Real-time Network Monitoring Supporting Percentile Error Objectives
A. Prieto, Rolf Stadler · 2007
Abstract. We report on the versatility of A-GAP for supporting different types of accuracy objectives. Previously, we considered accuracy objectives expressed in terms of the average error. In this paper, we focus on percentile error objectives. A-GAP is a protocol for continuous monitoring of network state variables. Network state variables are computed from device counters using aggregation functions, such as SUM, AVERAGE and MAX. A-GAP is designed to achieve a given monitoring accuracy with minimal overhead. A-GAP is decentralized and asynchronous to achieve robustness and scalability. It executes on an overlay that interconnects management processes on the devices. On this overlay, the protocol maintains a spanning tree and updates the network state variables through incremental aggregation. Based on a stochastic model, it dynamically configures local filters that control whether an update is sent towards the root of the tree. We evaluate A-GAP through simulation using real traces for an ISP topology (Abovenet). The results prove the versatility of A-GAP for supporting different types of accuracy objectives. The results also show that we can effectively control the trade-off between accuracy and protocol overhead, and that the overhead can be reduced significantly by allowing small errors.