[openstack-dev] [neutron] Neutron scaling datapoints?

Neil Jerram Neil.Jerram at metaswitch.com
Thu Apr 9 15:22:50 UTC 2015

Hi Mike,

Many thanks for your reply!

On 08/04/15 17:56, Mike Spreitzer wrote:
> Are you looking at scaling the numbers of tenants, Neutron routers, and
> tenant networks as you scale hosts and guests?  I think this is a
> plausible way to grow.  The compartmentalizations that comes with
> growing those things may make a difference in results.

Are you thinking of control plane or data plane limits?  In my email I 
was thinking of control plane points, such as

- how many compute host agents can communicate with the Neutron server

- how many Neutron server instances or threads are needed

- whether there are any limits associated with the Neutron DB (unlikely 
I guess).

Does the use of tenant networks and routers affect those points, in your 
experience?  That would be less obvious to me than simply how many 
compute hosts or Neutron servers there are.

On the data plane side - if that was more what you meant - I can 
certainly see the limits there and how they are alleviated by using 
tenant networks and routers, in the L2 model.  FWIW, my project Calico 
[1] tries to avoid those by not providing a L2 domain at all - which can 
make sense for workloads that only require or provide IP services - and 
instead routing data through the fabric.

To answer your question, then, no, I wasn't thinking of scaling tenant 
networks and routers, per your suggestion, because Calico doesn't do 
things that way (or alternatively because Calico already routes 
everywhere), and because I didn't think that would be relevant to the 
control plane scaling that I had in mind.  But I may be missing 
something, so please do say if so.

Many thanks,

[1] http://www.projectcalico.org/

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