Trace Neutron code - neutron-server

 --> api/v2/router.py

1.       ext_mgr = extensions.PluginAwareExtensionManager.get_instance()

     ---> api/extensions.py

    get_instance()   

           get_extensions_path()  ===>  '/opt/stack/neutron/neutron/extensions'

           NeutronManager.get_service_plugins()  ===>

                   {'L3_ROUTER_NAT': <neutron.services.l3_router.l3_router_plugin.L3RouterPlugin object at 0x3322850>,

                    'CORE': <neutron.plugins.ml2.plugin.Ml2Plugin object at 0x3e5e5d0>,

                    'VPN': <neutron.services.vpn.plugin.VPNDriverPlugin object at 0x476bc50>,

                    'LOADBALANCER': <neutron.services.loadbalancer.plugin.LoadBalancerPlugin object at 0x4284410>,

                    'FIREWALL': <neutron.services.firewall.fwaas_plugin.FirewallPlugin object at 0x487d6d0>

                  }     

     
 2.       ext_mgr.extend_resources("2.0", attributes.RESOURCE_ATTRIBUTE_MAP)