Other possible components of the utility function include a prediction on the reliability of forwarding nodes and the projected remaining duration of a subscription. Furthermore, queuing delays could be modeled more explicitly than only by the bandwidth utilization [9]. We assume that for each factor there is a cost function c_f . Optional weights w_f allow trading cost factors for each other. The total cost for a given
configuration r is calculated as c(r)∶= ∑f∈Ϝ wf* cf (r). The utility is simply defined as the negative cost function ; a negative utility value has no effect on the above algorithm.