Several studies of Internet traffic have shown that it is a small percentage of the flows that dominate the traffic. This is often referred to as the mice and elephants phenomenon. It has been proposed that this might be one of very few invariants of Internet traffic and that this property could somehow be used for traffic engineering purposes. The idea being that one in a scalable way could control a major part of the traffic by only keeping track of a small number of flows. But for this the large flows must also be stable in the meaning that they should be among the largest flows during long periods of time. In this work we analyse packet traces of Internet traffic and study the temporal characteristics of large aggregated traffic flows defined by destination address prefixes.