Multi-echelon networks are networks in which troducts are located in a variety oflocations along ir path to distribution, some of which are in differ- echelons', or tiers, of the enterprise's distribution work. For example, large retailers' distribution networks often consist of a regional distribution center and a larger number of forward distribution centers. The presence of multiple echelons in a distribution network makes inventory management more difficult because each echelon is isolated from other echelons, so changes in inventory made by one echelon may have unpredictable consequences on the others.