oriented transport mechanism are then combined to determine the traffic necessary to cause a cost effective cutover from the routing system transport mechanism to the connection oriented transport mechanism block 625 this is done by solving the two cost functions for the traffic variable the drain rate function is then set up using the planning horizon h p and the maximum traffic function block 630 the drain rate function is also a function of time such that the drain rate function varies as time progresses specifically the drain rate will increase as time progresses through the planning window h p for example at the start of the planning window the drain rate function is low because not much time has elapsed in the planning window but as time proceeds the drain rate function increases such that at a time near the close of the planning window the drain rate function is very large this has the effect of requiring a data transport to transport large amounts of data near the end of the window to justify a cost effective cutover once the necessary functions have been established the leaky bucket 410 then begins to monitor the data flow as data arrives block 635 it is monitored by the leaky bucket 410 when data does arrive the temporary bucket contents are determined by adding the arriving data to the existing bucket contents block 640 the amount of data that has leaked from the bucket since the time that data last arrived is then determined block 645 this is done by integrating the drain rate function over the time interval for which data has arrived this yields an amount of the bucket contents which should be drained according to the drain rate function this.