Source-Oriented Topology Aggregation with Multiple QoS Parameters in Hierarchical ATM Networks

In this paper, we investigate the problem of topology aggregation (TA) for scalable, QoS-based routing in ATM networks. TA is the process of summarizing the topological information (QoS parameters, interconnectivity, etc.) of a given subset of network elements. This summary is then ooded throughout the network, and is used by various nodes to determine appropriate routes for ATM connection requests. While TA is needed for scalable routing, it often results in the loss of some topological details that impact the routing performance. Hence, a key issue in the design of a TA scheme is the appropriate balance between compaction and the corresponding routing performance. The contributions of this paper are twofold. First, we introduce a source-oriented approach to TA, which provides better performance than existing approaches. The intuition behind this approach is that the advertised topology-state information is used by source nodes to determine tentative routes for connection requests. Accordingly, only relevant information to source nodes needs to be advertised. We integrate the source-oriented approach into three new TA schemes that provide diierent tradeoos between compaction and accuracy. Second, we extend our source-oriented approach to multi-QoS-based TA. A key issue here is the determination of appropriate values for the multiple QoS parameters that are associated with a logical link. Two new approaches to computing these values are introduced. Extensive simulations are used to evaluate the performance of our proposed schemes.