Constella: Autonomous IP Network Topology Discovery of Large, Multi-subnet and Dynamic Networks

Abstract

Information and communication are two of the most important strategic issues for the success of every enterprise. While today nearly every organization uses a substantial number of computers and communication tools (telephones, fax, and personal handheld devices), they are often still isolated. While managers today are able to use the newest applications, many departments still do not communicate and much needed information cannot be readily accessed. To overcome these obstacles in an effective usage of information technology, computer networks are necessary. Currently we see tremendous expansion in the area of network deployment. As companies realized the cost benefits and productivity gains created by network technology, they began to add networks and expand existing networks almost as rapidly as new network technologies and products are being introduced. The problems associated with network expansion affect both day-to-day network operation management and strategic network growth planning. Each new network technology requires its own set of experts. An urgent need has arisen for automated network management (including what is typically called network capacity planning) integrated across diverse environments. Network management means different things to different people. In some cases, it involves a solitary network consultant monitoring network activity with an outdated protocol analyzer. In other cases, network management involves a distributed database, auto polling of network devices, and high-end workstations generating real-time graphical views of network topology changes and traffic. In general, network management is a service that employs a variety of tools, applications, and devices to assist human network managers in monitoring and maintaining networks. Knowledge of the up-to-date physical network topology (Layer 2 and Layer 3) is crucial among network management tasks like congestion avoidance, resource management, resource discovery, root-cause analysis and event correlation. Due to dynamic nature of today’s IP networks, keeping track of topology information manually is a daunting task. Thus efficient algorithms for automatically discovering physical network topology are necessary. Earlier work has typically concentrated on discovering topology either using completely SNMP-MIB or ICMP echo request/reply, DNS, Trace route, etc. Our proposed algorithm does not rely totally on SNMP-MIB information as it is not usually supported by all devices in the network. Instead we propose an approach where SNMP agent is enabled only on the routers and managed switches. Rest of the network computers need not have SNMP agent enabled this increases the scalability of my algorithm. The experimental results validate our approach, demonstrating that our algorithm discovers accurate physical network topology.