[openstack-dev] Fwd: FW: [Neutron] Group Based Policy and the way forward

Ryan Moats rmoats at us.ibm.com
Wed Aug 6 18:55:17 UTC 2014

Jay Pipes <jaypipes at gmail.com> wrote on 08/06/2014 01:04:41 PM:


> AFAICT, there is nothing that can be done with the GBP API that cannot
> be done with the low-level regular Neutron API.

I'll take you up on that, Jay :)

How exactly do I specify behavior between two collections of ports residing
in the same IP subnet (an example of this is a bump-in-the-wire network

I've looked around regular Neutron and all I've come up with so far is:
	(1) use security groups on the ports
	(2) set allow_overlapping_ips to true, set up two networks with
identical CIDR block subnets and disjoint allocation pools and put a
vRouter between them.

Now #1 only works for basic allow/deny access and adds the complexity of
needing to specify per-IP address security rules, which means you need the
ports to have IP addresses already and then manually add them into the
security groups, which doesn't seem particularly very orchestration

Now #2 handles both allow/deny access as well as provides a potential
attachment point for other behaviors, *but* you have to know to set up the
disjoint allocation pools, and your depending on your drivers to handle the
case of a router that isn't really a router (i.e. it's got two interfaces
in the same subnet, possibly with the same address (unless you thought of
that when you set things up)).

You can say that both of these are *possible*, but they both look more
complex to me than just having two groups of ports and specifying a policy
between them.

Ryan Moats
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