,7 @@ class TestOvsNeutronAgent(object):
mock.patch.object(sys, "exit"),\
mock.patch.object(self.agent, 'br_phys_cls') as phys_br_cls,\
mock.patch.object(self.agent, 'int_br') as int_br,\
mock.patch.object(self.agent, '_check_bridge_datapath_id'),\
mock.patch.object(ovs_lib.BaseOVS, 'get_bridges'):
devex_fn.return_value = True
parent = mock.MagicMock()
@ -1398,6 +1399,7 @@ class TestOvsNeutronAgent(object):
mock.patch.object(utils, "execute") as utilsexec_fn,\
mock.patch.object(self.agent, 'br_phys_cls') as phys_br_cls,\
mock.patch.object(self.agent, 'int_br') as int_br,\
mock.patch.object(self.agent, '_check_bridge_datapath_id'),\
mock.patch.object(ip_lib.IPWrapper, "add_veth") as addveth_fn,\
"delete") as linkdel_fn,\
@ -1436,7 +1438,8 @@ class TestOvsNeutronAgent(object):
mock.patch.object(self.agent, 'br_phys_cls') as phys_br_cls,\
mock.patch.object(self.agent, 'int_br') as int_br,\
mock.patch.object(self.agent.int_br, 'db_get_val',
return_value='veth'), \
mock.patch.object(self.agent, '_check_bridge_datapath_id'), \
mock.patch.object(ovs_lib.BaseOVS, 'get_bridges'):
phys_br = phys_br_cls()
parent = mock.MagicMock()
@ -2342,6 +2345,22 @@ class TestOvsNeutronAgent(object):
self.assertRaises(ValueError, self._make_agent)
def test__check_bridge_datapath_id(self):
datapath_id = u'0000622486fa3f42'
datapath_ids_set = set()
for i in range(5):
dpid = format((i << 48) + int(datapath_id, 16), '0x').zfill(16)
bridge = mock.Mock()
bridge.br_name = 'bridge_%s' % i
bridge.get_datapath_id = mock.Mock(return_value=datapath_id)
self.agent._check_bridge_datapath_id(bridge, datapath_ids_set)
self.assertEqual(i + 1, len(datapath_ids_set))
self.assertIn(dpid, datapath_ids_set)
if i == 0:
class TestOvsNeutronAgentOFCtl(TestOvsNeutronAgent,

@ -189,7 +189,9 @@ class TunnelTest(object):
lambda bridge: bridge if bridge in self.ovs_bridges else None)
self.execute = mock.patch('neutron.agent.common.utils.execute').start()
self.mock_check_bridge_datapath_id = mock.patch.object(
def _define_expected_calls(self, arp_responder=False):