Research on algorithm for physical topology discovery in heterogeneous multi-subnet

Knowledge of the physical topology of an IP network is crucial to a number of network management tasks, including reactive and proactive resource management, root-cause analysis, and event correlation. Given the dynamic nature of IP networks, keeping track of network topology information manually is a daunting task. So, effective algorithms for automatically discovering physical topology of an IP network are necessary. Earlier topology discovery has mainly concentrated on discovering logical (i.e., layer-3) network topology, which implies that the connectivity of all layer-2 elements in networks is ignored. In this paper, we present a novel algorithm for discovering physical (i.e., layer-2) topology in heterogeneous (i.e., multi-vendor) multi-subnet. The algorithm presented in this paper relies on standard SNMP MIB information that is supported by IP network elements and require no modification to the operating system software. The algorithm has been implemented and has been tested on our own research network. The experimental results can clearly validate our approach, demonstrating that our tool can consistently discover the accurate physical topology in time.