Analysis of the performance of a hierarchical PNNI network

In this paper, we analyze the trade-off between performance and scalability in PNNI-driven ATM networks. The PNNI protocol, defined by the ATM Forum, provides scalable, dynamic and QoS-sensitive routing capabilities. However, the design and dimensioning of networks running PNNI is still an open question. For instance, the performance and scalability of PNNI are both affected by the routing aggregation scheme and by the link-state update frequency. However, very little is still known on how these phenomena impact the network performance (e.g., call blocking rate) or scalability (with respect to routing overhead). A model, based on random geometry, is proposed in order to evaluate analytically the impact of stale or aggregated routing information on the probability of blocking at call arrivals. Closed form expressions for both the probability of call rejection or of call crankback are obtained.