Add shim extension for ECMP

Related-Bug: #1880532
Change-Id: I5c5a2431117ec0381b0ad8058863ccb379d943fd

neutron_lib/api/definitions/__init__.py

@@ -33,6 +33,7 @@ from neutron_lib.api.definitions import dns
 from neutron_lib.api.definitions import dns_domain_keywords
 from neutron_lib.api.definitions import dns_domain_ports
 from neutron_lib.api.definitions import dvr
+from neutron_lib.api.definitions import ecmp_routes
 from neutron_lib.api.definitions import empty_string_filtering
 from neutron_lib.api.definitions import expose_l3_conntrack_helper
 from neutron_lib.api.definitions import expose_port_forwarding_in_fip
@@ -152,6 +153,7 @@ _ALL_API_DEFINITIONS = {
     dns_domain_keywords,
     dns_domain_ports,
     dvr,
+    ecmp_routes,
     empty_string_filtering,
     expose_l3_conntrack_helper,
     expose_port_forwarding_in_fip,

neutron_lib/api/definitions/ecmp_routes.py

@@ -0,0 +1,28 @@
+# 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.
+
+ALIAS = 'ecmp_routes'
+IS_SHIM_EXTENSION = True
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Equal Cost Multipath Routing'
+API_PREFIX = ''
+DESCRIPTION = ("Allows traffic to reach the"
+               "same destination via multiple different links ")
+UPDATED_TIMESTAMP = "2020-11-26T18:00:00-00:00"
+RESOURCE_ATTRIBUTE_MAP = {}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+ACTION_STATUS = {}
+REQUIRED_EXTENSIONS = []
+OPTIONAL_EXTENSIONS = []

releasenotes/notes/l3-support-ecmp-91a8aa61e3a73037.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  - The ``ecmp_routes`` extension API definition has been added as
+    ``neutron_lib.api.definitions.ecmp``.