to BGP's lack of a mechanism to directly optimize for latency, rather than to selfish routing policies. It was also suggested that, were an appropriate mechanism in place, ISPs would be willing to cooperate to reduce latency rather than use hot-potato routing. Such a mechanism was later published by the same authors, first for the case of two ISPs and then for the global case. Route analytics As the Internet and IP networks have become mission critical business tools, there has been increased interest in techniques and methods to monitor the routing posture of networks. Incorrect routing or routing issues cause undesirable performance degradation, flapping or downtime. Monitoring routing in a network is achieved using route analytics tools and techniques. Centralized routing In networks where a logically centralized control is available over the forwarding state, for example, using software-defined networking, routing techniques can be used that aim to optimize global and network-wide performance metrics. This has been used by large internet companies that operate many data centers in different geographical locations attached using private optical links, examples of which include Microsoft's Global WAN, Facebook's Express Backbone, and Google's B4. Global performance metrics to optimize include maximizing network utilization, minimizing traffic flow completion times, maximizing the traffic delivered prior to specific deadlines and reducing the completion times of flows. Work on the later over private WAN discusses modeling routing as a graph optimization problem by pushing all the queuing to the end-points. The authors also propose a heuristic to solve the problem efficiently while sacrificing negligible performance. See also Collective routing Deflection routing Edge disjoint shortest pair algorithm Flood search routing Fuzzy routing Geographic routing Heuristic routing Path computation element (PCE) Policy-based routing Wormhole routing Small-world routing Turn restriction routing References Further reading Ciscopress Ciscopress External links Count-To-Infinity Problem , ways of avoiding the count-to-infinity problem Cisco IT Case Studies about Routing and Switching Internet architecture