This Recommendation provides guidelines for the design of routing methods within TDM-, ATM-, and IP-based networks, and makes particular recommendations on bandwidth reservation, route selection, and QoS routing. It recommends these guidelines based on established practice, particularly as applied within TDM-based PSTN networks, and addresses the cases when PSTN's evolve to incorporate IP- or ATM-based technology. Guidelines on routing methods are covered in clause 5, and examples are given in clause 6 for the use of the routing methods.