The Research And Application Of LAN Topology Discovery

With the exploding scale and complexity of Internet in these years, the demand of Network Management System becomes more urgent. The correct and advanced network topology information can provide the holistic network structure and state to network managers effectively. It is a common issue for those network institutes to automatically discover and obtain network topology information with completeness, accuracy and efficiency. Now, the research on network topology discovery technique is focused on network layer mainly, and the discovery technique is still immature and nonsystematic, so much more attention should be paid urgently to the issue. In addition, the study is transferred from network layer to data link layer. The link layer topology discovery can discover the physical topology internal a LAN, which the network layer topology discovery can not discover.As one of the most important tasks, this paper is from Science and Technology Plan Project of Guangdong Province "Involving secret information security monitoring system and key technology research and development". New ideas and methods have been given and large amount of materials and certain improvement has been obtained on this project.Based on the analysis of the existing automatic topology discovery techniques, this paper presents a new topology discovery algorithm for heterogeneous TCP/IP networks using standard SNMP MIBs. For the network layer logical network topology discovery, Our algorithm makes use of the topology configuration information in routers, switches and hosts under the situation that do not generate traffic in the network in advance, to determine the interconnection between directly connected peers in a network. For the data link layer physical network topology discovery, proposed an improved algorithm based on spanning tree protocol, through the SNMP request, access to each spanning tree information saved in the switch, use the data to find a simple comparison operation, the switch can accurately determine the connection between the relationship to derive the Ethernet physical network topology. Finally, to determine the IP level and link-level topology map. Under the premise that the key network equipment favor SNMP, the algorithm used by this text has a better stability and operates in brief, obtain more accurate network topology, with strong operational line.A new visualization method, which applies to the display of the topology based on hierarchical structure, was proposed. It visualized the topology based on hierarchical structure with the major devices being separated from the minor devices in the different hierarchy. The major devices were hierarchically displayed on screen from top to bottom. The basic concept and important techniques in implementing the method were presented.