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The Quantum network manager included with recent versions of OpenStack does not support the --bridge and --bridge-interface arguments to the nova-list network create command. Short of writing a new Quantum plugin, is there any way to get Quantum to use existing bridge devices rather than creating new ones?

We are deploying OpenStack in an environment where we have a small number of VLANs assigned for use by our cloud environment. Our typical KVM host configuration exposes these via a number of bridge devices, and when manually bringing up new guest instances using virt-install we simply assign them to the appropriate bridge device and we're good to go.

We haven't yet figure out how to integrate Quantum into this environment (or if it's even possible). As a fallback we can use some of the other networking support available in OpenStack, but we're having a hard time determining if our problems with Quantum are simply design decisions in the code or problems in our reading of the documentation.

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I'm the PTL for Quantum :)

At this point, what you're trying to do is not supported. The initial version of Quantum is focused on a model where there is a pool of VLANs (or equivalent) that can be allocated to a logical network based solely on the discretion of Quantum. Outside of manipulating the database directly, you can choose to map a quantum network to a specific VLAN.

The good news though is that people are working on enabling this via the API (and thus, CLI) for a release in mid-july:

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Thanks for the answer. I'm still not sure I completely understand the network model that Quantum offers, but part of the problem is that I've had a hard time finding good architectural documentation about how all the parts fit together. If there is such a document out there, it would be great if you could add the link to your answer. The blueprint you've linked to looks promising; we'll definitely keep our eyes on it. – larsks May 25 '12 at 0:21
Thank you for popping in and giving us an official answer! – Magellan May 25 '12 at 17:22

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