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

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.