Change WAN Actions to use VIM config rules 61/7061/4
authorAnderson Bravalheri <a.bravalheri@bristol.ac.uk>
Fri, 7 Dec 2018 12:51:45 +0000 (12:51 +0000)
committerAnderson Bravalheri <a.bravalheri@bristol.ac.uk>
Fri, 18 Jan 2019 12:24:01 +0000 (12:24 +0000)
Extract switch ID and port by default from
vim.config.external_connections, as discussed in the WIM implementation
meeting (21/Nov/2018).

Change-Id: I95cc5fb0d6ad2822ef4bd1b80e7652bfabf34120
Signed-off-by: Anderson Bravalheri <a.bravalheri@bristol.ac.uk>
osm_ro/wim/errors.py
osm_ro/wim/tests/fixtures.py
osm_ro/wim/tests/test_actions.py
osm_ro/wim/wan_link_actions.py

index 16c53b5..ca8c2b7 100644 (file)
@@ -178,3 +178,12 @@ class WimAccountNotActive(HttpMappedError, KeyError):
         message += ('\nThe thread responsible for processing the actions have '
                     'suddenly stopped, or have never being spawned')
         super(WimAccountNotActive, self).__init__(message, http_code)
+
+
+class NoExternalPortFound(HttpMappedError):
+    """No external port associated to the instance_net"""
+
+    def __init__(self, instance_net):
+        super(NoExternalPortFound, self).__init__(
+            '{} uuid({})'.format(self.__class__.__doc__, instance_net['uuid']),
+            http_code=Not_Found)
index 1b52e49..1b0da4b 100644 (file)
@@ -36,7 +36,9 @@
 from __future__ import unicode_literals
 
 import json
+from itertools import izip
 from time import time
+from textwrap import wrap
 
 from six.moves import range
 
@@ -86,11 +88,28 @@ def wim_set(identifier=0, tenant=0):
     ]
 
 
-def datacenter(identifier):
+def _datacenter_to_switch_port(dc_id, port=None):
+    digits = 16
+    switch = ':'.join(wrap(('%0' + str(digits) + 'x') % int(dc_id), 2))
+    return (switch, str((port or int(dc_id)) + 1))
+
+
+def datacenter(identifier, external_ports_config=False):
+    config = '' if not external_ports_config else json.dumps({
+        'external_connections': [
+            {'condition': {
+                'provider:physical_network': 'provider',
+                'encapsulation_type': 'vlan'},
+                'vim_external_port':
+                dict(izip(('switch', 'port'),
+                          _datacenter_to_switch_port(identifier)))}
+        ]})
+
     return {'uuid': uuid('dc%d' % identifier),
             'name': 'dc%d' % identifier,
             'type': 'openvim',
-            'vim_url': 'localhost'}
+            'vim_url': 'localhost',
+            'config': config}
 
 
 def datacenter_account(datacenter, tenant):
@@ -107,7 +126,7 @@ def datacenter_tenant_association(datacenter, tenant):
                 uuid('dc-account%d%d' % (tenant, datacenter))}
 
 
-def datacenter_set(identifier, tenant):
+def datacenter_set(identifier=0, tenant=0):
     """Records necessary to create a datacenter and connect it to a tenant"""
     return [
         {'datacenters': [datacenter(identifier)]},
@@ -119,17 +138,19 @@ def datacenter_set(identifier, tenant):
 
 
 def wim_port_mapping(wim, datacenter,
-                     pop_dpid='AA:AA:AA:AA:AA:AA:AA:AA', pop_port=0,
-                     wan_dpid='BB:BB:BB:BB:BB:BB:BB:BB', wan_port=0):
+                     pop_dpid='AA:AA:AA:AA:AA:AA:AA:AA', pop_port=None,
+                     wan_dpid='BB:BB:BB:BB:BB:BB:BB:BB', wan_port=None):
     mapping_info = {'mapping_type': 'dpid-port',
                     'wan_switch_dpid': wan_dpid,
-                    'wan_switch_port': wan_port + datacenter + 1}
+                    'wan_switch_port': (str(wan_port) if wan_port else
+                                        str(int(datacenter) + int(wim) + 1))}
     id_ = 'dpid-port|' + sha1(json.dumps(mapping_info, sort_keys=True))
 
     return {'wim_id': uuid('wim%d' % wim),
             'datacenter_id': uuid('dc%d' % datacenter),
             'pop_switch_dpid': pop_dpid,
-            'pop_switch_port': pop_port + wim + 1,
+            'pop_switch_port': (str(pop_port) if pop_port else
+                                str(int(datacenter) + int(wim) + 1)),
             # ^  Datacenter router have one port managed by each WIM
             'wan_service_endpoint_id': id_,
             # ^  WIM managed router have one port connected to each DC
@@ -161,7 +182,8 @@ def processed_port_mapping(wim, datacenter,
 
 
 def consistent_set(num_wims=NUM_WIMS, num_tenants=NUM_TENANTS,
-                   num_datacenters=NUM_DATACENTERS):
+                   num_datacenters=NUM_DATACENTERS,
+                   external_ports_config=False):
     return [
         {'nfvo_tenants': [tenant(i) for i in range(num_tenants)]},
         {'wims': [wim(j) for j in range(num_wims)]},
@@ -176,7 +198,7 @@ def consistent_set(num_wims=NUM_WIMS, num_tenants=NUM_TENANTS,
             for j in range(num_wims)
         ]},
         {'datacenters': [
-            datacenter(k)
+            datacenter(k, external_ports_config)
             for k in range(num_datacenters)
         ]},
         {'datacenter_tenants': [
@@ -190,14 +212,15 @@ def consistent_set(num_wims=NUM_WIMS, num_tenants=NUM_TENANTS,
             for k in range(num_datacenters)
         ]},
         {'wim_port_mappings': [
-            wim_port_mapping(j, k)
+            (wim_port_mapping(j, k, *_datacenter_to_switch_port(k))
+             if external_ports_config else wim_port_mapping(j, k))
             for j in range(num_wims)
             for k in range(num_datacenters)
         ]},
     ]
 
 
-def instance_nets(num_datacenters=2, num_links=2):
+def instance_nets(num_datacenters=2, num_links=2, status='BUILD'):
     """Example of multi-site deploy with N datacenters and M WAN links between
     them (e.g M = 2 -> back and forth)
     """
@@ -209,7 +232,7 @@ def instance_nets(num_datacenters=2, num_links=2):
          # ^  instance_scenario_id == NS Record id
          'sce_net_id': uuid('vld%d' % l),
          # ^  scenario net id == VLD id
-         'status': 'BUILD',
+         'status': status,
          'vim_net_id': None,
          'created': True}
         for k in range(num_datacenters)
index 920182b..cee3c96 100644 (file)
@@ -47,7 +47,7 @@ from ...tests.db_helpers import (
     disable_foreign_keys,
     uuid,
 )
-from ..persistence import WimPersistence
+from ..persistence import WimPersistence, preprocess_record
 from ..wan_link_actions import WanLinkCreate, WanLinkDelete
 from ..wimconn import WimConnectorError
 
@@ -118,22 +118,118 @@ class TestCreate(TestActionsWithDb):
         self.assertIn('issue with the local networks', action.error_msg)
         self.assertIn('SCHEDULED_DELETION', action.error_msg)
 
+    def prepare_create__rules(self):
+        db_state = eg.consistent_set(num_wims=1, num_tenants=1,
+                                     num_datacenters=2,
+                                     external_ports_config=True)
+
+        instance_nets = eg.instance_nets(num_datacenters=2, num_links=1,
+                                         status='ACTIVE')
+        for i, net in enumerate(instance_nets):
+            net['vim_info'] = {}
+            net['vim_info']['provider:physical_network'] = 'provider'
+            net['vim_info']['encapsulation_type'] = 'vlan'
+            net['vim_info']['encapsulation_id'] = i
+            net['sdn_net_id'] = uuid('sdn-net%d' % i)
+
+        instance_action = eg.instance_action(action_id='ACTION-000')
+
+        db_state += [
+            {'instance_wim_nets': eg.instance_wim_nets()},
+            {'instance_nets': [preprocess_record(r) for r in instance_nets]},
+            {'instance_actions': instance_action}]
+
+        action = WanLinkCreate(
+            eg.wim_actions('CREATE', action_id='ACTION-000')[0])
+        # --> ensure it is in the database for updates --> #
+        action_record = action.as_record()
+        action_record['extra'] = json.dumps(action_record['extra'])
+        db_state += [{'vim_wim_actions': action_record}]
+
+        return db_state, action
+
+    @disable_foreign_keys
+    def test_process__rules(self):
+        # Given we want 1 WAN link between 2 datacenters
+        # and the local network in each datacenter is already created
+        db_state, action = self.prepare_create__rules()
+        self.populate(db_state)
+
+        instance_action = self.persist.get_by_uuid(
+            'instance_actions', action.instance_action_id)
+        number_done = instance_action['number_done']
+        number_failed = instance_action['number_failed']
+
+        # If the connector works fine
+        with patch.object(self.connector, 'create_connectivity_service',
+                          lambda *_, **__: (uuid('random-id'), None)):
+            # When we try to process a CREATE action that refers to the same
+            # instance_scenario_id and sce_net_id
+            action.process(self.connector, self.persist, self.ovim)
+
+        # Then the action should be succeeded
+        db_action = self.persist.query_one('vim_wim_actions', WHERE={
+            'instance_action_id': action.instance_action_id,
+            'task_index': action.task_index})
+        self.assertEqual(db_action['status'], 'DONE')
+
+        instance_action = self.persist.get_by_uuid(
+            'instance_actions', action.instance_action_id)
+        self.assertEqual(instance_action['number_done'], number_done + 1)
+        self.assertEqual(instance_action['number_failed'], number_failed)
+
+    @disable_foreign_keys
+    def test_process__rules_fail(self):
+        # Given we want 1 WAN link between 2 datacenters
+        # and the local network in each datacenter is already created
+        db_state, action = self.prepare_create__rules()
+        self.populate(db_state)
+
+        instance_action = self.persist.get_by_uuid(
+            'instance_actions', action.instance_action_id)
+        number_done = instance_action['number_done']
+        number_failed = instance_action['number_failed']
+
+        # If the connector raises an error
+        with patch.object(self.connector, 'create_connectivity_service',
+                          MagicMock(side_effect=WimConnectorError('foobar'))):
+            # When we try to process a CREATE action that refers to the same
+            # instance_scenario_id and sce_net_id
+            action.process(self.connector, self.persist, self.ovim)
+
+        # Then the action should be fail
+        db_action = self.persist.query_one('vim_wim_actions', WHERE={
+            'instance_action_id': action.instance_action_id,
+            'task_index': action.task_index})
+        self.assertEqual(db_action['status'], 'FAILED')
+
+        instance_action = self.persist.get_by_uuid(
+            'instance_actions', action.instance_action_id)
+        self.assertEqual(instance_action['number_done'], number_done)
+        self.assertEqual(instance_action['number_failed'], number_failed + 1)
+
     def prepare_create__sdn(self):
-        db_state = [{'nfvo_tenants': eg.tenant()}] + eg.wim_set()
+        db_state = eg.consistent_set(num_wims=1, num_tenants=1,
+                                     num_datacenters=2,
+                                     external_ports_config=False)
+
+        # Make sure all port_mappings are predictable
+        switch = 'AA:AA:AA:AA:AA:AA:AA:AA'
+        port = 1
+        port_mappings = next(r['wim_port_mappings']
+                             for r in db_state if 'wim_port_mappings' in r)
+        for mapping in port_mappings:
+            mapping['pop_switch_dpid'] = switch
+            mapping['pop_switch_port'] = port
 
-        instance_nets = eg.instance_nets(num_datacenters=2, num_links=1)
-        port_mappings = [
-            eg.wim_port_mapping(0, 0),
-            eg.wim_port_mapping(0, 1)
-        ]
         instance_action = eg.instance_action(action_id='ACTION-000')
+        instance_nets = eg.instance_nets(num_datacenters=2, num_links=1,
+                                         status='ACTIVE')
         for i, net in enumerate(instance_nets):
-            net['status'] = 'ACTIVE'
             net['sdn_net_id'] = uuid('sdn-net%d' % i)
 
         db_state += [{'instance_nets': instance_nets},
                      {'instance_wim_nets': eg.instance_wim_nets()},
-                     {'wim_port_mappings': port_mappings},
                      {'instance_actions': instance_action}]
 
         action = WanLinkCreate(
@@ -141,15 +237,21 @@ class TestCreate(TestActionsWithDb):
         # --> ensure it is in the database for updates --> #
         action_record = action.as_record()
         action_record['extra'] = json.dumps(action_record['extra'])
-        self.populate([{'vim_wim_actions': action_record}])
+        db_state += [{'vim_wim_actions': action_record}]
 
-        return db_state, action
+        ovim_patch = patch.object(
+            self.ovim, 'get_ports', MagicMock(return_value=[{
+                'switch_dpid': switch,
+                'switch_port': port,
+            }]))
+
+        return db_state, action, ovim_patch
 
     @disable_foreign_keys
     def test_process__sdn(self):
         # Given we want 1 WAN link between 2 datacenters
         # and the local network in each datacenter is already created
-        db_state, action = self.prepare_create__sdn()
+        db_state, action, ovim_patch = self.prepare_create__sdn()
         self.populate(db_state)
 
         instance_action = self.persist.get_by_uuid(
@@ -161,12 +263,6 @@ class TestCreate(TestActionsWithDb):
             self.connector, 'create_connectivity_service',
             lambda *_, **__: (uuid('random-id'), None))
 
-        ovim_patch = patch.object(
-            self.ovim, 'get_ports', MagicMock(return_value=[{
-                'switch_dpid': 'AA:AA:AA:AA:AA:AA:AA:AA',
-                'switch_port': 1,
-            }]))
-
         # If the connector works fine
         with connector_patch, ovim_patch:
             # When we try to process a CREATE action that refers to the same
@@ -188,7 +284,7 @@ class TestCreate(TestActionsWithDb):
     def test_process__sdn_fail(self):
         # Given we want 1 WAN link between 2 datacenters
         # and the local network in each datacenter is already created
-        db_state, action = self.prepare_create__sdn()
+        db_state, action, ovim_patch = self.prepare_create__sdn()
         self.populate(db_state)
 
         instance_action = self.persist.get_by_uuid(
@@ -200,12 +296,6 @@ class TestCreate(TestActionsWithDb):
             self.connector, 'create_connectivity_service',
             MagicMock(side_effect=WimConnectorError('foobar')))
 
-        ovim_patch = patch.object(
-            self.ovim, 'get_ports', MagicMock(return_value=[{
-                'switch_dpid': 'AA:AA:AA:AA:AA:AA:AA:AA',
-                'switch_port': 1,
-            }]))
-
         # If the connector throws an error
         with connector_patch, ovim_patch:
             # When we try to process a CREATE action that refers to the same
@@ -243,29 +333,32 @@ class TestDelete(TestActionsWithDb):
         assert action.is_done
 
     def prepare_delete(self):
-        db_state = [{'nfvo_tenants': eg.tenant()}] + eg.wim_set()
+        db_state = eg.consistent_set(num_wims=1, num_tenants=1,
+                                     num_datacenters=2,
+                                     external_ports_config=True)
 
-        instance_nets = eg.instance_nets(num_datacenters=2, num_links=1)
-        port_mappings = [
-            eg.wim_port_mapping(0, 0),
-            eg.wim_port_mapping(0, 1)
-        ]
-        instance_action = eg.instance_action(action_id='ACTION-000')
+        instance_nets = eg.instance_nets(num_datacenters=2, num_links=1,
+                                         status='ACTIVE')
         for i, net in enumerate(instance_nets):
-            net['status'] = 'ACTIVE'
+            net['vim_info'] = {}
+            net['vim_info']['provider:physical_network'] = 'provider'
+            net['vim_info']['encapsulation_type'] = 'vlan'
+            net['vim_info']['encapsulation_id'] = i
             net['sdn_net_id'] = uuid('sdn-net%d' % i)
 
-        db_state += [{'instance_nets': instance_nets},
-                     {'instance_wim_nets': eg.instance_wim_nets()},
-                     {'wim_port_mappings': port_mappings},
-                     {'instance_actions': instance_action}]
+        instance_action = eg.instance_action(action_id='ACTION-000')
+
+        db_state += [
+            {'instance_wim_nets': eg.instance_wim_nets()},
+            {'instance_nets': [preprocess_record(r) for r in instance_nets]},
+            {'instance_actions': instance_action}]
 
         action = WanLinkDelete(
             eg.wim_actions('DELETE', action_id='ACTION-000')[0])
         # --> ensure it is in the database for updates --> #
         action_record = action.as_record()
         action_record['extra'] = json.dumps(action_record['extra'])
-        self.populate([{'vim_wim_actions': action_record}])
+        db_state += [{'vim_wim_actions': action_record}]
 
         return db_state, action
 
@@ -331,8 +424,9 @@ class TestDelete(TestActionsWithDb):
     def test_create_and_delete(self):
         # Given a CREATE action was well succeeded
         db_state, delete_action = self.prepare_delete()
-        delete_action.save(self.persist, task_index=1)
         self.populate(db_state)
+
+        delete_action.save(self.persist, task_index=1)
         create_action = self.create_action()
 
         connector_patch = patch.multiple(
@@ -341,13 +435,7 @@ class TestDelete(TestActionsWithDb):
             create_connectivity_service=(
                 lambda *_, **__: (uuid('random-id'), None)))
 
-        ovim_patch = patch.object(
-            self.ovim, 'get_ports', MagicMock(return_value=[{
-                'switch_dpid': 'AA:AA:AA:AA:AA:AA:AA:AA',
-                'switch_port': 1,
-            }]))
-
-        with connector_patch, ovim_patch:
+        with connector_patch:  # , ovim_patch:
             create_action.process(self.connector, self.persist, self.ovim)
 
         # When we try to process a CREATE action that refers to the same
index 61c6dd9..034e415 100644 (file)
 ##
 # pylint: disable=E1101,E0203,W0201
 import json
+from pprint import pformat
+from sys import exc_info
 from time import time
 
+from six import reraise
+
 from ..utils import filter_dict_keys as filter_keys
 from ..utils import merge_dicts, remove_none_items, safe_get, truncate
 from .actions import CreateAction, DeleteAction, FindAction
 from .errors import (
     InconsistentState,
-    MultipleRecordsFound,
     NoRecordFound,
+    NoExternalPortFound
 )
 from wimconn import WimConnectorError
 
@@ -157,60 +161,164 @@ class WanLinkCreate(RefreshMixin, CreateAction):
         Returns:
             dict: Record representing the wan_port_mapping associated to the
                   given instance_net. The expected fields are:
-                  **wim_id**, **datacenter_id**, **pop_switch_id** (the local
+                  **wim_id**, **datacenter_id**, **pop_switch_dpid** (the local
                   network is expected to be connected at this switch),
                   **pop_switch_port**, **wan_service_endpoint_id**,
                   **wan_service_mapping_info**.
         """
-        wim_account = persistence.get_wim_account_by(uuid=self.wim_account_id)
-
-        # TODO: make more generic to support networks that are not created with
-        # the SDN assist. This method should have a consistent way of getting
-        # the endpoint for all different types of networks used in the VIM
-        # (provider networks, SDN assist, overlay networks, ...)
-        if instance_net.get('sdn_net_id'):
-            return self._get_connection_point_info_sdn(
-                persistence, ovim, instance_net, wim_account['wim_id'])
-        else:
-            raise InconsistentState(
-                'The field `instance_nets.sdn_net_id` was expected to be '
-                'found in the database for the record %s after the network '
-                'become active, but it is still NULL', instance_net['uuid'])
+        # First, we need to find a route from the datacenter to the outside
+        # world. For that, we can use the rules given in the datacenter
+        # configuration:
+        datacenter_id = instance_net['datacenter_id']
+        datacenter = persistence.get_datacenter_by(datacenter_id)
+        rules = safe_get(datacenter, 'config.external_connections', {}) or {}
+        vim_info = instance_net.get('vim_info', {}) or {}
+        # Alternatively, we can look for it, using the SDN assist
+        external_port = (self._evaluate_rules(rules, vim_info) or
+                         self._get_port_sdn(ovim, instance_net))
+
+        if not external_port:
+            raise NoExternalPortFound(instance_net)
+
+        # Then, we find the WAN switch that is connected to this external port
+        try:
+            wim_account = persistence.get_wim_account_by(
+                uuid=self.wim_account_id)
+
+            criteria = {
+                'wim_id': wim_account['wim_id'],
+                'pop_switch_dpid': external_port[0],
+                'pop_switch_port': external_port[1],
+                'datacenter_id': datacenter_id}
+
+            wan_port_mapping = persistence.query_one(
+                FROM='wim_port_mappings',
+                WHERE=criteria)
+        except NoRecordFound:
+            ex = InconsistentState('No WIM port mapping found:'
+                                   'wim_account: {}\ncriteria:\n{}'.format(
+                                       self.wim_account_id, pformat(criteria)))
+            reraise(ex.__class__, ex, exc_info()[2])
+
+        # It is important to return encapsulation information if present
+        mapping = merge_dicts(
+            wan_port_mapping.get('wan_service_mapping_info'),
+            filter_keys(vim_info, ('encapsulation_type', 'encapsulation_id'))
+        )
+
+        return merge_dicts(wan_port_mapping, wan_service_mapping_info=mapping)
 
-    def _get_connection_point_info_sdn(self, persistence, ovim,
-                                       instance_net, wim_id):
+    def _get_port_sdn(self, ovim, instance_net):
         criteria = {'net_id': instance_net['sdn_net_id']}
-        local_port_mapping = ovim.get_ports(filter=criteria)
+        try:
+            local_port_mapping = ovim.get_ports(filter=criteria)
+
+            if local_port_mapping:
+                return (local_port_mapping[0]['switch_dpid'],
+                        local_port_mapping[0]['switch_port'])
+        except:  # noqa
+            self.logger.exception('Problems when calling OpenVIM')
+
+        self.logger.debug('No ports found using criteria:\n%r\n.', criteria)
+        return None
+
+    def _evaluate_rules(self, rules, vim_info):
+        """Given a ``vim_info`` dict from a ``instance_net`` record, evaluate
+        the set of rules provided during the VIM/datacenter registration to
+        determine an external port used to connect that VIM/datacenter to
+        other ones where different parts of the NS will be instantiated.
+
+        For example, considering a VIM/datacenter is registered like the
+        following::
+
+            vim_record = {
+              "uuid": ...
+              ...  # Other properties associated with the VIM/datacenter
+              "config": {
+                ...  # Other configuration
+                "external_connections": [
+                  {
+                    "condition": {
+                      "provider:physical_network": "provider_net1",
+                      ...  # This method will look up all the keys listed here
+                           # in the instance_nets.vim_info dict and compare the
+                           # values. When all the values match, the associated
+                           # vim_external_port will be selected.
+                    },
+                    "vim_external_port": {"switch": "switchA", "port": "portB"}
+                  },
+                  ...  # The user can provide as many rules as needed, however
+                       # only the first one to match will be applied.
+                ]
+              }
+            }
+
+        When an ``instance_net`` record is instantiated in that datacenter with
+        the following information::
+
+            instance_net = {
+              "uuid": ...
+              ...
+              "vim_info": {
+                ...
+                "provider_physical_network": "provider_net1",
+              }
+            }
 
-        if len(local_port_mapping) > 1:
-            raise MultipleRecordsFound(criteria, 'ovim.ports')
-        local_port_mapping = local_port_mapping[0]
+        Then, ``switchA`` and ``portB`` will be used to stablish the WAN
+        connection.
 
-        criteria = {
-            'wim_id': wim_id,
-            'pop_switch_dpid': local_port_mapping['switch_dpid'],
-            'pop_switch_port': local_port_mapping['switch_port'],
-            'datacenter_id': instance_net['datacenter_id']}
+        Arguments:
+            rules (list): Set of dicts containing the keys ``condition`` and
+                ``vim_external_port``. This list should be extracted from
+                ``vim['config']['external_connections']`` (as stored in the
+                database).
+            vim_info (dict): Information given by the VIM Connector, against
+               which the rules will be evaluated.
+
+        Returns:
+            tuple: switch id (local datacenter switch) and port or None if
+                the rule does not match.
+        """
+        rule = next((r for r in rules if self._evaluate_rule(r, vim_info)), {})
+        if 'vim_external_port' not in rule:
+            self.logger.debug('No external port found.\n'
+                              'rules:\n%r\nvim_info:\n%r\n\n', rules, vim_info)
+            return None
 
-        wan_port_mapping = persistence.query_one(
-            FROM='wim_port_mappings',
-            WHERE=criteria)
+        return (rule['vim_external_port']['switch'],
+                rule['vim_external_port']['port'])
 
-        if local_port_mapping.get('vlan'):
-            wan_port_mapping['wan_service_mapping_info']['vlan'] = (
-                local_port_mapping['vlan'])
+    @staticmethod
+    def _evaluate_rule(rule, vim_info):
+        """Evaluate the conditions from a single rule to ``vim_info`` and
+        determine if the rule should be applicable or not.
 
-        return wan_port_mapping
+        Please check :obj:`~._evaluate_rules` for more information.
+
+        Arguments:
+            rule (dict): Data structure containing the keys ``condition`` and
+                ``vim_external_port``. This should be one of the elements in
+                ``vim['config']['external_connections']`` (as stored in the
+                database).
+            vim_info (dict): Information given by the VIM Connector, against
+               which the rules will be evaluated.
+
+        Returns:
+            True or False: If all the conditions are met.
+        """
+        condition = rule.get('condition', {}) or {}
+        return all(safe_get(vim_info, k) == v for k, v in condition.items())
 
     @staticmethod
     def _derive_connection_point(wan_info):
         point = {'service_endpoint_id': wan_info['wan_service_endpoint_id']}
         # TODO: Cover other scenarios, e.g. VXLAN.
         details = wan_info.get('wan_service_mapping_info', {})
-        if 'vlan' in details:
+        if details.get('encapsulation_type') == 'vlan':
             point['service_endpoint_encapsulation_type'] = 'dot1q'
             point['service_endpoint_encapsulation_info'] = {
-                'vlan': details['vlan']
+                'vlan': details['encapsulation_id']
             }
         else:
             point['service_endpoint_encapsulation_type'] = 'none'
@@ -247,7 +355,8 @@ class WanLinkCreate(RefreshMixin, CreateAction):
                 connection_points
                 # TODO: other properties, e.g. bandwidth
             )
-        except (WimConnectorError, InconsistentState) as ex:
+        except (WimConnectorError, InconsistentState,
+                NoExternalPortFound) as ex:
             self.logger.exception(ex)
             return self.fail(
                 persistence,