1. A method comprising: obtaining, at a network controller, network flow information from a plurality of devices in a network, wherein the network flow information from a respective device of the plurality of devices corresponds to one or more data flows that traverse the respective device; producing a plurality of network flow sub-files according to one or more specified network flow characteristics that characterize a first keyspace using the network flow information, wherein the one or more specified network flow characteristics satisfy one or more performance criteria; generating a plurality of inter-autonomous system (inter-AS) traffic sub-files by converting the plurality of network flow sub-files to a second keyspace distinct from the first keyspace, wherein each of the plurality of inter-AS traffic sub-files includes one or more inter-AS flows that characterize data traffic between at least two external AS's that traverses the network; and generating an inter-AS traffic file based on the plurality of inter AS-traffic sub-files in order to monitor traffic traversing the network.