[Openstack-operators] [nova][neutron] What are your cells networking use cases?

John Garbutt john at johngarbutt.com
Thu Feb 25 10:36:42 UTC 2016

On 25 February 2016 at 10:01, Tim Bell <Tim.Bell at cern.ch> wrote:
> CERN info added.. Feel free to come back for more information if needed.
> Tim
> On 24/02/16 22:47, "Edgar Magana" <edgar.magana at workday.com> wrote:
>>It will be awesome if we can add this doc into the networking guide  :-)
>>On 2/24/16, 1:42 PM, "Matt Riedemann" <mriedem at linux.vnet.ibm.com> wrote:
>>>The nova and neutron teams are trying to sort out existing deployment
>>>network scenarios for cells v1 so we can try and document some of that
>>>and get an idea if things change at all with cells v2.
>>>Therefore we're asking that deployers running cells please document
>>>anything you can in an etherpad [1].
>>>We'll try to distill that for upstream docs at some point and then use
>>>it as a reference when talking about cells v2 + networking.
>>>[1] https://etherpad.openstack.org/p/cells-networking-use-cases

I certainly looks like most of the deployments have evolved from a
nova-network deploy in each child cell.

On the Rackspace side, I think carl baldwin's current plans should
allow our neutron and cells to sit together nicely:
* https://review.openstack.org/#/c/225384/ and

Attempt at a quick summary:
* networks can be split into L2 segments, each segment with its own
set of IP subnets
* port IP assignment delayed until it hits a specific L2 segment
* scheduling on the nova side that is IP capacity aware for unassigned ports
* re-used ports would keep their IP, so they must be attached in the
correct L2 segment (via boot or otherwise)
* new solution will not be fixed on cell boundaries

It would be great to get more feedback on the above approach, to see
if that meets your specific needs.


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