Distribution Resource Planning (DRP) 
Purpose
The objectives of Distribution Resource Planning (DRP) in the SAP System are:
During the net requirements calculation the system compares the available stock and the planned receipts from the source of supply with the planned independent requirements and the incoming sales orders. If there is a material shortage (available stock is less than the quantity required), the system creates an order proposal.
The DRP process can be used for the entire supply chain including the production plants. DRP includes the production and purchasing in the planning process for the production plant.
Prerequisites
In order to perform a DRP run, you must:
Process flow
Schedule the DRP runs for your network as you would a planning run.
Result