Our motivation is to design a traffic model for uncongested IP backbone links that is simple enough to be used in network operation, and that is protocol and application agnostic in order to be as general as possible. The proposed solution is to model the traffic at the flow level by a Poisson shot-noise process. A flow is characterized by its arrival time, its size, its duration, and its rate function (i.e., shot). We validate the model by simulation and we analyze its accuracy with real backbone traffic traces. Despite its simplicity, our model provides a good approximation of the real traffic observed in the backbone and of its variation. We also explain how our model can be specified to the case of TCP flows. To this end, we present a model for TCP shot that only uses the size of the flow and its duration. This latter model is independent of the round-trip time and the packet loss rate.