libvirt users - Jul 2016 - Network without forward mode

Hey!

Another question. The documentation about networks say:

╭─────┤ http://libvirt.org/formatnetwork.html#elementsConnect ├─────
│Inclusion of the forward element indicates that the virtual network is
│to be connected to the physical LAN.Since 0.3.0. The mode attribute
│determines the method of forwarding. If there is no forward element, the
│network will be isolated from any other network (unless a guest
│connected to that network is acting as a router, of course).
╰─────

That's exactly what I want: just a vnet interface, no bridge, no
routing, no forwarding. However, if I create a network with just that:

#v+
<network>
  <name>public</name>
  <uuid>4629ba54-9e33-4a1f-9e45-78a1c8faaddc</uuid>
</network>
#v-

libvirt (2.0.0) adds a bridge stanza:

#v+
<network>
  <name>public</name>
  <uuid>4629ba54-9e33-4a1f-9e45-78a1c8faaddc</uuid>
  <bridge name='virbr1' stp='on' delay='0'/>
  <mac address='52:54:00:15:45:da'/>
</network>
#v-

The bridge is created. If I spawn a VM attached to this network, it gets
added to the bridge. Any way to have a network where absolutely no setup
is done?

Thanks!
-- 
Use the "telephone test" for readability.
            - The Elements of Programming Style (Kernighan & Plauger)

On Sun, Jul 24, 2016 at 11:18:19PM +0200, Vincent Bernat
wrote:
>Hey!
>
>Another question. The documentation about networks say:
>
>╭─────┤ http://libvirt.org/formatnetwork.html#elementsConnect ├─────
>│Inclusion of the forward element indicates that the virtual network is
>│to be connected to the physical LAN.Since 0.3.0. The mode attribute
>│determines the method of forwarding. If there is no forward element, the
>│network will be isolated from any other network (unless a guest
>│connected to that network is acting as a router, of course).
>╰─────
>
>That's exactly what I want: just a vnet interface, no bridge, no
>routing, no forwarding. However, if I create a network with just that:
>
"Just a vnet interface, no bridge" means you want no network.  Where
should the vnet be connected?
>#v+
><network>
>  <name>public</name>
>  <uuid>4629ba54-9e33-4a1f-9e45-78a1c8faaddc</uuid>
></network>
>#v-
>
>libvirt (2.0.0) adds a bridge stanza:
>
>#v+
><network>
>  <name>public</name>
>  <uuid>4629ba54-9e33-4a1f-9e45-78a1c8faaddc</uuid>
>  <bridge name='virbr1' stp='on' delay='0'/>
>  <mac address='52:54:00:15:45:da'/>
></network>
>#v-
>
Well yes, that's the bridge to connect to, otherwise you would have no
network.  How would the VMs connect to each other?  For the host to have
access to that network you would need another interface which is not
added.  This is an isolated network.
>The bridge is created. If I spawn a VM attached to this network, it gets
>added to the bridge. Any way to have a network where absolutely no setup
>is done?
>
Yes, have no network at all =)
You should probably describe your problem more closely.  Because based
on what you are saying you indeed want *no* network at all.
>Thanks!
>--
>Use the "telephone test" for readability.
>            - The Elements of Programming Style (Kernighan & Plauger)
>
>_______________________________________________
>libvirt-users mailing list
>libvirt-users@redhat.com
>https://www.redhat.com/mailman/listinfo/libvirt-users

❦ 25 juillet 2016 06:06 CEST, Martin Kletzander <mkletzan@redhat.com> :
>>╭─────┤ http://libvirt.org/formatnetwork.html#elementsConnect ├─────
>>│Inclusion of the forward element indicates that the virtual network is
>>│to be connected to the physical LAN.Since 0.3.0. The mode attribute
>>│determines the method of forwarding. If there is no forward element,
the
>>│network will be isolated from any other network (unless a guest
>>│connected to that network is acting as a router, of course).
>>╰─────
>>
>>That's exactly what I want: just a vnet interface, no bridge, no
>>routing, no forwarding. However, if I create a network with just that:
>>
>
> "Just a vnet interface, no bridge" means you want no network. 
Where
> should the vnet be connected?
The host is able to handle the routing. It seems I could just declare an
interface of type "ethernet" instead of "network" to get the
effect I
want.
-- 
Write clearly - don't be too clever.
            - The Elements of Programming Style (Kernighan & Plauger)