In a context of profound transformation of the relations between firms, an organizational paradigm is developing rapidly: the network. Networks of firms are specific co-ordination modes between market and hierarchy, and need collaborative tools to regulate their activities fairly and to limit opportunism. This paper exposes a method to calculate satisfying routes for customers' orders within manufacturing networks of SMEs. This method aims at designing the routing of activities, so as to meet the customers' needs in terms of cost, quality and delivery time (short-term performance constraints), and to promote learning processes and skills exchanges within the network (long-term performance criteria). The method is illustrated with a case study.