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Unsure what bridges to create?

asked 2015-04-22 07:22:43 -0500

OmegaHarvest gravatar image

I'm currently following the OpenStack Juno guide for Ubuntu 14.04: (

The only bit I'm confused on is where to configure network bridges for use with OVS? From what I can tell, the guide only wants a bridge created for the external network on the network node. However, I'm unsure if I also have to create a bridge for the tunnel network between my compute node and network node? I keep reading about br-int for internal traffic in the OVS but am unsure if this actually needs creating in the interfaces file itself?

I'm attempting a three node setup.

Many Thanks


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answered 2015-04-23 07:35:24 -0500

jdexter gravatar image

OH, By convention, you would create a bridge for internal traffic, for your tunnels, and for each physical network device you have attached. For example if I had 2 flat interfaces eth1 and eth2, and then an IP for my tunneling on eth3, then my OVS bridges would look like br-int br-tun br-eth1 br-eth2

While there is no set way to name and organize the bridges it does help to keep things clean. Also if you are using the ovs-agent, it will want to know what bridge you are using for internal and for tunnels, as well as physical networks for providers networks.

 grep -v "#" /etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini | grep -v '^$'
network_vlan_ranges = physnet1
enable_tunneling = True
integration_bridge = br-int
tunnel_bridge = br-tun
local_ip =
bridge_mappings =physnet1:br-ex
polling_interval = 2
tunnel_types =vxlan
vxlan_udp_port =4789
l2_population = False
arp_responder = False
enable_distributed_routing = False
firewall_driver = neutron.agent.linux.iptables_firewall.OVSHybridIptablesFirewallDriver

As you can see in the example above br-int and br-tun are defined by the plugin, and provider network physnet1 is mapped to br-ex.
All of these bridges need to be created using the #ovs-vsctl add-br <bridge> or you will get errors on the startup of the ovs agent.

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Thank you. I now know what to create and how to check. I'm creating a GRE tunnel between my network node and my compute nodes. I understand I need to create br-int in the OVS for this. I'm assuming I don't need to create a bridge in the interfaces file for the tunnel, only for the external network?

OmegaHarvest gravatar imageOmegaHarvest ( 2015-04-23 08:35:48 -0500 )edit

answered 2015-04-23 07:49:18 -0500

The br-int bridge is automatically created in Juno and can be confirmed to exist by running ovs-vsctl list-br inside one of your nodes.

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That clears up a lot. Many Thanks!

OmegaHarvest gravatar imageOmegaHarvest ( 2015-04-23 08:31:08 -0500 )edit

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Asked: 2015-04-22 07:21:53 -0500

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Last updated: Apr 23 '15