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Add new external network in Openstack (Icehouse).

Just another one note to remember how to…


In my case a new external network it is private subnet with NAT in public addresses.

1) Let’s make a backup of neutron config files.

2) Add a new vlan nterface for our private subnet. No ip address set.

3) Edit neutron server configuration:

In /etc/neutron/plugins/ml2/ml2_conf.ini add a new external network info.

network_vlan_ranges = physnet1:1:4094,extnet1,extnet2,extnet3,extnet4
bridge_mappings = extnet1:br-ex,extnet2:br-ex-2,extnet3:br-ex-3,extnet4:br-ex-4

Here in network_vlan_ranges I added extnet3 и extnet4 and appropriate mapping in bridge_mappings – extnet3:br-ex-3,extnet4:br-ex-4.

extnet4 added for future use. When we face a lack of any free IPs in extnet3 we can add new external network without neutron-server service restart.


4) Create a new OVS bridge and add the vlan interface from step 2 as a new port on the bridge:

ovs-vsctl add-br br-ex-3
ovs-vsctl add-port br-ex-3 vlan1315

One more OVS bridge for future use:
ovs-vsctl add-br br-ex-4

5) Restart neutron services on openstack controller node (in my case controller node and network node is the same node).

Restart services below :


6) Create a new external network in Openstack.

First create a network:

neutron net-create "Ext_net_vlan1315" --provider:physical_network extnet3 \

--provider:network_type flat --router:external True --tenant-id <admin tenant ID>

and now create a subnet:

neutron subnet-create <network ID> --gateway \

--allocation-pool start=,end= --disable-dhcp


That’s it! Now we can use our new extnet3 external network to assign floating IPs and set virtual routers gateways.

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