diff --git a/xos/synchronizer/__init__.py b/xos/synchronizer/__init__.py
new file mode 100644
index 0000000..8bbb6fa
--- /dev/null
+++ b/xos/synchronizer/__init__.py
@@ -0,0 +1,14 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
\ No newline at end of file
diff --git a/xos/synchronizer/config.yaml b/xos/synchronizer/config.yaml
new file mode 100644
index 0000000..647efdc
--- /dev/null
+++ b/xos/synchronizer/config.yaml
@@ -0,0 +1,42 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+name: tt-workflow-driver
+core_version: ">=2.2.1"
+required_models:
+  - TtWorkflowDriverService
+  - TtWorkflowDriverServiceInstance
+  - RCORDSubscriber
+  - ONUDevice
+model_policies_dir: "/opt/xos/synchronizers/tt-workflow-driver/model_policies"
+models_dir: "/opt/xos/synchronizers/tt-workflow-driver/models"
+event_steps_dir: "/opt/xos/synchronizers/tt-workflow-driver/event_steps"
+logging:
+  version: 1
+  handlers:
+    console:
+      class: logging.StreamHandler
+    file:
+      class: logging.handlers.RotatingFileHandler
+      filename: /var/log/xos.log
+      maxBytes: 10485760
+      backupCount: 5
+  loggers:
+    'multistructlog':
+      handlers:
+          - console
+          - file
+      level: DEBUG
diff --git a/xos/synchronizer/event_steps/dhcp_event.py b/xos/synchronizer/event_steps/dhcp_event.py
new file mode 100644
index 0000000..42f0858
--- /dev/null
+++ b/xos/synchronizer/event_steps/dhcp_event.py
@@ -0,0 +1,46 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+import time
+import os
+import sys
+from xossynchronizer.event_steps.eventstep import EventStep
+from helpers import TtHelpers
+
+class SubscriberDhcpEventStep(EventStep):
+    topics = ["dhcp.events"]
+    technology = "kafka"
+
+    def __init__(self, *args, **kwargs):
+        super(SubscriberDhcpEventStep, self).__init__(*args, **kwargs)
+
+    def process_event(self, event):
+        value = json.loads(event.value)
+
+        onu_sn = TtHelpers.get_onu_sn(self.model_accessor, self.log, value)
+        si = TtHelpers.get_si_by_sn(self.model_accessor, self.log, onu_sn)
+
+        if not si:
+            self.log.exception("dhcp.events: Cannot find tt-workflow-driver service instance for this event", kafka_event=value)
+            raise Exception("dhcp.events: Cannot find tt-workflow-driver service instance for this event")
+
+        self.log.info("dhcp.events: Got event for subscriber", event_value=value, onu_sn=onu_sn, si=si)
+
+        si.dhcp_state = value["messageType"]
+        si.ip_address = value["ipAddress"]
+        si.mac_address = value["macAddress"]
+
+        si.save_changed_fields(always_update_timestamp=True)
diff --git a/xos/synchronizer/event_steps/onu_event.py b/xos/synchronizer/event_steps/onu_event.py
new file mode 100644
index 0000000..386942f
--- /dev/null
+++ b/xos/synchronizer/event_steps/onu_event.py
@@ -0,0 +1,61 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import json
+from xossynchronizer.event_steps.eventstep import EventStep
+
+class ONUEventStep(EventStep):
+    topics = ["onu.events"]
+    technology = "kafka"
+
+    max_onu_retry = 50
+
+    def __init__(self, *args, **kwargs):
+        super(ONUEventStep, self).__init__(*args, **kwargs)
+
+    def get_tt_si(self, event):
+        try:
+            tt_si = self.model_accessor.TtWorkflowDriverServiceInstance.objects.get(serial_number=event["serial_number"])
+            tt_si.no_sync = False;
+            tt_si.uni_port_id = event["uni_port_id"]
+            tt_si.of_dpid = event["of_dpid"]
+            self.log.debug("onu.events: Found existing TtWorkflowDriverServiceInstance", si=tt_si)
+        except IndexError:
+            # create an TtWorkflowDriverServiceInstance, the validation will be triggered in the corresponding sync step
+            tt_si = self.model_accessor.TtWorkflowDriverServiceInstance(
+                serial_number=event["serial_number"],
+                of_dpid=event["of_dpid"],
+                uni_port_id=event["uni_port_id"],
+                owner=self.model_accessor.TtWorkflowDriverService.objects.first() # we assume there is only one TtWorkflowDriverService
+            )
+            self.log.debug("onu.events: Created new TtWorkflowDriverServiceInstance", si=tt_si)
+        return tt_si
+
+    def process_event(self, event):
+        value = json.loads(event.value)
+        self.log.info("onu.events: received event", value=value)
+
+        if value["status"] == "activated":
+            self.log.info("onu.events: activated onu", value=value)
+            tt_si = self.get_tt_si(value)
+            tt_si.onu_state = "ENABLED"
+            tt_si.save_changed_fields(always_update_timestamp=True)
+        elif value["status"] == "disabled":
+            self.log.info("onu.events: disabled onu, not taking any action", value=value)
+            return
+        else:
+            self.log.warn("onu.events: Unknown status value: %s" % value["status"], value=value)
+            return
diff --git a/xos/synchronizer/event_steps/test_dhcp_event.py b/xos/synchronizer/event_steps/test_dhcp_event.py
new file mode 100644
index 0000000..d7934da
--- /dev/null
+++ b/xos/synchronizer/event_steps/test_dhcp_event.py
@@ -0,0 +1,110 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from mock import patch, call, Mock, PropertyMock
+import json
+
+import os, sys
+
+test_path=os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+
+class TestSubscriberAuthEvent(unittest.TestCase):
+
+    def setUp(self):
+
+        self.sys_path_save = sys.path
+
+        # Setting up the config module
+        from xosconfig import Config
+        config = os.path.join(test_path, "../test_config.yaml")
+        Config.clear()
+        Config.init(config, "synchronizer-config-schema.yaml")
+        from multistructlog import create_logger
+        log = create_logger(Config().get('logging'))
+        # END Setting up the config module
+
+        from xossynchronizer.mock_modelaccessor_build import mock_modelaccessor_config
+        mock_modelaccessor_config(test_path, [("tt-workflow-driver", "tt-workflow-driver.xproto"),
+                                              ("olt-service", "volt.xproto"),
+                                              ("rcord", "rcord.xproto")])
+
+        import xossynchronizer.modelaccessor
+        import mock_modelaccessor
+        reload(mock_modelaccessor) # in case nose2 loaded it in a previous test
+        reload(xossynchronizer.modelaccessor)      # in case nose2 loaded it in a previous test
+
+        from xossynchronizer.modelaccessor import model_accessor
+        from dhcp_event import SubscriberDhcpEventStep
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+        self.model_accessor = model_accessor
+        self.log = log
+
+        self.event_step = SubscriberDhcpEventStep(model_accessor=self.model_accessor, log=self.log)
+
+        self.event = Mock()
+
+        self.volt = Mock()
+        self.volt.name = "vOLT"
+        self.volt.leaf_model = Mock()
+
+        # self.subscriber = RCORDSubscriber()
+        # self.subscriber.onu_device = "BRCM1234"
+        # self.subscriber.save = Mock()
+
+        self.mac_address = "00:AA:00:00:00:01"
+        self.ip_address = "192.168.3.5"
+
+        self.si = TtWorkflowDriverServiceInstance()
+        self.si.serial_number = "BRCM1234"
+        self.si.save = Mock()
+
+
+    def tearDown(self):
+        sys.path = self.sys_path_save
+
+    def test_dhcp_subscriber(self):
+
+        self.event.value = json.dumps({
+            "deviceId" : "of:0000000000000001",
+            "portNumber" : "1",
+            "macAddress" : self.mac_address,
+            "ipAddress" : self.ip_address,
+            "messageType": "DHCPREQUEST"
+        })
+
+        with patch.object(VOLTService.objects, "get_items") as volt_service_mock, \
+            patch.object(TtWorkflowDriverServiceInstance.objects, "get_items") as si_mock, \
+            patch.object(self.volt, "get_onu_sn_from_openflow") as get_onu_sn:
+
+            self.assertTrue(VOLTService.objects.first() is not None)
+
+            volt_service_mock.return_value = [self.volt]
+            get_onu_sn.return_value = "BRCM1234"
+            si_mock.return_value = [self.si]
+
+            self.event_step.process_event(self.event)
+
+            self.si.save.assert_called()
+            self.assertEqual(self.si.dhcp_state, "DHCPREQUEST")
+            self.assertEqual(self.si.mac_address, self.mac_address)
+            self.assertEqual(self.si.ip_address, self.ip_address)
+
+if __name__ == '__main__':
+    sys.path.append("..") # for import of helpers.py
+    unittest.main()
\ No newline at end of file
diff --git a/xos/synchronizer/event_steps/test_onu_events.py b/xos/synchronizer/event_steps/test_onu_events.py
new file mode 100644
index 0000000..ea368d5
--- /dev/null
+++ b/xos/synchronizer/event_steps/test_onu_events.py
@@ -0,0 +1,135 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from mock import patch, call, Mock, PropertyMock
+import json
+
+import os, sys
+
+test_path=os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+
+class TestSyncOLTDevice(unittest.TestCase):
+
+    def setUp(self):
+
+        self.sys_path_save = sys.path
+
+        # Setting up the config module
+        from xosconfig import Config
+        config = os.path.join(test_path, "../test_config.yaml")
+        Config.clear()
+        Config.init(config, "synchronizer-config-schema.yaml")
+        # END Setting up the config module
+
+        from xossynchronizer.mock_modelaccessor_build import mock_modelaccessor_config
+        mock_modelaccessor_config(test_path, [("tt-workflow-driver", "tt-workflow-driver.xproto"),
+                                              ("olt-service", "volt.xproto"),
+                                              ("rcord", "rcord.xproto")])
+
+        import xossynchronizer.modelaccessor
+        import mock_modelaccessor
+        reload(mock_modelaccessor) # in case nose2 loaded it in a previous test
+        reload(xossynchronizer.modelaccessor)      # in case nose2 loaded it in a previous test
+
+        from xossynchronizer.modelaccessor import model_accessor
+        from onu_event import ONUEventStep
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+        self.model_accessor = model_accessor
+        self.log = Mock()
+
+        self.event_step = ONUEventStep(model_accessor=self.model_accessor, log=self.log)
+
+        self.event = Mock()
+        self.event_dict = {
+            'status': 'activated',
+            'serial_number': 'BRCM1234',
+            'of_dpid': 'of:109299321',
+            'uni_port_id': 16
+        }
+        self.event.value = json.dumps(self.event_dict)
+
+        self.tt = TtWorkflowDriverService(name="tt-workflow-driver")
+
+    def tearDown(self):
+        sys.path = self.sys_path_save
+
+
+    def test_create_instance(self):
+
+        with patch.object(TtWorkflowDriverServiceInstance.objects, "get_items") as tt_si_mock , \
+            patch.object(TtWorkflowDriverService.objects, "get_items") as service_mock, \
+            patch.object(TtWorkflowDriverServiceInstance, "save", autospec=True) as mock_save:
+
+            tt_si_mock.return_value = []
+            service_mock.return_value = [self.tt]
+
+            self.event_step.process_event(self.event)
+
+            tt_si = mock_save.call_args[0][0]
+
+            self.assertEqual(mock_save.call_count, 1)
+
+            self.assertEqual(tt_si.serial_number, self.event_dict['serial_number'])
+            self.assertEqual(tt_si.of_dpid, self.event_dict['of_dpid'])
+            self.assertEqual(tt_si.uni_port_id, self.event_dict['uni_port_id'])
+            self.assertEqual(tt_si.onu_state, "ENABLED")
+
+    def test_reuse_instance(self):
+
+        si = TtWorkflowDriverServiceInstance(
+            serial_number=self.event_dict["serial_number"],
+            of_dpid="foo",
+            uni_port_id="foo"
+        )
+
+        with patch.object(TtWorkflowDriverServiceInstance.objects, "get_items") as tt_si_mock , \
+            patch.object(TtWorkflowDriverServiceInstance, "save", autospec=True) as mock_save:
+
+            tt_si_mock.return_value = [si]
+
+            self.event_step.process_event(self.event)
+
+            tt_si = mock_save.call_args[0][0]
+
+            self.assertEqual(mock_save.call_count, 1)
+
+            self.assertEqual(tt_si.serial_number, self.event_dict['serial_number'])
+            self.assertEqual(tt_si.of_dpid, self.event_dict['of_dpid'])
+            self.assertEqual(tt_si.uni_port_id, self.event_dict['uni_port_id'])
+            self.assertEqual(tt_si.onu_state, "ENABLED")
+
+    def test_disable_onu(self):
+        self.event_dict = {
+            'status': 'disabled',
+            'serial_number': 'BRCM1234',
+            'of_dpid': 'of:109299321',
+            'uni_port_id': 16
+        }
+        self.event.value = json.dumps(self.event_dict)
+
+        with patch.object(TtWorkflowDriverServiceInstance, "save", autospec=True) as mock_save:
+
+            self.event_step.process_event(self.event)
+
+            self.assertEqual(mock_save.call_count, 0)
+            
+
+if __name__ == '__main__':
+    sys.path.append("..")  # for import of helpers.py
+    unittest.main()
\ No newline at end of file
diff --git a/xos/synchronizer/helpers.py b/xos/synchronizer/helpers.py
new file mode 100644
index 0000000..e67890a
--- /dev/null
+++ b/xos/synchronizer/helpers.py
@@ -0,0 +1,76 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from xossynchronizer.steps.syncstep import DeferredException
+
+class TtHelpers():
+    @staticmethod
+    def validate_onu(model_accessor, log, tt_si):
+        """
+        This method validate an ONU against the whitelist and set the appropriate state.
+        It's expected that the deferred exception is managed in the caller method,
+        for example a model_policy or a sync_step.
+
+        :param tt_si: TtWorkflowDriverServiceInstance
+        :return: [boolean, string]
+        """
+
+        oss_service = tt_si.owner.leaf_model
+
+        # See if there is a matching entry in the whitelist.
+        matching_entries = model_accessor.TtWorkflowDriverWhiteListEntry.objects.filter(
+            owner_id=oss_service.id,
+        )
+        matching_entries = [e for e in matching_entries if e.serial_number.lower() == tt_si.serial_number.lower()]
+
+        if len(matching_entries) == 0:
+            log.warn("ONU not found in whitelist", object=str(tt_si), serial_number=tt_si.serial_number, **tt_si.tologdict())
+            return [False, "ONU not found in whitelist"]
+
+        whitelisted = matching_entries[0]
+        try:
+            pon_port = model_accessor.ONUDevice.objects.get(serial_number=tt_si.serial_number).pon_port
+        except IndexError:
+            raise DeferredException("ONU device %s is not know to XOS yet" % tt_si.serial_number)
+
+        if pon_port.port_no != whitelisted.pon_port_id or tt_si.of_dpid != whitelisted.device_id:
+            log.warn("ONU disable as location don't match",
+                     object=str(tt_si),
+                     serial_number=tt_si.serial_number,
+                     pon_port=pon_port.port_no,
+                     whitelisted_pon_port=whitelisted.pon_port_id,
+                     device_id=tt_si.of_dpid,
+                     whitelisted_device_id=whitelisted.device_id,
+                     **tt_si.tologdict())
+            return [False, "ONU activated in wrong location"]
+
+        return [True, "ONU has been validated"]
+
+    @staticmethod
+    def get_onu_sn(model_accessor, log, event):
+        olt_service = model_accessor.VOLTService.objects.first()
+        onu_sn = olt_service.get_onu_sn_from_openflow(event["deviceId"], event["portNumber"])
+        if not onu_sn or onu_sn is None:
+            log.exception("Cannot find onu serial number for this event", kafka_event=event)
+            raise Exception("Cannot find onu serial number for this event")
+
+        return onu_sn
+
+    @staticmethod
+    def get_si_by_sn(model_accessor, log, serial_number):
+        try:
+            return model_accessor.TtWorkflowDriverServiceInstance.objects.get(serial_number=serial_number)
+        except IndexError:
+            log.exception("Cannot find tt-workflow-driver service instance for this serial number", serial_number=serial_number)
+            raise Exception("Cannot find tt-workflow-driver service instance for this serial number %s", serial_number)
\ No newline at end of file
diff --git a/xos/synchronizer/migrations/0001_initial.py b/xos/synchronizer/migrations/0001_initial.py
new file mode 100644
index 0000000..1b06660
--- /dev/null
+++ b/xos/synchronizer/migrations/0001_initial.py
@@ -0,0 +1,102 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.11 on 2019-03-15 17:42
+from __future__ import unicode_literals
+
+import core.models.xosbase_header
+from django.db import migrations, models
+import django.db.models.deletion
+import django.utils.timezone
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('core', '0002_initial_data'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='TtWorkflowDriverService',
+            fields=[
+                ('service_decl_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='core.Service_decl')),
+            ],
+            options={
+                'verbose_name': 'TtWorkflowDriver Service',
+            },
+            bases=('core.service',),
+        ),
+        migrations.CreateModel(
+            name='TtWorkflowDriverServiceInstance',
+            fields=[
+                ('serviceinstance_decl_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='core.ServiceInstance_decl')),
+                ('serial_number', models.CharField(help_text=b'Serial number of ONU', max_length=254, unique=True)),
+                ('of_dpid', models.CharField(help_text=b'OLT Openflow ID', max_length=254)),
+                ('uni_port_id', models.IntegerField(help_text=b'ONU UNI port ID')),
+                ('onu_state', models.CharField(choices=[(b'AWAITING', b'Awaiting'), (b'ENABLED', b'Enabled'), (b'DISABLED', b'Disabled')], default=b'AWAITING', help_text=b'ONU administrative state', max_length=254)),
+                ('status_message', models.CharField(blank=True, default=b'', help_text=b'Status text of current state machine state', max_length=254, null=True)),
+                ('dhcp_state', models.CharField(choices=[(b'AWAITING', b'Awaiting'), (b'DHCPDISCOVER', b'DHCPDISCOVER'), (b'DHCPACK', b'DHCPACK'), (b'DHCPREQUEST', b'DHCPREQUEST')], default=b'AWAITING', max_length=254)),
+                ('ip_address', models.CharField(blank=True, help_text=b'Management IP address, learned from DHCP', max_length=20, null=True)),
+                ('mac_address', models.CharField(blank=True, help_text=b'Management MAC address, leanred from DHCP', max_length=20, null=True)),
+            ],
+            options={
+                'verbose_name': 'TtWorkflowDriver Service Instance',
+            },
+            bases=('core.serviceinstance',),
+        ),
+        migrations.CreateModel(
+            name='TtWorkflowDriverWhiteListEntry',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('created', models.DateTimeField(auto_now_add=True, help_text=b'Time this model was created')),
+                ('updated', models.DateTimeField(default=django.utils.timezone.now, help_text=b'Time this model was changed by a non-synchronizer')),
+                ('enacted', models.DateTimeField(blank=True, default=None, help_text=b'When synced, set to the timestamp of the data that was synced', null=True)),
+                ('policed', models.DateTimeField(blank=True, default=None, help_text=b'When policed, set to the timestamp of the data that was policed', null=True)),
+                ('backend_register', models.CharField(blank=True, default=b'{}', max_length=1024, null=True)),
+                ('backend_need_delete', models.BooleanField(default=False)),
+                ('backend_need_reap', models.BooleanField(default=False)),
+                ('backend_status', models.CharField(default=b'Provisioning in progress', max_length=1024)),
+                ('backend_code', models.IntegerField(default=0)),
+                ('deleted', models.BooleanField(default=False)),
+                ('write_protect', models.BooleanField(default=False)),
+                ('lazy_blocked', models.BooleanField(default=False)),
+                ('no_sync', models.BooleanField(default=False)),
+                ('no_policy', models.BooleanField(default=False)),
+                ('policy_status', models.CharField(blank=True, default=b'Policy in process', max_length=1024, null=True)),
+                ('policy_code', models.IntegerField(blank=True, default=0, null=True)),
+                ('leaf_model_name', models.CharField(help_text=b'The most specialized model in this chain of inheritance, often defined by a service developer', max_length=1024)),
+                ('backend_need_delete_policy', models.BooleanField(default=False, help_text=b'True if delete model_policy must be run before object can be reaped')),
+                ('xos_managed', models.BooleanField(default=True, help_text=b'True if xos is responsible for creating/deleting this object')),
+                ('backend_handle', models.CharField(blank=True, help_text=b'Handle used by the backend to track this object', max_length=1024, null=True)),
+                ('changed_by_step', models.DateTimeField(blank=True, default=None, help_text=b'Time this model was changed by a sync step', null=True)),
+                ('changed_by_policy', models.DateTimeField(blank=True, default=None, help_text=b'Time this model was changed by a model policy', null=True)),
+                ('serial_number', models.CharField(help_text=b'ONU Serial Number', max_length=254)),
+                ('pon_port_id', models.IntegerField(help_text=b'PON Port on which this ONU is expected to show up')),
+                ('device_id', models.CharField(help_text=b'OLT Device (logical device id) on which this ONU is expected to show up', max_length=54)),
+                ('owner', models.ForeignKey(help_text=b'TtWorkflowDriverService that owns this white list entry', on_delete=django.db.models.deletion.CASCADE, related_name='whitelist_entries', to='tt-workflow-driver.TtWorkflowDriverService')),
+            ],
+            options={
+                'verbose_name': 'ONU Whitelist',
+            },
+            bases=(models.Model, core.models.xosbase_header.PlModelMixIn),
+        ),
+        migrations.AlterUniqueTogether(
+            name='ttworkflowdriverwhitelistentry',
+            unique_together=set([('owner', 'serial_number')]),
+        ),
+    ]
diff --git a/xos/synchronizer/migrations/__init__.py b/xos/synchronizer/migrations/__init__.py
new file mode 100644
index 0000000..eb28b96
--- /dev/null
+++ b/xos/synchronizer/migrations/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
\ No newline at end of file
diff --git a/xos/synchronizer/model_policies/model_policy_tt_workflow_driver_serviceinstance.py b/xos/synchronizer/model_policies/model_policy_tt_workflow_driver_serviceinstance.py
new file mode 100644
index 0000000..95081c8
--- /dev/null
+++ b/xos/synchronizer/model_policies/model_policy_tt_workflow_driver_serviceinstance.py
@@ -0,0 +1,170 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+
+from xossynchronizer.model_policies.policy import Policy
+
+import os
+import sys
+
+sync_path = os.path.abspath(os.path.join(os.path.dirname(os.path.realpath(__file__)), ".."))
+sys.path.append(sync_path)
+
+from helpers import TtHelpers
+
+class DeferredException(Exception):
+    pass
+
+class TtWorkflowDriverServiceInstancePolicy(Policy):
+    model_name = "TtWorkflowDriverServiceInstance"
+
+    def handle_create(self, si):
+        self.logger.debug("MODEL_POLICY: handle_create for TtWorkflowDriverServiceInstance %s " % si.id)
+        self.handle_update(si)
+
+    def handle_update(self, si):
+        self.logger.debug("MODEL_POLICY: handle_update for TtWorkflowDriverServiceInstance %s " % (si.id), onu_state=si.onu_state)
+
+        self.process_onu_state(si)
+        self.process_dhcp_state(si)
+
+        self.validate_states(si)
+
+        # handling the subscriber status
+        # It's a combination of all the other states
+        subscriber = self.get_subscriber(si.serial_number)
+        if subscriber:
+            self.update_subscriber(subscriber, si)
+
+        si.save_changed_fields()
+
+    def process_onu_state(self, si):
+        [valid, message] = TtHelpers.validate_onu(self.model_accessor, self.logger, si)
+        if si.onu_state == "AWAITING" or si.onu_state == "ENABLED":
+            si.status_message = message
+            if valid:
+                si.onu_state = "ENABLED"
+                self.update_onu(si.serial_number, "ENABLED")
+            else:
+                si.onu_state = "DISABLED"
+                self.update_onu(si.serial_number, "DISABLED")
+        else: # DISABLED
+            if not valid:
+                si.status_message = message
+            else:
+                si.status_message = "ONU has been disabled"
+            self.update_onu(si.serial_number, "DISABLED")
+
+
+    # The DhcpL2Relay ONOS app generates events that update the fields below.
+    # It only sends events when it processes DHCP packets.  It keeps no internal state.
+    def process_dhcp_state(self, si):
+        if si.onu_state in ["AWAITING", "DISABLED"]:
+            si.ip_address = ""
+            si.mac_address = ""
+            si.dhcp_state = "AWAITING"
+
+    # Make sure the object is in a legitimate state
+    # It should be after the above processing steps
+    # However this might still fail if an event has fired in the meantime
+    # Valid states:
+    # ONU       | DHCP
+    # ===============================
+    # AWAITING  | AWAITING
+    # ENABLED   | *
+    # DISABLED  | AWAITING
+    def validate_states(self, si):
+        if (si.onu_state == "AWAITING" or si.onu_state == "DISABLED") and si.dhcp_state == "AWAITING":
+            return
+        if si.onu_state == "ENABLED":
+            return
+        self.logger.warning("MODEL_POLICY (validate_states): invalid state combination", onu_state=si.onu_state, dhcp_state=si.dhcp_state)
+
+
+    def update_onu(self, serial_number, admin_state):
+        onu = [onu for onu in self.model_accessor.ONUDevice.objects.all() if onu.serial_number.lower() == serial_number.lower()][0]
+        if onu.admin_state == admin_state:
+            self.logger.debug("MODEL_POLICY: ONUDevice [%s] already has admin_state to %s" % (serial_number, admin_state))
+        else:
+            self.logger.debug("MODEL_POLICY: setting ONUDevice [%s] admin_state to %s" % (serial_number, admin_state))
+            onu.admin_state = admin_state
+            onu.save_changed_fields(always_update_timestamp=True)
+
+    def get_subscriber(self, serial_number):
+        try:
+            return [s for s in self.model_accessor.RCORDSubscriber.objects.all() if s.onu_device.lower() == serial_number.lower()][0]
+        except IndexError:
+            # If the subscriber doesn't exist we don't do anything
+            self.logger.debug("MODEL_POLICY: subscriber does not exists for this SI, doing nothing", onu_device=serial_number)
+            return None
+
+    def update_subscriber_ip(self, subscriber, ip):
+        # TODO check if the subscriber has an IP and update it,
+        # or create a new one
+        try:
+            ip = self.model_accessor.RCORDIpAddress.objects.filter(
+                subscriber_id=subscriber.id,
+                ip=ip
+            )[0]
+            self.logger.debug("MODEL_POLICY: found existing RCORDIpAddress for subscriber", onu_device=subscriber.onu_device, subscriber_status=subscriber.status, ip=ip)
+            ip.save_changed_fields()
+        except IndexError:
+            self.logger.debug("MODEL_POLICY: Creating new RCORDIpAddress for subscriber", onu_device=subscriber.onu_device, subscriber_status=subscriber.status, ip=ip)
+            ip = self.model_accessor.RCORDIpAddress(
+                subscriber_id=subscriber.id,
+                ip=ip,
+                description="DHCP Assigned IP Address"
+            )
+            ip.save()
+
+    def delete_subscriber_ip(self, subscriber, ip):
+        try:
+            ip = self.model_accessor.RCORDIpAddress.objects.filter(
+                subscriber_id=subscriber.id,
+                ip=ip
+            )[0]
+            self.logger.debug("MODEL_POLICY: delete RCORDIpAddress for subscriber", onu_device=subscriber.onu_device, subscriber_status=subscriber.status, ip=ip)
+            ip.delete()
+        except:
+            self.logger.warning("MODEL_POLICY: no RCORDIpAddress object found, cannot delete", ip=ip)
+
+    def update_subscriber(self, subscriber, si):
+        cur_status = subscriber.status
+        # Don't change state if someone has disabled the subscriber
+        if subscriber.status != "disabled":
+            if si.onu_state == "ENABLED":
+                subscriber.status = "enabled"
+            elif si.onu_state == "DISABLED":
+                subscriber.status = "awaiting-auth"
+
+        # NOTE we save the subscriber only if:
+        # - the status has changed
+        # - we get a DHCPACK event
+        if cur_status != subscriber.status or si.dhcp_state == "DHCPACK":
+            self.logger.debug("MODEL_POLICY: updating subscriber", onu_device=subscriber.onu_device, subscriber_status=subscriber.status)
+            if subscriber.status == "awaiting-auth":
+                self.delete_subscriber_ip(subscriber, si.ip_address)
+                subscriber.mac_address = ""
+            elif si.ip_address and si.mac_address:
+                self.update_subscriber_ip(subscriber, si.ip_address)
+                subscriber.mac_address = si.mac_address
+            subscriber.save_changed_fields(always_update_timestamp=True)
+        else:
+            self.logger.debug("MODEL_POLICY: subscriber status has not changed", onu_device=subscriber.onu_device,
+                              subscriber_status=subscriber.status)
+
+    def handle_delete(self, si):
+        pass
diff --git a/xos/synchronizer/model_policies/model_policy_tt_workflow_driver_whitelistentry.py b/xos/synchronizer/model_policies/model_policy_tt_workflow_driver_whitelistentry.py
new file mode 100644
index 0000000..b16642a
--- /dev/null
+++ b/xos/synchronizer/model_policies/model_policy_tt_workflow_driver_whitelistentry.py
@@ -0,0 +1,75 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from xossynchronizer.model_policies.policy import Policy
+import os
+import sys
+
+sync_path = os.path.abspath(os.path.join(os.path.dirname(os.path.realpath(__file__)), ".."))
+sys.path.append(sync_path)
+
+from helpers import TtHelpers
+
+class TtWorkflowDriverWhiteListEntryPolicy(Policy):
+    model_name = "TtWorkflowDriverWhiteListEntry"
+
+    def handle_create(self, whitelist):
+        self.handle_update(whitelist)
+
+    # Update the SI if the onu_state has changed.
+    # The SI model policy will take care of updating other state.
+    def validate_onu_state(self, si):
+        [valid, message] = TtHelpers.validate_onu(self.model_accessor, self.logger, si)
+        if valid:
+            si.onu_state = "ENABLED"
+        else:
+            si.onu_state = "DISABLED"
+
+        self.logger.debug(
+            "MODEL_POLICY: activating TtWorkflowDriverServiceInstance because of change in the whitelist", si=si, onu_state=si.onu_state)
+        si.save_changed_fields(always_update_timestamp=True)
+
+    def handle_update(self, whitelist):
+        self.logger.debug("MODEL_POLICY: handle_update for TtWorkflowDriverWhiteListEntry", whitelist=whitelist)
+
+        sis = self.model_accessor.TtWorkflowDriverServiceInstance.objects.all()
+
+        for si in sis:
+
+            if si.serial_number.lower() != whitelist.serial_number.lower():
+                # NOTE we don't care about this SI as it has a different serial number
+                continue
+
+            self.validate_onu_state(si)
+
+        whitelist.backend_need_delete_policy=True
+        whitelist.save_changed_fields()
+
+    def handle_delete(self, whitelist):
+        self.logger.debug("MODEL_POLICY: handle_delete for TtWorkflowDriverWhiteListEntry", serial_number=whitelist.serial_number, pon_port=whitelist.pon_port_id, device=whitelist.device_id)
+
+        # BUG: Sometimes the delete policy is not called, because the reaper deletes
+
+        assert(whitelist.owner)
+
+        sis = self.model_accessor.TtWorkflowDriverServiceInstance.objects.all()
+        sis = [si for si in sis if si.serial_number.lower() == whitelist.serial_number.lower()]
+
+        for si in sis:
+            self.validate_onu_state(si)
+
+        whitelist.backend_need_reap=True
+        whitelist.save_changed_fields()
diff --git a/xos/synchronizer/model_policies/test_model_policy_tt_workflow_driver_serviceinstance.py b/xos/synchronizer/model_policies/test_model_policy_tt_workflow_driver_serviceinstance.py
new file mode 100644
index 0000000..a067779
--- /dev/null
+++ b/xos/synchronizer/model_policies/test_model_policy_tt_workflow_driver_serviceinstance.py
@@ -0,0 +1,270 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import unittest
+from mock import patch, call, Mock, PropertyMock
+
+import os, sys
+
+test_path=os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+
+
+class TestModelPolicyTtWorkflowDriverServiceInstance(unittest.TestCase):
+    def setUp(self):
+
+        self.sys_path_save = sys.path
+
+        config = os.path.join(test_path, "../test_config.yaml")
+        from xosconfig import Config
+        Config.clear()
+        Config.init(config, 'synchronizer-config-schema.yaml')
+
+        from xossynchronizer.mock_modelaccessor_build import mock_modelaccessor_config
+        mock_modelaccessor_config(test_path, [("tt-workflow-driver", "tt-workflow-driver.xproto"),
+                                              ("olt-service", "volt.xproto"),
+                                              ("rcord", "rcord.xproto")])
+
+        import xossynchronizer.modelaccessor
+        import mock_modelaccessor
+        reload(mock_modelaccessor) # in case nose2 loaded it in a previous test
+        reload(xossynchronizer.modelaccessor)      # in case nose2 loaded it in a previous test
+
+        from xossynchronizer.modelaccessor import model_accessor
+        from model_policy_tt_workflow_driver_serviceinstance import TtWorkflowDriverServiceInstancePolicy, TtHelpers
+        self.TtHelpers = TtHelpers
+
+        from mock_modelaccessor import MockObjectList
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+        # Some of the functions we call have side-effects. For example, creating a VSGServiceInstance may lead to creation of
+        # tags. Ideally, this wouldn't happen, but it does. So make sure we reset the world.
+        model_accessor.reset_all_object_stores()
+
+
+        self.policy = TtWorkflowDriverServiceInstancePolicy(model_accessor=model_accessor)
+        self.si = TtWorkflowDriverServiceInstance()
+        self.si.owner = TtWorkflowDriverService()
+        self.si.serial_number = "BRCM1234"
+
+    def tearDown(self):
+        sys.path = self.sys_path_save
+
+    def test_update_onu(self):
+
+        onu = ONUDevice(
+            serial_number="BRCM1234",
+            admin_state="ENABLED"
+        )
+        with patch.object(ONUDevice.objects, "get_items") as get_onu, \
+            patch.object(onu, "save") as onu_save:
+            get_onu.return_value = [onu]
+
+            self.policy.update_onu("brcm1234", "ENABLED")
+            onu_save.assert_not_called()
+
+            self.policy.update_onu("brcm1234", "DISABLED")
+            self.assertEqual(onu.admin_state, "DISABLED")
+            onu_save.assert_called_with(always_update_timestamp=True, update_fields=['admin_state', 'serial_number', 'updated'])
+
+
+    def test_enable_onu(self):
+        with patch.object(self.TtHelpers, "validate_onu") as validate_onu, \
+            patch.object(self.policy, "update_onu") as update_onu, \
+            patch.object(self.si, "save") as save_si:
+            validate_onu.return_value = [True, "valid onu"]
+
+            self.policy.process_onu_state(self.si)
+
+            update_onu.assert_called_once()
+            update_onu.assert_called_with("BRCM1234", "ENABLED")
+
+            self.assertIn("valid onu", self.si.status_message)
+
+    def test_disable_onu(self):
+        with patch.object(self.TtHelpers, "validate_onu") as validate_onu, \
+                patch.object(self.policy, "update_onu") as update_onu, \
+                patch.object(self.si, "save") as save_si:
+            validate_onu.return_value = [False, "invalid onu"]
+
+            self.policy.process_onu_state(self.si)
+
+            update_onu.assert_called_once()
+            update_onu.assert_called_with("BRCM1234", "DISABLED")
+
+            self.assertIn("invalid onu", self.si.status_message)
+
+    def test_handle_update_validate_onu(self):
+        """
+        Testing that handle_update calls validate_onu with the correct parameters
+        when necessary
+        """
+        with patch.object(self.policy, "process_onu_state") as process_onu_state, \
+            patch.object(self.policy, "update_onu") as update_onu, \
+            patch.object(self.policy, "get_subscriber") as get_subscriber:
+            update_onu.return_value = None
+            get_subscriber.return_value = None
+
+            self.si.onu_state = "AWAITING"
+            self.policy.handle_update(self.si)
+            process_onu_state.assert_called_with(self.si)
+
+            self.si.onu_state = "ENABLED"
+            self.policy.handle_update(self.si)
+            process_onu_state.assert_called_with(self.si)
+
+            self.si.onu_state = "DISABLED"
+            self.policy.handle_update(self.si)
+            process_onu_state.assert_called_with(self.si)
+
+
+    def test_get_subscriber(self):
+
+        sub = RCORDSubscriber(
+            onu_device="BRCM1234"
+        )
+
+        with patch.object(RCORDSubscriber.objects, "get_items") as get_subscribers:
+            get_subscribers.return_value = [sub]
+
+            res = self.policy.get_subscriber("BRCM1234")
+            self.assertEqual(res, sub)
+
+            res = self.policy.get_subscriber("brcm1234")
+            self.assertEqual(res, sub)
+
+            res = self.policy.get_subscriber("foo")
+            self.assertEqual(res, None)
+
+    def test_update_subscriber(self):
+
+        sub = RCORDSubscriber(
+            onu_device="BRCM1234"
+        )
+
+        self.si.status_message = "some content"
+
+        with patch.object(sub, "save") as sub_save:
+            self.si.onu_state = "ENABLED"
+            sub.status = "awaiting-auth"
+            self.policy.update_subscriber(sub, self.si)
+            self.assertEqual(sub.status, "enabled")
+            sub_save.assert_called()
+            sub_save.reset_mock()
+            sub.status = None
+
+            self.si.onu_state = "DISABLED"
+            sub.status = "enabled"
+            self.policy.update_subscriber(sub, self.si)
+            self.assertEqual(sub.status, "awaiting-auth")
+            sub_save.assert_called()
+            sub_save.reset_mock()
+            sub.status = None
+
+    def test_update_subscriber_not(self):
+        sub = RCORDSubscriber(
+            onu_device="BRCM1234"
+        )
+
+        with patch.object(sub, "save") as sub_save:
+            sub.status = "enabled"
+            self.si.onu_state = "ENABLED"
+            self.policy.update_subscriber(sub, self.si)
+            sub_save.assert_not_called()
+
+            sub.status = "awaiting-auth"
+            self.si.onu_state = "DISABLED"
+            self.policy.update_subscriber(sub, self.si)
+            sub_save.assert_not_called()
+
+    def test_update_subscriber_dhcp_with_exiting_ip(self):
+        sub = RCORDSubscriber(
+            id=10,
+            onu_device="BRCM1234"
+        )
+
+        ip = RCORDIpAddress(
+            subscriber_id=sub.id,
+            ip='10.11.2.23'
+        )
+
+        self.si.dhcp_state = "DHCPACK"
+        self.si.ip_address = "10.11.2.23"
+        self.si.mac_address = "4321"
+
+        with patch.object(sub, "save") as sub_save, \
+            patch.object(RCORDIpAddress.objects, "get_items") as get_ips, \
+            patch.object(ip, "save_changed_fields") as ip_mock:
+
+            get_ips.return_value = [ip]
+            ip_mock.return_value = []
+
+            self.policy.update_subscriber(sub, self.si)
+            sub_save.assert_called()
+            self.assertEqual(sub.mac_address, self.si.mac_address)
+
+            ip_mock.assert_called_with()
+
+    def test_update_subscriber_dhcp_with_new_ip(self):
+        sub = RCORDSubscriber(
+            id=10,
+            onu_device="BRCM1234"
+        )
+
+        self.si.dhcp_state = "DHCPACK"
+        self.si.ip_address = "10.11.2.23"
+        self.si.mac_address = "4321"
+
+        with patch.object(sub, "save") as sub_save, \
+            patch.object(RCORDIpAddress, "save", autospec=True) as ip_mock:
+
+            ip_mock.return_value = []
+
+            self.policy.update_subscriber(sub, self.si)
+            sub_save.assert_called()
+            self.assertEqual(sub.mac_address, self.si.mac_address)
+
+            saved_ip = ip_mock.call_args[0][0]
+            self.assertEqual(saved_ip.ip, self.si.ip_address)
+            self.assertEqual(saved_ip.subscriber_id, sub.id)
+            self.assertEqual(saved_ip.description, "DHCP Assigned IP Address")
+
+    def test_handle_update_subscriber(self):
+        self.si.onu_state = "DISABLED"
+
+        sub = RCORDSubscriber(
+            onu_device="BRCM1234"
+        )
+
+        with patch.object(self.policy, "get_subscriber") as get_subscriber, \
+            patch.object(self.policy, "update_onu") as update_onu, \
+            patch.object(self.policy, "update_subscriber") as update_subscriber:
+
+            get_subscriber.return_value = None
+            self.policy.handle_update(self.si)
+            update_onu.assert_called_with(sub.onu_device, "DISABLED");
+            self.assertEqual(update_subscriber.call_count, 0)
+
+            get_subscriber.return_value = sub
+            self.policy.handle_update(self.si)
+            update_subscriber.assert_called_with(sub, self.si)
+
+
+if __name__ == '__main__':
+    unittest.main()
+
diff --git a/xos/synchronizer/model_policies/test_model_policy_tt_workflow_driver_whitelistentry.py b/xos/synchronizer/model_policies/test_model_policy_tt_workflow_driver_whitelistentry.py
new file mode 100644
index 0000000..bee8971
--- /dev/null
+++ b/xos/synchronizer/model_policies/test_model_policy_tt_workflow_driver_whitelistentry.py
@@ -0,0 +1,119 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import unittest
+from mock import patch, call, Mock, PropertyMock
+
+import os, sys
+
+test_path=os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+
+class TestModelPolicyTtWorkflowDriverWhiteListEntry(unittest.TestCase):
+    def setUp(self):
+        self.sys_path_save = sys.path
+
+        config = os.path.join(test_path, "../test_config.yaml")
+        from xosconfig import Config
+        Config.clear()
+        Config.init(config, 'synchronizer-config-schema.yaml')
+
+        from xossynchronizer.mock_modelaccessor_build import mock_modelaccessor_config
+        mock_modelaccessor_config(test_path, [("tt-workflow-driver", "tt-workflow-driver.xproto"),
+                                              ("olt-service", "volt.xproto"),
+                                              ("rcord", "rcord.xproto")])
+
+        import xossynchronizer.modelaccessor
+        import mock_modelaccessor
+        reload(mock_modelaccessor) # in case nose2 loaded it in a previous test
+        reload(xossynchronizer.modelaccessor)      # in case nose2 loaded it in a previous test
+
+        from xossynchronizer.modelaccessor import model_accessor
+        from model_policy_tt_workflow_driver_whitelistentry import TtWorkflowDriverWhiteListEntryPolicy, TtHelpers
+        self.TtHelpers = TtHelpers
+
+        from mock_modelaccessor import MockObjectList
+        self.MockObjectList = MockObjectList
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+        # Some of the functions we call have side-effects. For example, creating a VSGServiceInstance may lead to creation of
+        # tags. Ideally, this wouldn't happen, but it does. So make sure we reset the world.
+        model_accessor.reset_all_object_stores()
+
+        self.policy = TtWorkflowDriverWhiteListEntryPolicy(model_accessor=model_accessor)
+
+        self.service = TtWorkflowDriverService()
+
+
+    def tearDown(self):
+        sys.path = self.sys_path_save
+        self.service = None
+
+    def test_enable_onu(self):
+        si = TtWorkflowDriverServiceInstance(serial_number="BRCM333", owner_id=self.service.id, valid="invalid")
+        with patch.object(self.TtHelpers, "validate_onu") as validate_onu, \
+            patch.object(si, "save") as save_si:
+            validate_onu.return_value = [True, "valid onu"]
+
+            self.policy.validate_onu_state(si)
+
+            save_si.assert_called_once()
+            save_si.assert_called_with(always_update_timestamp=True, update_fields=['onu_state', 'serial_number', 'updated'])
+
+    def test_disable_onu(self):
+        si = TtWorkflowDriverServiceInstance(serial_number="BRCM333", owner_id=self.service.id, valid="invalid")
+        with patch.object(self.TtHelpers, "validate_onu") as validate_onu, \
+            patch.object(si, "save") as save_si:
+            validate_onu.return_value = [False, "invalid onu"]
+
+            self.policy.validate_onu_state(si)
+
+            save_si.assert_called_once()
+            save_si.assert_called_with(always_update_timestamp=True, update_fields=['onu_state', 'serial_number', 'updated'])
+
+    def test_whitelist_update(self):
+        si = TtWorkflowDriverServiceInstance(serial_number="BRCM333", owner_id=self.service.id)
+        wle = TtWorkflowDriverWhiteListEntry(serial_number="brcm333", owner_id=self.service.id, owner=self.service)
+        with patch.object(TtWorkflowDriverServiceInstance.objects, "get_items") as oss_si_items, \
+            patch.object(self.policy, "validate_onu_state") as validate_onu_state, \
+            patch.object(wle, "save") as wle_save:
+            oss_si_items.return_value = [si]
+
+
+            self.policy.handle_update(wle)
+
+            validate_onu_state.assert_called_with(si)
+            self.assertTrue(wle.backend_need_delete_policy)
+            wle_save.assert_called_with(always_update_timestamp=False, update_fields=['backend_need_delete_policy', 'owner', 'serial_number'])
+
+    def test_whitelist_delete(self):
+        si = TtWorkflowDriverServiceInstance(serial_number="BRCM333", owner_id=self.service.id)
+        wle = TtWorkflowDriverWhiteListEntry(serial_number="brcm333", owner_id=self.service.id, owner=self.service)
+        with patch.object(TtWorkflowDriverServiceInstance.objects, "get_items") as oss_si_items, \
+                patch.object(self.policy, "validate_onu_state") as validate_onu_state, \
+                patch.object(wle, "save") as wle_save:
+            oss_si_items.return_value = [si]
+
+            self.policy.handle_delete(wle)
+
+            validate_onu_state.assert_called_with(si)
+            self.assertTrue(wle.backend_need_reap)
+            wle_save.assert_called_with(always_update_timestamp=False, update_fields=['backend_need_reap', 'owner', 'serial_number'])
+if __name__ == '__main__':
+    unittest.main()
+
diff --git a/xos/synchronizer/models/tt-workflow-driver.xproto b/xos/synchronizer/models/tt-workflow-driver.xproto
new file mode 100644
index 0000000..2b6c889
--- /dev/null
+++ b/xos/synchronizer/models/tt-workflow-driver.xproto
@@ -0,0 +1,69 @@
+option name = "tt-workflow-driver";
+option app_label = "tt-workflow-driver";
+
+message TtWorkflowDriverService (Service){
+    option verbose_name = "TtWorkflowDriver Service";
+    option kind = "control";
+    option description = "Service that manages the Turk Telekom Subscriber workflow";
+}
+
+message TtWorkflowDriverServiceInstance (ServiceInstance){
+    option owner_class_name = "TtWorkflowDriverService";
+    option verbose_name = "TtWorkflowDriver Service Instance";
+    option description = "Workflow settings for a particular ONU Device";
+
+    required string serial_number = 2 [
+        help_text = "Serial number of ONU",
+        max_length = 254,
+        tosca_key=True,
+        unique = True];
+    required string of_dpid = 4 [
+        help_text = "OLT Openflow ID",
+        max_length = 254];
+    required int32 uni_port_id = 5 [
+        help_text = "ONU UNI port ID"];
+    required string onu_state = 6 [
+        help_text = "ONU administrative state",
+        choices = "(('AWAITING', 'Awaiting'), ('ENABLED', 'Enabled'), ('DISABLED', 'Disabled'))",
+        default = "AWAITING",
+        feedback_state = True,
+        max_length = 254];
+    optional string status_message = 7 [
+        help_text = "Status text of current state machine state",
+        default = "",
+        max_length = 254];
+    required string dhcp_state = 8 [
+        max_length = 254,
+        default = "AWAITING",
+        choices = "(('AWAITING', 'Awaiting'), ('DHCPDISCOVER', 'DHCPDISCOVER'), ('DHCPACK', 'DHCPACK'), ('DHCPREQUEST', 'DHCPREQUEST'))",
+        feedback_state = True];
+    optional string ip_address = 9 [
+        help_text = "Management IP address, learned from DHCP",
+        feedback_state = True,
+        max_length = 20];
+    optional string mac_address = 10 [
+        help_text = "Management MAC address, leanred from DHCP",
+        feedback_state = True,
+        max_length = 20];
+}
+
+message TtWorkflowDriverWhiteListEntry (XOSBase) {
+    option verbose_name = "ONU Whitelist";
+    option plural = "ttworkflowdriverwhitelistentries";
+    option description = "White list entry that permits an ONU with a particular serial number on a particular OLT and PON";
+
+    required manytoone owner->TtWorkflowDriverService:whitelist_entries = 1:1001 [
+        help_text = "TtWorkflowDriverService that owns this white list entry",
+        db_index = True,
+        tosca_key = True];
+    required string serial_number = 2 [
+        help_text = "ONU Serial Number",
+        max_length = 254,
+        tosca_key = True,
+        unique_with = "owner"];
+    required int32 pon_port_id = 3 [
+        help_text = "PON Port on which this ONU is expected to show up"];
+    required string device_id = 4 [
+        help_text = "OLT Device (logical device id) on which this ONU is expected to show up",
+        max_length = 54];
+}
diff --git a/xos/synchronizer/test_config.yaml b/xos/synchronizer/test_config.yaml
new file mode 100644
index 0000000..3f33a21
--- /dev/null
+++ b/xos/synchronizer/test_config.yaml
@@ -0,0 +1,31 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+name: test-TtWorkflowDriverService-config
+accessor:
+  username: xosadmin@opencord.org
+  password: "sample"
+  kind: "testframework"
+logging:
+  version: 1
+  handlers:
+    console:
+      class: logging.StreamHandler
+  loggers:
+    'multistructlog':
+      handlers:
+          - console
+#      level: DEBUG
diff --git a/xos/synchronizer/test_helpers.py b/xos/synchronizer/test_helpers.py
new file mode 100644
index 0000000..e46cbc9
--- /dev/null
+++ b/xos/synchronizer/test_helpers.py
@@ -0,0 +1,163 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from mock import patch, call, Mock, PropertyMock
+import json
+
+import os, sys
+
+test_path=os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+
+
+class TestTtHelpers(unittest.TestCase):
+
+    def setUp(self):
+
+        self.sys_path_save = sys.path
+
+        # Setting up the config module
+        from xosconfig import Config
+        config = os.path.join(test_path, "test_config.yaml")
+        Config.clear()
+        Config.init(config, "synchronizer-config-schema.yaml")
+        # END Setting up the config module
+
+        from multistructlog import create_logger
+        self.log = create_logger(Config().get('logging'))
+
+        from xossynchronizer.mock_modelaccessor_build import mock_modelaccessor_config
+        mock_modelaccessor_config(test_path, [("tt-workflow-driver", "tt-workflow-driver.xproto"),
+                                              ("olt-service", "volt.xproto"),
+                                              ("rcord", "rcord.xproto")])
+
+        import xossynchronizer.modelaccessor
+        import mock_modelaccessor
+        reload(mock_modelaccessor) # in case nose2 loaded it in a previous test
+        reload(xossynchronizer.modelaccessor)      # in case nose2 loaded it in a previous test
+
+        from xossynchronizer.modelaccessor import model_accessor
+        from helpers import TtHelpers
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+        self.helpers = TtHelpers
+        self.model_accessor = model_accessor
+
+        self._volt = VOLTService()
+        self._volt.id = 1
+
+        self.volt = Service()
+        self.volt.id = 1
+        self.volt.name = "vOLT"
+        self.volt.leaf_model = self._volt
+
+        self.pon_port = PONPort()
+        self.pon_port.port_no = 1234
+
+        self.onu = ONUDevice()
+        self.onu.pon_port = self.pon_port
+        self.onu.serial_number = "BRCM1234"
+
+        self.tt_si = TtWorkflowDriverServiceInstance(
+            serial_number="BRCM1234",
+            owner=self.volt,
+            owner_id=self.volt.id,
+            of_dpid="of:1234"
+        )
+
+        self.whitelist_entry = TtWorkflowDriverWhiteListEntry(
+            serial_number="BRCM1234",
+            owner=self.volt,
+            owner_id=self.volt.id,
+            pon_port_id=1234,
+            device_id="of:1234"
+        )
+
+
+    def tearDown(self):
+        sys.path = self.sys_path_save
+
+    def test_not_in_whitelist(self):
+
+        with patch.object(TtWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_mock:
+            whitelist_mock.return_value = []
+
+            [res, message] = self.helpers.validate_onu(self.model_accessor, self.log, self.tt_si)
+
+            self.assertFalse(res)
+            self.assertEqual(message, "ONU not found in whitelist")
+
+    def test_wrong_location_port(self):
+        self.pon_port.port_no = 666
+        with patch.object(TtWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_mock, \
+            patch.object(ONUDevice.objects, "get_items") as onu_mock:
+            whitelist_mock.return_value = [self.whitelist_entry]
+            onu_mock.return_value = [self.onu]
+
+            [res, message] = self.helpers.validate_onu(self.model_accessor, self.log, self.tt_si)
+
+            self.assertFalse(res)
+            self.assertEqual(message, "ONU activated in wrong location")
+
+    def test_wrong_location_device(self):
+        self.tt_si.of_dpid = 666
+        with patch.object(TtWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_mock, \
+            patch.object(ONUDevice.objects, "get_items") as onu_mock:
+            whitelist_mock.return_value = [self.whitelist_entry]
+            onu_mock.return_value = [self.onu]
+
+            [res, message] = self.helpers.validate_onu(self.model_accessor, self.log, self.tt_si)
+
+            self.assertFalse(res)
+            self.assertEqual(message, "ONU activated in wrong location")
+
+    def test_deferred_validation(self):
+        with patch.object(TtWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_mock, \
+            patch.object(ONUDevice.objects, "get_items") as onu_mock:
+            whitelist_mock.return_value = [self.whitelist_entry]
+            onu_mock.return_value = []
+
+            with self.assertRaises(Exception) as e:
+                self.helpers.validate_onu(self.model_accessor, self.log, self.tt_si)
+
+            self.assertEqual(e.exception.message, "ONU device %s is not know to XOS yet" % self.tt_si.serial_number)
+
+    def test_validating_onu(self):
+        with patch.object(TtWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_mock, \
+            patch.object(ONUDevice.objects, "get_items") as onu_mock:
+            whitelist_mock.return_value = [self.whitelist_entry]
+            onu_mock.return_value = [self.onu]
+
+            [res, message] = self.helpers.validate_onu(self.model_accessor, self.log, self.tt_si)
+
+            self.assertTrue(res)
+            self.assertEqual(message, "ONU has been validated")
+
+    def test_validating_onu_lowercase(self):
+        self.whitelist_entry.serial_number = "brcm1234"
+        with patch.object(TtWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_mock, \
+            patch.object(ONUDevice.objects, "get_items") as onu_mock:
+            whitelist_mock.return_value = [self.whitelist_entry]
+            onu_mock.return_value = [self.onu]
+
+            [res, message] = self.helpers.validate_onu(self.model_accessor, self.log, self.tt_si)
+
+            self.assertTrue(res)
+            self.assertEqual(message, "ONU has been validated")
+
+if __name__ == '__main__':
+    unittest.main()
\ No newline at end of file
diff --git a/xos/synchronizer/tt-workflow-driver-synchronizer.py b/xos/synchronizer/tt-workflow-driver-synchronizer.py
new file mode 100644
index 0000000..9b420e7
--- /dev/null
+++ b/xos/synchronizer/tt-workflow-driver-synchronizer.py
@@ -0,0 +1,34 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+#!/usr/bin/env python
+
+# This imports and runs ../../xos-observer.py
+
+import os
+from xossynchronizer import Synchronizer
+from xosconfig import Config
+
+
+base_config_file = os.path.abspath(os.path.dirname(os.path.realpath(__file__)) + '/config.yaml')
+mounted_config_file = os.path.abspath(os.path.dirname(os.path.realpath(__file__)) + '/mounted_config.yaml')
+
+if os.path.isfile(mounted_config_file):
+    Config.init(base_config_file, 'synchronizer-config-schema.yaml', mounted_config_file)
+else:
+    Config.init(base_config_file, 'synchronizer-config-schema.yaml')
+
+Synchronizer().run()
\ No newline at end of file
diff --git a/xos/unittest.cfg b/xos/unittest.cfg
new file mode 100644
index 0000000..3db2d53
--- /dev/null
+++ b/xos/unittest.cfg
@@ -0,0 +1,14 @@
+[unittest]
+plugins=nose2.plugins.junitxml
+code-directories=synchronizer
+                 model_policies
+                 steps
+                 pull_steps
+                 event_steps
+
+[coverage]
+always-on = True
+coverage = synchronizer
+coverage-report = term
+coverage-report = html
+coverage-report = xml