Introduce PUBLIC_BRIDGE_MTU variable to set br-ex MTU

This variable can be used to accommodate for underlying infrastructure
that does not provide full 1500-sized traffic, or maybe instead gives
access to Jumbo frames.

Change-Id: I38a80bac18673a30842a7b997d0669fed5aff976
Related-Bug: #1603268

functions

@@ -637,6 +637,15 @@ function create_disk {
     fi
 }
 
+
+# set_mtu - Set MTU on a device
+function set_mtu {
+    local dev=$1
+    local mtu=$2
+    sudo ip link set mtu $mtu dev $dev
+}
+
+
 # Restore xtrace
 $_XTRACE_FUNCTIONS
 

lib/neutron_plugins/linuxbridge_agent

@@ -50,6 +50,7 @@ function neutron_plugin_configure_dhcp_agent {
 function neutron_plugin_configure_l3_agent {
     local conf_file=$1
     sudo brctl addbr $PUBLIC_BRIDGE
+    set_mtu $PUBLIC_BRIDGE $PUBLIC_BRIDGE_MTU
     iniset $conf_file DEFAULT external_network_bridge
     iniset $conf_file DEFAULT l3_agent_manager neutron.agent.l3_agent.L3NATAgentWithStateReport
 }

lib/neutron_plugins/openvswitch_agent

@@ -104,7 +104,7 @@ function neutron_plugin_configure_plugin_agent {
         sudo ovs-vsctl -- --may-exist add-port "br-$VLAN_INTERFACE" $VLAN_INTERFACE
 
         # Create external bridge and add port
-        _neutron_ovs_base_add_bridge $PUBLIC_BRIDGE
+        _neutron_ovs_base_add_public_bridge
         sudo ovs-vsctl -- --may-exist add-port $PUBLIC_BRIDGE $PUBLIC_INTERFACE
 
         # Set bridge mappings to "physnet1:br-$GUEST_INTERFACE_DEFAULT"

lib/neutron_plugins/ovs_base

@@ -105,11 +105,16 @@ function _neutron_ovs_base_configure_l3_agent {
         sudo ip link set $Q_PUBLIC_VETH_EX up
         sudo ip addr flush dev $Q_PUBLIC_VETH_EX
     else
-        _neutron_ovs_base_add_bridge $PUBLIC_BRIDGE
+        _neutron_ovs_base_add_public_bridge
         sudo ovs-vsctl br-set-external-id $PUBLIC_BRIDGE bridge-id $PUBLIC_BRIDGE
     fi
 }
 
+function _neutron_ovs_base_add_public_bridge {
+    _neutron_ovs_base_add_bridge $PUBLIC_BRIDGE
+    set_mtu $PUBLIC_BRIDGE $PUBLIC_BRIDGE_MTU
+}
+
 function _neutron_ovs_base_configure_nova_vif_driver {
     :
 }

lib/neutron_plugins/services/l3

@@ -15,6 +15,7 @@ IPV6_PROVIDER_FIXED_RANGE=${IPV6_PROVIDER_FIXED_RANGE:-}
 IPV6_PROVIDER_NETWORK_GATEWAY=${IPV6_PROVIDER_NETWORK_GATEWAY:-}
 
 PUBLIC_BRIDGE=${PUBLIC_BRIDGE:-br-ex}
+PUBLIC_BRIDGE_MTU=${PUBLIC_BRIDGE_MTU:-1500}
 
 # If Q_USE_PUBLIC_VETH=True, create and use a veth pair instead of
 # PUBLIC_BRIDGE.  This is intended to be used with