text: # Copyright (c) 2013 OpenStack Foundation
  # All Rights Reserved.
  #
  #    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 oslo_log import log
  
  from neutron.common import exceptions as exc
  from neutron.i18n import _LI
  from neutron.plugins.common import constants as p_const
  from neutron.plugins.ml2 import driver_api as api
  
  LOG = log.getLogger(__name__)
  
  
  class LocalTypeDriver(api.TypeDriver):
      """Manage state for local networks with ML2.
  
      The LocalTypeDriver implements the 'local' network_type. Local
      network segments provide connectivity between VMs and other
      devices running on the same node, provided that a common local
      network bridging technology is available to those devices. Local
      network segments do not provide any connectivity between nodes.
      """
  
      def __init__(self):
          LOG.info(_LI("ML2 LocalTypeDriver initialization complete"))
  
      def get_type(self):
          return p_const.TYPE_LOCAL
  
      def initialize(self):
          pass
  
      def is_partial_segment(self, segment):
          return False
  
      def validate_provider_segment(self, segment):
          for key, value in segment.iteritems():
              if value and key != api.NETWORK_TYPE:
                  msg = _("%s prohibited for local provider network") % key
                  raise exc.InvalidInput(error_message=msg)
  
      def reserve_provider_segment(self, session, segment):
          # No resources to reserve
          return segment
  
      def allocate_tenant_segment(self, session):
          # No resources to allocate
          return {api.NETWORK_TYPE: p_const.TYPE_LOCAL}
  
      def release_segment(self, session, segment):
          # No resources to release
          pass
  
      def get_mtu(self, physical_network=None):
          pass
  