Hop-by-Hop Routing Algorithms For Premium-class Traffic in DiffServ Networks

Bear the provision of Quality of Service (QoS) in the Internet, Differentiated Service (DiffServ) model has been proposed as a cost-effective solution. Traffic is classified into several service classes with different priorities. The premium class traffic has the highest one. The routing algorithm used by the premium class service has significant effects not only on its own traffic, but on all other classes of traffic as well. The shortest hopcount routing scheme used in current Internet turns out to be no longer sufficient in DiffServ networks. Based on the hop-by-hop routing mechanism, an interesting problem is how to find an optimal routing algorithm for premium class traffic such that (1) it works correctly and efficiently for premium traffic; and meanwhile (2) it reduces negative influences to other classes of traffic (such as bandwidth starvation, excessive delay jitter, etc.). We call this problem the Optimal Premium-class Routing (OPR) problem which is NP-Complete. To handle the OPR problem, first, we analyze the strength and weaknesses of two existing algorithms (Widest-Shortest-Path algorithm and Bandwidth-inversion Shortest-Path algorithm). Second, we apply to the OPR problem a novel heuristic algorithm, called the Enhanced Bandwidth-inversion Shortest-Path (EBSP) algorithm. We prove theoretically the correctness of the EBSP algorithm, i.e., it is a consistent and loop-free hop-by-hop routing algorithm. Our extensive simulations in different network environments show clearly that the EBSP algorithm performs better in complex, heterogeneous networks than the other two hop-by-hop routing algorithms for the premium class traffic.