Open Stack

Hi Yong, Gary,

Please put [Quantum] in the subject line for such emails, so it is easier
for team members to filter. I've edited the subject in this case.  More
thoughts inline.

On Fri, Jul 20, 2012 at 12:30 AM, Gary Kotton <gkotton at redhat.com> wrote:

> **
> Hi,
> Please see my comments below.
> Thanks
> Gary
>
>
> On 07/20/2012 03:07 AM, Yong Sheng Gong wrote:
>
>
> hi,
> I think the workflow can be this:
> 1. nova quantum api: allocate_for_instance(compute_host, device_id)
> 2.quantum-server: create_port(compute_host, device_id), we need to extend
> port model to include compute_host
>
>
> I think that this is problematic in a number of respects:
>     1. not sure how this will work for live migration (that is moving a VM
> that is running on host1 to host2)
>

Nova could probably update the port to point to a new host on live
migration.


>      2. I am not sure it would be wise to move this information to
> Quantum. What you have escibed may work for Quantum in OpenStack but
> Quantum in oVirt may behave differently. The API should be as generic as
> possible.
>
>
I agree that we want to be careful about this.  Quantum should be designed
such that it can work well with Nova, but I don't think the core API should
be nova-specific.  The core Quantum API will also be used to connect other
OpenStack services that need to plug into networks (e.g., load-balancer as
a service...) as well as other compute stacks all together (e.g., oVirt, as
mentioned by garyk).



> 4. plugin agent on compute_node: create tap device and attach it to
> bridge, set vlan and so on, return
>
> I'm worried that this is not sufficiently generic.  In several cases, it
is the compute platform that needs to create the device that represents the
vNIC.  My guess is that this model that you describe would primarily work
for libvirt type=ethernet, I believe, and that model has a several
limitations.  Other approaches that are better integrated with libvirt have
libvirt create and attach the device based on libvirt XML (checkout out
libvirt <interface> elements that have type=bridge or type=direct).  There
are also vif-drivers for other platforms like XenServer that definitely
don't go create tap devices.

I don't think this is sufficiently generic.  In several cases, it is the
compute platform that needs to create the device that represents the vNIC.
 My guess is that this model that you describe would primarily work for
libvirt type=ethernet, I believe, and that model has a several limitations.
 Other approaches that are better integrated with libvirt have libvirt
create and attach the device based on libvirt XML (checkout out libvirt
<interface> elements that have type=bridge or type=direct).  There are also
vif-drivers for other platforms like XenServer that definitely don't go
create tap devices.



> 5. quantum -server return the network information to nova, and then nova
> create VM.
>
> This workflow differentiates at:
> 1. tap device is not created by nova, it is created by plugin agent.  It
> will help us to use one unified vif-driver on the nova side for quantum.
>
>
For the same reasons I mentioned above, I believe the complexity of several
vif-drivers in nova, while undesirable, is actually difficult to avoid.


>
> For notification feature,  I hope keep it for metering's purpose.
>
>
> I do not think that we should mix the features. The metering is a feature
> that I think is used for billing. They may use the same infrastructure but
> I do not think that we may need different approaches for both.
>

There are many things that will need to trigger off basic Quantum events
(port creation/update/delete, floating ip allocation, etc.).  Even though
there will ultimately be different type of consumers (plugin agents,
services like DHCP/DNS, metering, troubleshooting/logging, etc.) I'm hoping
we can build a solid base notification mechanism that can be leveraged by
many/all of them.  If there are conflicting goals for different, perhaps we
cannot, but I think we should first discuss what those conflicting goals,
as they will inform our technical design.

Thanks,

Dan


> Thanks
> Yong Sheng Gong
>
>
>
>


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dan Wendlandt
Nicira, Inc: www.nicira.com
twitter: danwendlandt
~~~~~~~~~~~~~~~~~~~~~~~~~~~
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