Efficient hierarchical QoS routing in ATM networks

For reducing network information to achieve scalability in large ATM networ ks, ATM Private Network-to-Network Interface (PNNI) adopts hierarchical rou ting. Consequently, although routing complexity is significantly reduced, n umerous issues in PNNI routing require further study to achieve more effici ent, accurate, scalable, and QoS-aware routing. Several methods are adopted herein to achieve efficient, scalable, and QoS- aware ATM PNNI routing, First, an efficient aggregation scheme, referred to as Asymmetric Simple, is proposed. The aggregated routing information incl udes available bandwidth, delay and cost. Second, two approaches for defini ng link costs are investigated, namely, the Markov Decision Process (MDP) a pproach and the Competitive On-Line (COL) routing approach and these are co mpared with the Widest Path (WP) approach. Finally, a dynamic update policy , referred to as the dynamic cost-based update (DCU) policy, is proposed to improve the accuracy of the aggregated information and the performance of hierarchical routing, while decreasing the frequency of re-aggregation and information distribution. Simulation results demonstrate that the proposed Asymmetric Simple aggregat ion scheme yields very good network utilization while significantly reducin g the amount of advertised information. Between these two link cost functio ns, the MDP approach provides a systematic method of defining call admissio n function and yields better network utilization than the COL approach. The proposed DCU policy also yields an enhanced network utilization while sign ificantly reducing the frequency of re-aggregation and the amount of distri buted aggregation information. (C) 2001 Elsevier Science B.V. All rights re served.