Proposed by Özgür Akgün
This is the simple version of the transshipment problem. It is a network flow problem with three kinds of nodes: warehouses, transshipment points and customers. Warehouses act like source nodes and customers act like sink nodes. Products are to be transferred from warehouses to customers via transshipment points. In more complex real-life applications of this problem transshipment points provide a possibility for extra handling (packaging, splitting, consolidating) and/or change of transportation mode. See the Wikipedia article for some variations.
The problem can be used as a benchmark as either an optimisation problem (minimising total cost) or as a satisfaction problem (with a given upper bound for total cost).
See Warehouse Location Problem for a related problem.