Re: [Qemu-discuss] Network Migration During Live Migration

[Jakob Bohm]

On 02-02-2015 23:33, Azizul Hakim wrote:
> Does QEMU supports network migration during live migration? By network 
> migration I mean migrating open connections inside the VM so when the 
> VM moves to a new physical host, it can still  communicate with 
> outside world at the same fashion as it did before migration?
>
> I'm mainly interested in this issue as I've a Web Server running 
> inside the VM which I use using port forwarding and I would like to 
> know what should I do to keep the server working after the migration?
I am not sure if this will be helpful:

The general concept is that the virtual machine (including
its OS and network software) should be completely unaware
that the physical computer host has been replaced beneath
it.

Thus for networking, it should have the exact same MAC
address(es), IP address(es) and connectivity before and
after.  Whatever tool, script or procedure outside qemu
is used to command live migration is expected/required
to make this happen by specifying identical "inside"
network behavior (same virtual NIC model, MAC address
and virtual PCI bus location) and compatible "outside"
network behavior (e.g. bridging or other hookup to the
same VLAN).

Typically the your web server VM would be connected to
a bridged network which is available on both physical
machines and the effect would be as if you instantly
moved a physical web servers network cable from one
position in the outside network switch to another.
This way, even ongoing downloads from the web server
should not be disrupted, except for a short pause while
the migration slows down the VM and the physical network
switch learns the new path to its MAC address.

Enjoy

Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S.  http://www.wisemo.com
Transformervej 29, 2730 Herlev, Denmark.  Direct +45 31 13 16 10
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