The Study On Topology Discovery Of Hierarchical Network

In this quickly developing information age, all organizations depend on computer network so much that network management has become more and more vital. Therefore, they desire more perfect network management urgently. Network topology discovery is the most fundamental function of network management. By acquiring the information of network topology, network administrator can locate network failures, discover network bottleneck and master the current status of the network. Then, the administrator can manage and optimize the network better and better. However, in the mean time, entering the network topology information manually is a tedious or impossible task for administrator, because network expanse has become larger and larger. As single-center network management does not meet the network management's requirement any more for large-sized or distributed network, it need hierarchical network management. The focus of this thesis is how to implement automatic topology discovery for hierarchical network.A hierarchical network includes multiple single interconnection networks. In order to implement hierarchical network topology discovery, we need to acquire topology information of all single networks. Network topology discovery is composed of network layer topology discovery and link layer topology discovery.In the first part of this thesis, we introduce the current network layer topology discovery methods, and improvement that achieve high efficiency and speed_based on SNMP. According to breadth-first-search traversal algorithm, we conclude the connection between router and router, router and subnet by getting the value of route MIB variables of routers. In the meantime, we use multi-thread to scan all subnets to get the information of all active devices.By study on the current link layer topology discovery algorithms and the development trend of modern switch area, we provide a method based on Spanning Tree Protocol and SNMP to discover the link layer topology. We conclude the connection among switches by getting the value of MIB variables, which are relative to Spanning Tree. And we can use the Address Forwarding Table information of the switch ports to find the connection among terminal devices and switches. The advantage of this method is that it can update topology in real time by getting the trap information from switches.We implement automatic entire single-layer network topology discovery by combining the above methods and propose a new method to implement hierarchical network topology discovery. In order to authenticate upper-layer management center and ensure the safeness and integrity of data information, we propose that topology information is exchanged between network management centers of every layer based on SSL Protocol.Finally, we draw some conclusions and outline further work.