We introduce a six layer model of traffic variations and a corresponding model of management actions. In particular, we traffic study real time traffic management on the traffic and session levels which correspond to variations on the hour and minute levels. Using virtual paths (VPs) and virtual channels (VCs) as the managed entities on the two levels respectively, we put forward a simple and robust strategy for traffic management in real time: For slow variations, i.e. on the traffic level, all nodes simultaneously monitor offered traffics and forward the result to a network management centre (NMC); The NMC computes a new set of optimal VPs compares the result to the existing network; If a change appears profitable, the necessary information is sent back to the nodes and the new design is implemented. For fast variations, i.e. on the session level, dynamic routing schemes similar to those of public switched telephone networks are employed. Applying our strategy to control general networks subject to traffics which in advance are known only as expectations, we develop simple methods for traffic observation, derive the optimal observation interval, brie y review algorithms to compute VP networks, develop a cost optimal test to determine whether to implement a new design or not, and derive the optimal updating interval. Running our strategy in a simulator, we discover a considerable adaptivity and a performance far better than obtained by alternative methods.