Efficient hierarchical QoS routing in ATM networks

✍ Scribed by Ben-Jye Chang; Ren-Hung Hwang

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 233 KB
• Volume: 24
• Category: Article
• ISSN: 0140-3664
• DOI: 10.1016/s0140-3664(01)00306-1

✦ Synopsis

For reducing network information to achieve scalability in large ATM networks, ATM Private Network-to-Network Interface (PNNI) adopts hierarchical routing. Consequently, although routing complexity is signi®cantly reduced, numerous issues in PNNI routing require further study to achieve more ef®cient, accurate, scalable, and QoS-aware routing.

Several methods are adopted herein to achieve ef®cient, scalable, and QoS-aware ATM PNNI routing. First, an ef®cient aggregation scheme, referred to as Asymmetric Simple, is proposed. The aggregated routing information includes available bandwidth, delay and cost. Second, two approaches for de®ning link costs are investigated, namely, the Markov Decision Process (MDP) approach and the Competitive On-Line (COL) routing approach, and these are compared 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 aggregation scheme yields very good network utilization while signi®cantly reducing the amount of advertised information. Between these two link cost functions, the MDP approach provides a systematic method of de®ning call admission function and yields better network utilization than the COL approach. The proposed DCU policy also yields an enhanced network utilization while signi®cantly reducing the frequency of re-aggregation and the amount of distributed aggregation information.