Before developing a solution method we first analysed the data to get a better understanding of the problem : what determines the total cost level? Which orders must be shipped directly and which orders via a DC? There is no cost difference between the various products ; the origin destination combinations and the order pattern of a certain product determine the costs needed to ship the order of that products. We can calculate in advance the cost of a certain order when it is shipped via a DC ; however we cannot calculate the cost when this order is shipped directly because this also depends on other directly shipped orders from the same PP. So we cannot compare for a certain order from the cost difference in shipping directly or via a DC. From the tariff tables it appears that direct shipping is in general cheaper than shipping via a DC.