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    <br>
    You most definitely do not need to destroy and re-create a VM just
    to add a 2nd network interface.<br>
    <br>
    I don't think those vnet interfaces got created by the host OS. I
    believe those are created by KVM (or libvirt) when you start a VM. I
    could be wrong though. But I just checked on my CentOS 6 KVM host
    machine and I see as many vnet interfaces as many VMs are currently
    running (or if one VM has two virtual network cards then of course
    that VM results two vnet interfaces shown on the host). Here the
    relevant part from one such VM's XML file (those XML files are under
    the /etc/libvirt/qemu directory on my CentOS host ) :<br>
    <br>
        &lt;interface type='bridge'&gt;<br>
          &lt;mac address='00:16:36:e2:20:ea'/&gt;<br>
          &lt;source bridge='br0'/&gt;<br>
          &lt;model type='virtio'/&gt;<br>
          &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x03'
    function='0x0'/&gt;<br>
        &lt;/interface&gt;<br>
        &lt;interface type='bridge'&gt;<br>
          &lt;mac address='00:16:36:e2:20:eb'/&gt;<br>
          &lt;source bridge='br600'/&gt;<br>
          &lt;model type='virtio'/&gt;<br>
          &lt;address type='pci' domain='0x0000' bus='0x00' slot='0x06'
    function='0x0'/&gt;<br>
        &lt;/interface&gt;<br>
    <br>
    As you can see, there are two interfaces defined in this VM's XML
    file. One is connected to the host's br0 interface and the 2nd is
    connected to the host's br600 interface. You must make sure that all
    your mac addesses are unique on your network though!!<br>
    <br>
    After editing a VM's XML file with your favorite editor, you need to
    execute this command:<br>
    virsh define /etc/libvirt/qemu/<i>your-vm-name</i>.xml<br>
    or just simply use this editor:<br>
    virsh edit <i>your-vm-name</i><br>
    (but I hate vi, so I use my favorite editor and when I finished
    editing I just run virsh define.)<br>
    <br>
    I edited VM's XML files many times and I can add/remove virtual
    network cards without problems.<br>
    <br>
    Zoltan<br>
    <br>
    <div class="moz-cite-prefix">On 12/9/2015 9:55 AM, Howard Leadmon
      wrote:<br>
    </div>
    <blockquote cite="mid:00f201d1325f$6891e9d0$39b5bd70$@leadmon.net"
      type="cite">
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        <p class="MsoNormal"><a moz-do-not-send="true"
            name="_MailEndCompose"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D">
              Tried that as well, but this has to be something that gets
              set at the OS level and loaded, as if you look at dmesg
              output, you can see all the vnet?? nodes as the OS comes
              online.    So the question is, what is virt-install doing
              that creates the needed vnet interface that is part of the
              bridge.   I really had to kill and reload the VM just to
              load a second interface..<o:p></o:p></span></a></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D"><o:p> </o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D"><o:p> </o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:10.5pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D">---<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:10.5pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D">Howard
            Leadmon </span><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D"><o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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          0in 0in 4.0pt">
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              1.0pt;padding:3.0pt 0in 0in 0in">
              <p class="MsoNormal"><b><span
                    style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">
                  <a class="moz-txt-link-abbreviated" href="mailto:centos-virt-bounces@centos.org">centos-virt-bounces@centos.org</a>
                  [<a class="moz-txt-link-freetext" href="mailto:centos-virt-bounces@centos.org">mailto:centos-virt-bounces@centos.org</a>] <b>On Behalf
                    Of </b>Zoltan Frombach<br>
                  <b>Sent:</b> Wednesday, December 9, 2015 2:42 AM<br>
                  <b>To:</b> Discussion about the virtualization on
                  CentOS <a class="moz-txt-link-rfc2396E" href="mailto:centos-virt@centos.org">&lt;centos-virt@centos.org&gt;</a><br>
                  <b>Subject:</b> Re: [CentOS-virt] How to manually add
                  a new interface to a bridge device?<o:p></o:p></span></p>
            </div>
          </div>
          <p class="MsoNormal"><o:p> </o:p></p>
          <p>I would stop the VM, edit its definition file (that's an
            XML file) and then start it up. But be careful: After you
            edit the XML file, you need to execute a command so KVM
            re-reads that file. I forgot that command, but you can look
            it up on Google.<o:p></o:p></p>
          <div>
            <p class="MsoNormal">On Dec 9, 2015 7:52 AM, "Howard
              Leadmon" &lt;<a moz-do-not-send="true"
                href="mailto:howard@leadmon.net">howard@leadmon.net</a>&gt;
              wrote:<o:p></o:p></p>
            <blockquote style="border:none;border-left:solid #CCCCCC
              1.0pt;padding:0in 0in 0in
              6.0pt;margin-left:4.8pt;margin-right:0in">
              <div>
                <div>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Maybe
                    my google-fu is failing me, but I have spent the
                    past couple hours looking at how to add a vnet?
                    Device to my KVM host running CentOS 6, and for the
                    life of me I can’t get this going.    <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">From
                    all my research if I want to add a device I should
                    just do ‘brctl addif br1 vnet14’ if I want to add a
                    vnet14 to bridge br1.   When I do this, I get:<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">#
                    brctl addif br0 vnet14<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">interface
                    vnet14 does not exist!<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">If
                    I run a ‘brctl show’ I get the following:<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">#
                    brctl show<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">bridge
                    name     bridge id               STP enabled    
                    interfaces<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">br0            
                    8000.00237dd22a4c       no              eth0<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet0<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet10<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet11<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet13<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet2<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       vnet3<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet4<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet6<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet8<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">br1     
                           8000.00237dd22a50       no              eth1<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet1<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet12<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet5<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                
                                                           vnet7<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">                                                       
                    vnet9<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Needless
                    to say the existing vnet?? Devices are in use on
                    guest VM’s currently.<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">When
                    I create a new VM using virt-install, I usually add
                    the following to my command line:<o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black">--network=bridge:br0
                      --network=bridge:br1</span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black"> </span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black">I messed up building a new VM,
                      and only added the br0 interface to the VM, but
                      need the br1 interface as well.  So my question
                      is, or a pointer to how I can add that br1
                      interface to my existing VM, and create the needed
                      vnet14 interface for it to attach to?</span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black"> </span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black">If anyone can explain how to
                      do this, or give me a good pointer on where the
                      info is on how to do this, it would sure be a huge
                      help..</span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black"> </span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="color:black">Thanks…</span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="font-size:10.5pt;color:#1F497D">---</span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
                      style="font-size:10.5pt;color:#1F497D">Howard
                      Leadmon </span><o:p></o:p></p>
                  <p class="MsoNormal"
                    style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
                </div>
              </div>
              <p class="MsoNormal" style="margin-bottom:12.0pt"><br>
                _______________________________________________<br>
                CentOS-virt mailing list<br>
                <a moz-do-not-send="true"
                  href="mailto:CentOS-virt@centos.org">CentOS-virt@centos.org</a><br>
                <a moz-do-not-send="true"
                  href="https://lists.centos.org/mailman/listinfo/centos-virt"
                  target="_blank">https://lists.centos.org/mailman/listinfo/centos-virt</a><o:p></o:p></p>
            </blockquote>
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      <br>
      <pre wrap="">_______________________________________________
CentOS-virt mailing list
<a class="moz-txt-link-abbreviated" href="mailto:CentOS-virt@centos.org">CentOS-virt@centos.org</a>
<a class="moz-txt-link-freetext" href="https://lists.centos.org/mailman/listinfo/centos-virt">https://lists.centos.org/mailman/listinfo/centos-virt</a>
</pre>
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