[puzzle]

What kind of network policies? Millions of years ago, Google used Cariden software to simulate what happened when links went down, QoS changes were applied, etc. From what I recall, at some point, the size of the network, new special hardware and the need for more flexibility outgrew the tool's capabilities, so IIRC it was supplanted by in-house solutions that were more real-time and fit into the new SDN architecture.