Dynamic update of aggregated routing information for hierarchical QoS routing in ATM networks

For achieving scalable and QoS-ware in a large ATM networks, the ATM Private Network-to-Network Interface (PNNI) adopts hierarchical routing which reduces nodal and link information. In order to perform hierarchical routing efficiently, the network will consist of subnetworks, called peer groups, and peer groups will advertise the aggregated information periodically which is based on time-based update interval or on an event driven basis. The time-based update policy is not adequate to cope with dynamic network traffic. Therefore, in this paper, we propose a dynamic update policy, referred to as the cost-based update (DCU) policy, to enhance the accuracy of aggregated information and the performance of hierarchical routing, while decreasing the frequency of re-aggregation and information distribution and the overhead of communication. In our simulations, we compare the DCU policy with PNNI time-based update (PNNIU) policy, full update (FU) policy, and logarithm of residual bandwidth update (LRBU) policy. Our simulation results indicate that the proposed DCU policy yields better performance while significantly reduces the frequency of re-aggregation and the amount of distributed aggregation information.