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[ovs] br-ex confusion and neutron network

asked 2014-03-04 23:29:00 -0500

ssosothi gravatar image

updated 2014-03-05 01:21:04 -0500

Hello, I am slightly confused on which node to add br-ex and which port to add to it in my setup.

From my understanding I have to create br-ex and add the port with the external network access to it. However I have already created the bridge br-eth0 and added my only interface to it.

I am receiving the following error in /var/log/neutron/l3-agent.log

2014-03-04 23:05:10.927 1034 ERROR neutron.agent.l3_agent [-] The external network bridge 'br-ex' does not exist

My setup consists of 2 node both running openvswitch:

  • Controller&Networking Node: Connected to switch via eth0. eth0 is added to br-eth0 Bridge. br-eth0 has an address of
  • Compute Node: Conntected to switch via eth1. eth1 is added to br-eth0 Bridge. br-eth0 has an address of

I have launched 2 vm on the compute node with ip address of and These vm can ping each other, and running ip netns exec qdhcp-UUID ping on the Controller&Networking Node pings successfully. But pinging which is an external machine does not work.

My network diagram:

Thank you very much for your help.

Edit: Here's my current ovs-vsctl show. The incoming eth0 port is already added to br-eth0

root@nitrogen:~# sudo ovs-vsctl show
    Bridge br-int
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port "int-br-eth0"
            Interface "int-br-eth0"
        Port "tap13216f9c-9c"
            tag: 1
            Interface "tap13216f9c-9c"
                type: internal
        Port "qr-c52ae4a2-07"
            tag: 4095
            Interface "qr-c52ae4a2-07"
                type: internal
        Port br-int
            Interface br-int
                type: internal
        Port "tap7a41fbf5-d8"
            tag: 4095
            Interface "tap7a41fbf5-d8"
                type: internal
    Bridge br-tun
        Port "gre-5"
            Interface "gre-5"
                type: gre
                options: {in_key=flow, local_ip="", out_key=flow, remote_ip=""}
        Port br-tun
            Interface br-tun
                type: internal
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
    Bridge "br-eth0"
        Port "phy-br-eth0"
            Interface "phy-br-eth0"
        Port "eth0"
            Interface "eth0"
        Port "br-eth0"
            Interface "br-eth0"
                type: internal
    ovs_version: "1.10.2"
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answered 2014-03-05 00:13:16 -0500

RomilGupta gravatar image


You need to create br-ex on NN node where l3 agent is running to resolve the issue. If you are using Openvswitch then execute the following command to create the external bridge:

ovs-vsctl --may-exist add-br br-ex
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Thank you for your help. Will I need to add ports to this br-ex?

ssosothi gravatar imagessosothi ( 2014-03-05 01:16:49 -0500 )edit

Not required

RomilGupta gravatar imageRomilGupta ( 2014-03-05 12:37:47 -0500 )edit

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Asked: 2014-03-04 23:29:00 -0500

Seen: 7,486 times

Last updated: Mar 05 '14