diff --git a/neutron/api/rpc/handlers/securitygroups_rpc.py b/neutron/api/rpc/handlers/securitygroups_rpc.py
index d1006d0158f..4d4d0fea82a 100644
--- a/neutron/api/rpc/handlers/securitygroups_rpc.py
+++ b/neutron/api/rpc/handlers/securitygroups_rpc.py
@@ -71,9 +71,11 @@ class SecurityGroupServerRpcCallback(object):
         :returns:
         sg_info{
           'security_groups': {sg_id: [rule1, rule2]}
-          'sg_member_ips': {sg_id: {'IPv4': [], 'IPv6': []}}
+          'sg_member_ips': {sg_id: {'IPv4': set(), 'IPv6': set()}}
           'devices': {device_id: {device_info}}
         }
+
+        Note that sets are serialized into lists by rpc code.
         """
         devices_info = kwargs.get('devices')
         ports = self._get_devices_info(devices_info)
diff --git a/neutron/db/securitygroups_rpc_base.py b/neutron/db/securitygroups_rpc_base.py
index e8f9292c71d..728312b5350 100644
--- a/neutron/db/securitygroups_rpc_base.py
+++ b/neutron/db/securitygroups_rpc_base.py
@@ -194,7 +194,8 @@ class SecurityGroupServerRpcMixin(sg_db.SecurityGroupDbMixin):
                 if remote_gid not in remote_security_group_info:
                     remote_security_group_info[remote_gid] = {}
                 if ethertype not in remote_security_group_info[remote_gid]:
-                    remote_security_group_info[remote_gid][ethertype] = []
+                    # this set will be serialized into a list by rpc code
+                    remote_security_group_info[remote_gid][ethertype] = set()
 
             direction = rule_in_db['direction']
             rule_dict = {
@@ -228,9 +229,8 @@ class SecurityGroupServerRpcMixin(sg_db.SecurityGroupDbMixin):
         for sg_id, member_ips in ips.items():
             for ip in member_ips:
                 ethertype = 'IPv%d' % netaddr.IPNetwork(ip).version
-                if (ethertype in sg_info['sg_member_ips'][sg_id]
-                    and ip not in sg_info['sg_member_ips'][sg_id][ethertype]):
-                    sg_info['sg_member_ips'][sg_id][ethertype].append(ip)
+                if ethertype in sg_info['sg_member_ips'][sg_id]:
+                    sg_info['sg_member_ips'][sg_id][ethertype].add(ip)
         return sg_info
 
     def _select_rules_for_ports(self, context, ports):
diff --git a/neutron/tests/unit/test_security_groups_rpc.py b/neutron/tests/unit/test_security_groups_rpc.py
index 50b8936e5af..138e742e55a 100644
--- a/neutron/tests/unit/test_security_groups_rpc.py
+++ b/neutron/tests/unit/test_security_groups_rpc.py
@@ -490,8 +490,8 @@ class SGServerRpcCallBackTestCase(test_sg.SecurityGroupDBTestCase):
                          'remote_group_id': sg2_id}
                     ]},
                     'sg_member_ips': {sg2_id: {
-                        'IPv4': [u'10.0.0.3'],
-                        'IPv6': [],
+                        'IPv4': set([u'10.0.0.3']),
+                        'IPv6': set(),
                     }}
                 }
                 self.assertEqual(expected['security_groups'],
@@ -626,7 +626,7 @@ class SGServerRpcCallBackTestCase(test_sg.SecurityGroupDBTestCase):
                          'remote_group_id': sg1_id}
                     ]},
                     'sg_member_ips': {sg1_id: {
-                        'IPv6': [],
+                        'IPv6': set(),
                     }}
                 }
                 self.assertEqual(expected['security_groups'],