[Openstack-operators] DVR and public IP consumption

Carl Baldwin carl at ecbaldwin.net
Tue Jan 26 12:14:27 UTC 2016

On Thu, Jan 14, 2016 at 2:45 AM, Tomas Vondra <vondra at czech-itc.cz> wrote:
> Hi!
> I have just deployed an OpenStack Kilo installation with DVR and expected
> that it will consume one Public IP per network node as per
> http://assafmuller.com/2015/04/15/distributed-virtual-routing-floating-ips/,
> but it still eats one per virtual Router.
> What is the correct behavior?

Regardless of DVR, a Neutron router burns one IP per virtual router
which it uses to SNAT traffic from instances that do not have floating

When you use DVR, an additional IP is consumed for each compute host
running an L3 agent in DVR mode.  There has been some discussion about
how this can be eliminated but no action has been taken to do this.

> Otherwise, it works as a DVR should according to documentation. There are
> router namespaces at both compute and network nodes, snat namespaces at the
> network nodes and fip namespaces at the compute nodes. Every router has a
> router_interface_distributed and a router_centralized_snat with private IPs,
> however the router_gateway has a public IP, which I would like to getr id of
> to increase density.

I'm not sure if it is possible to avoid burning these IPs at this
time.  Maybe someone else can chime in with more detail.


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