Data Path Rib Topology

Constraint-based routing gradually becomes an essential enabling mechanism for a variety of emerging network services such as virtual private networking and QoS support. A number of recent works have recognized its signiicance and investigated many aspects of the operation of constraint based routing and in particular its variant that is concerned with determining paths for requests with speciic QoS requirements, known as QoS routing. In this work we build on previous results on the cost of QoS routing and investigate the performance/cost trade-oos involved in the operation of a representative QoS routing architecture, elaborate on the constituents of this cost, and identify the main methods for containing the cost that QoS routing incurs on routers. Our results show that the cost of QoS routing is not excessive and that there indeed exist operational conngurations, that can achieve reasonable performance gains with only a minimal increase in processing cost when compared to conventional best-eeort routing.