Vendor Managed Inventory (VMI) is an inventory management system in which making decision about replenishment the customers' inventory is its supplier's duty. One of difficulties in implementing VMI is how to develop a distribution strategy which can satisfy all the customers' needs and meet the supplier's desired advantages such as decreasing the distribution costs, simultaneously. Developing such a distribution strategy is discussed in the framework of Inventory Routing Problem (IRP). Most of papers in the literature have modeled the IRP in a case that the supplier has only one distribution center. This assumption, in many cases, is contrary to the fact. In this paper, we study the situation in which a single product must be distributed from a set of distribution center to a set of customers. A fleet of homogeneous vehicles with limited capacity is available for the distribution. We solved our IRP model using a rolling horizon framework. The problem is decomposed into an inventory problem and a routing problem that are solved by a linear programming model for small size problems, and for large scale problems we developed a heuristic algorithm which we demonstrate its effectiveness in an extensive computational study.
