QOS aggregation algorithms in hierarchical ATM networks

We propose a new private network-to-network interface (PNNI) aggregation algorithms for hierarchical ATM networks. Standard PNNI routing provides a scalable hierarchical routing capability to support a large ATM network, and its hierarchy mechanism can decrease the network complexity significantly. However, in order to support effective QoS-based routing across foreign subnetworks, the topology aggregation mechanism, representing the lower level network topology to higher level, becomes a key issue. PNNI specification defines general notions of this aggregation mechanism, leaving enough opportunities for subnetwork administrators to choose the amount of aggregated information that they advertise. So far, no feasible PNNI compliant algorithms have been proposed. We propose a new three step aggregation scheme to solve the problem. We evaluated the proposed scheme, based on large-scale simulations with different network topologies, traffic scenarios, and performance metrics. The proposed scheme delivers good network performance while significantly reducing the network complexity