Allow setting MTU to 1500

There are times when it is desirable to set the MTU of an
"interface" to 1500 -- when the external network and the storage
network are different VLANs on the same physical interface, for
example.

Change-Id: Ic5ea6ad05118fd57c26c898a460c19969de4109d
Closes-Bug: #1539821

5 files changed, 23 insertions, 11 deletions

diff --git a/os_net_config/impl_eni.py b/os_net_config/impl_eni.py
index 68d91ef..ae60099 100644
--- a/os_net_config/impl_eni.py
+++ b/os_net_config/impl_eni.py
@@ -130,7 +130,7 @@ class ENINetConfig(os_net_config.NetConfig):
             data += "auto %s\n" % interface.name
             data += _iface
             data += address_data
-        if interface.mtu != 1500:
+        if interface.mtu:
             data += "    mtu %i\n" % interface.mtu
 
         if interface.hwaddr:
diff --git a/os_net_config/impl_ifcfg.py b/os_net_config/impl_ifcfg.py
index 70f5065..2e99f98 100644
--- a/os_net_config/impl_ifcfg.py
+++ b/os_net_config/impl_ifcfg.py
@@ -164,11 +164,11 @@ class IfcfgNetConfig(os_net_config.NetConfig):
                 data += "BOOTPROTO=dhcp\n"
             elif not base_opt.addresses:
                 data += "BOOTPROTO=none\n"
-        if base_opt.mtu != 1500:
+        if base_opt.mtu:
             data += "MTU=%i\n" % base_opt.mtu
         if base_opt.use_dhcpv6 or base_opt.v6_addresses():
             data += "IPV6INIT=yes\n"
-            if base_opt.mtu != 1500:
+            if base_opt.mtu:
                 data += "IPV6_MTU=%i\n" % base_opt.mtu
         if base_opt.use_dhcpv6:
             data += "DHCPV6C=yes\n"
diff --git a/os_net_config/objects.py b/os_net_config/objects.py
index dd8489e..b08dc46 100644
--- a/os_net_config/objects.py
+++ b/os_net_config/objects.py
@@ -134,7 +134,7 @@ class _BaseOpts(object):
     """Base abstraction for logical port options."""
 
     def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
-                 routes=None, mtu=1500, primary=False, nic_mapping=None,
+                 routes=None, mtu=None, primary=False, nic_mapping=None,
                  persist_mapping=False, defroute=True, dhclient_args=None,
                  dns_servers=None):
         addresses = addresses or []
@@ -192,7 +192,7 @@ class _BaseOpts(object):
                                                False)))
         defroute = strutils.bool_from_string(str(json.get('defroute',
                                              True)))
-        mtu = json.get('mtu', 1500)
+        mtu = json.get('mtu', None)
         dhclient_args = json.get('dhclient_args')
         dns_servers = json.get('dns_servers')
         primary = strutils.bool_from_string(str(json.get('primary', False)))
@@ -236,7 +236,7 @@ class Interface(_BaseOpts):
     """Base class for network interfaces."""
 
     def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
-                 routes=None, mtu=1500, primary=False, nic_mapping=None,
+                 routes=None, mtu=None, primary=False, nic_mapping=None,
                  persist_mapping=False, defroute=True, dhclient_args=None,
                  dns_servers=None):
         addresses = addresses or []
@@ -262,7 +262,7 @@ class Vlan(_BaseOpts):
     """
 
     def __init__(self, device, vlan_id, use_dhcp=False, use_dhcpv6=False,
-                 addresses=None, routes=None, mtu=1500, primary=False,
+                 addresses=None, routes=None, mtu=None, primary=False,
                  nic_mapping=None, persist_mapping=False, defroute=True,
                  dhclient_args=None, dns_servers=None):
         addresses = addresses or []
@@ -294,7 +294,7 @@ class OvsBridge(_BaseOpts):
     """Base class for OVS bridges."""
 
     def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
-                 routes=None, mtu=1500, members=None, ovs_options=None,
+                 routes=None, mtu=None, members=None, ovs_options=None,
                  ovs_extra=None, nic_mapping=None, persist_mapping=False,
                  defroute=True, dhclient_args=None, dns_servers=None):
         addresses = addresses or []
@@ -354,7 +354,7 @@ class LinuxBridge(_BaseOpts):
     """Base class for Linux bridges."""
 
     def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
-                 routes=None, mtu=1500, members=None, nic_mapping=None,
+                 routes=None, mtu=None, members=None, nic_mapping=None,
                  persist_mapping=False, defroute=True, dhclient_args=None,
                  dns_servers=None):
         addresses = addresses or []
@@ -409,7 +409,7 @@ class LinuxBond(_BaseOpts):
     """Base class for Linux bonds."""
 
     def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
-                 routes=None, mtu=1500, primary=False, members=None,
+                 routes=None, mtu=None, primary=False, members=None,
                  bonding_options=None, nic_mapping=None, persist_mapping=False,
                  defroute=True, dhclient_args=None, dns_servers=None):
         addresses = addresses or []
@@ -464,7 +464,7 @@ class OvsBond(_BaseOpts):
     """Base class for OVS bonds."""
 
     def __init__(self, name, use_dhcp=False, use_dhcpv6=False, addresses=None,
-                 routes=None, mtu=1500, primary=False, members=None,
+                 routes=None, mtu=None, primary=False, members=None,
                  ovs_options=None, ovs_extra=None, nic_mapping=None,
                  persist_mapping=False, defroute=True, dhclient_args=None,
                  dns_servers=None):
diff --git a/os_net_config/tests/test_impl_eni.py b/os_net_config/tests/test_impl_eni.py
index e0e009d..7f909ff 100644
--- a/os_net_config/tests/test_impl_eni.py
+++ b/os_net_config/tests/test_impl_eni.py
@@ -221,6 +221,12 @@ class TestENINetConfig(base.TestCase):
         self.provider.add_vlan(vlan)
         self.assertEqual(_VLAN_NO_IP, self.get_interface_config('vlan5'))
 
+    def test_vlan_mtu_1500(self):
+        vlan = objects.Vlan('eth0', 5, mtu=1500)
+        self.provider.add_vlan(vlan)
+        expected = _VLAN_NO_IP + '    mtu 1500\n'
+        self.assertEqual(expected, self.get_interface_config('vlan5'))
+
     def test_vlan_ovs_bridge_int_port(self):
         vlan = objects.Vlan('eth0', 5)
         bridge = objects.OvsBridge('br0', use_dhcp=True,
diff --git a/os_net_config/tests/test_impl_ifcfg.py b/os_net_config/tests/test_impl_ifcfg.py
index c914ea2..8a60a8d 100644
--- a/os_net_config/tests/test_impl_ifcfg.py
+++ b/os_net_config/tests/test_impl_ifcfg.py
@@ -359,6 +359,12 @@ class TestIfcfgNetConfig(base.TestCase):
         self.provider.add_vlan(vlan)
         self.assertEqual(_VLAN_OVS, self.get_interface_config('vlan5'))
 
+    def test_add_vlan_mtu_1500(self):
+        vlan = objects.Vlan('em1', 5, mtu=1500)
+        self.provider.add_vlan(vlan)
+        expected = _VLAN_NO_IP + 'MTU=1500\n'
+        self.assertEqual(expected, self.get_interface_config('vlan5'))
+
     def test_add_ovs_bridge_with_vlan(self):
         vlan = objects.Vlan('em1', 5)
         bridge = objects.OvsBridge('br-ctlplane', use_dhcp=True,