Comment 1 for bug 1090447

Controllers need 2 interfaces for our networking model to function properly. One interface is used for API/GRE endpoints and the other is configured for bridging and is used by Quantum/OVS for VM external connectivity. See this commit for details:

https://github.com/danehans/folsom-manifests/commit/f82ebc46fe993453151c07a268cddbae4019a8a5#commitcomment-2320125