Performance of the PNNI protocol in large networks

Supporting guaranteed services in a large network requires solutions to many difficult problems. In this paper, we focus on the problem of on-demand routing of virtual circuits with quality of service guarantees. Specifically, we investigate the performance of the ATM Private Network-Network Interface (PNNI) protocol in a large topology with structure reflecting the hierarchy and locality present in internetworks. PNNI uses several techniques to maintain scalability of the routing process; each technique has an associated penalty in performance (i.e., the ability of the protocol to find routes). The tension between scalability and performance is the subject of this paper. We examine the routing performance under a variety of aggregation and topology update conditions. The work described in this paper uses a large-scale simulator being developed as part of the Scalable Self-Organizing Simulation project.