[openstack-dev] [Openstack-operators] [Neutron] allow_overlapping_ips
Neil.Jerram at metaswitch.com
Wed Mar 25 17:09:27 UTC 2015
Salvatore Orlando <sorlando at nicira.com> writes:
> On 25 March 2015 at 17:36, Neil Jerram <Neil.Jerram at metaswitch.com>
> Kevin Benton <blak111 at gmail.com> writes:
> > This is a nice option for smaller deployments that didn't need
> > complexity of NAT. From a custom L3 plugin perspective, it also
> > eliminated any single points of failure pretty easily since no
> > state had to be distributed.
> > However, it was difficult to use with tenant self-service since
> > tenant could create a subnet that ate up the whole routing
> space. It
> > basically required that the networking was done by an admin or
> > the entire deployment was shared by a group of users trusted to
> do the
> > right thing.
> > My main interest in the IPAM work was to support fully routable
> > deployments like this. Once IPAM has a workflow that covers
> > subnet allocation from a subnet pool shared by the whole
> deployment, I
> > think deprecation of the "allow_overlapping_ips" option makes
> > sense since the operator can just create a single global subnet
> > to simulate it.
> I'm not defending allow_overlapping_ips, but I'm afraid I don't
> understand your point. In the future where "IPAM has a workflow
> covers tenant subnet allocation from a subnet pool shared by the
> deployment" and "the operator [creates] a single global subnet
> what will prevent a tenant from allocating a very large subnet of
> address space?
> For this specific item - shared subnet pools come with a quota
> mechanism, which ensure each tenant won't get more than a given share
> of the pool.
> This mechanism is still under review , we hope to be able to
> complete the review for the Kilo release.
>  https://review.openstack.org/#/c/165264/
Ah, so the new allocation_quota is an important factor here too. Many
thanks for explaining that!
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