+ default: 'ipam:neutron_plugin_contrail.plugins.opencontrail.contrail_plugin_ipam.NeutronPluginContrailIpam,policy:neutron_plugin_contrail.plugins.opencontrail.contrail_plugin_policy.NeutronPluginContrailPolicy,route-table:neutron_plugin_contrail.plugins.opencontrail.contrail_plugin_vpc.NeutronPluginContrailVpc,contrail:None'