Optimal per - Node Rate Allocation to provide per - Flow End - to - End

In this paper, we investigate the problem of providing worst-case end-to-end delay guarantee to a leaky-bucket constrained ow traversing a series of N packet schedulers. We consider a network of routers that support the Guaranteed (G) Service class of the IETF Integrated Services (IntServ) Working Group; this service class is proposed to provide Quality of Service (QoS) in the Internet. Under this framework, a worst-case end-to-end delay bound to a ow is provided by allocating a rate at each network element on the path of the ow. We associate a cost with allocating a rate at each link. The cost is assumed to be a convex and non-decreasing function of rate. We investigate the problem of obtaining an optimal rate allocation for a ow that minimizes the overall cost subject to the delay requirement and the available link capacity constraints. Allocating an identical rate at each link on the path of a ow is a widely used approach under the Guaranteed Service framework. We investigate the optimality of this approach and show that under certain conditions, it need not be optimal. Moreover, we investigate the optimal solution to the overall cost minimization problem and give scenarios in which we can explicitly obtain the optimal solution. Based on these results, we present an algorithm for optimal rate allocation.