Configuration at the level of the distribution system concerns primarily the problem of location of the nodes in a geographic space and distribution of capacity among the nodes. The first may be referred to as facility location (with the special case of site selection) while the latter to as capacity allocation. The problem of outsourcing typically arises at this level: the nodes of a supply chain are very rarely owned by a single enterprise. Distribution networks can be characterized by numbers of levels, namely the number of intermediary nodes between supplier and consumer: