Send a gratutious ARP when a v4 new address is added.

Change-Id: I51da87b40e1b68e1554c2ba1dd45838063dbf101
Closes-Bug: #1453201

akanda/router/drivers/ip.py

@@ -228,6 +228,13 @@ class IPManager(base.Manager):
             self.sudo(*fmt_args_add(item))
             self.up(interface)
 
+            # Send a gratuitous ARP for new v4 addressees
+            ip, prefix = item
+            if ip.version == 4:
+                utils.execute([
+                    'arping', '-A', '-c', '1', '-I', real_ifname, str(ip)
+                ], self.root_helper)
+
         for item in (prev_set - next_set):
             self.sudo(*fmt_args_delete(item))
             ip, prefix = item

ansible/tasks/base.yml

@@ -8,6 +8,7 @@
     - iptables-persistent
     - conntrack
     - ntp
+    - arping
 
 - name: latest bash (CVE-2014-6271)
   apt: name=bash state=latest install_recommends=no

test/unit/drivers/test_ip.py

@@ -259,6 +259,9 @@ class IPTestCase(TestCase):
                 ], 'sudo'),
                 mock.call([cmd, 'link', 'set', 'em0', 'up'], 'sudo'),
                 mock.call([cmd, 'addr', 'show', 'em0']),
+                mock.call([
+                    'arping', '-A', '-c', '1', '-I', 'em0', '192.168.105.2'
+                ], 'sudo'),
                 mock.call([
                     cmd, '-6', 'addr', 'add',
                     'fdca:3ba5:a17a:acda:20c:29ff:fe94:723d/64', 'dev', 'em0'
@@ -314,6 +317,9 @@ class IPTestCase(TestCase):
                 ], 'sudo'),
                 mock.call(['/sbin/ip', 'link', 'set', 'em0', 'up'], 'sudo'),
                 mock.call(['/sbin/ip', 'addr', 'show', 'em0']),
+                mock.call([
+                    'arping', '-A', '-c', '1', '-I', 'em0', str(a.ip)
+                ], 'sudo'),
                 mock.call([
                     '/sbin/ip', 'addr', 'del', str(c), 'dev', 'em0'
                 ], 'sudo'),