[libvirt] netdev ethernet allow to specify ip address and routes

[Laine Stump]

On 03/31/2016 05:23 AM, Vasiliy Tolstov wrote:
> 2016-03-23 20:46 GMT+03:00 Laine Stump <laine at laine.org>:
>> Since there is no documentation included with the patch, and the wrong RNG
>> file has been modified, I'm not clear on exactly why a libvirt virtual
>> network would use a peer address.
>>
>> Normally libvirt networks are made by creating a bridge device, adding in
>> some iptables rules, and running an instance of dnsmasq to service dhcp and
>> dns requests made by guests who have tap devices connected to that network.
>> But if I understand correctly, your patches are intended to allow setting
>> the local and peer address for guest-connected tap devices that aren't
>> attached to a bridge on the host side, but instead rely on the host's IP
>> stack to route appropriate traffic through the tap device. If so, then why
>> is a libvirt network involved at all? Why/how could a bridge device be used
>> for a point-to-point link? If this isn't just a misunderstanding of which
>> parts of libvirt code affect what, then some examples (and patches to
>> formatdomain.html.in/formatnetwork.html.in) would be very useful to help me
>> understand.
>
> I'm send new patch with some docs in formatdomain.
> Sometimes bridges not allowed or not needed. We use plain tap devices
> on host side and bird routing daemon to route traffic to/from tap
> devices.
>

But the changes to network_conf.c, network_conf.h, and bridge_driver.c 
only serve to assign a POINTOPOINT IP address pair to *the bridge* of a 
libvirt-managed network. This is unrelated to any IP address pair 
assigned to a tap device used by an lxc or qemu domain.

I'll comment further in your new patch.