Research On The Technology Of Network Topology Discovery

In the network management system, network topology information is the foundation of other functions. It is a common issue for those network institutes to automatically discover and obtain network topology information with completeness, accuracy and efficiency. This paper focuses on the study of various network topology discovery algorithms, which are divided into two parts: network layer topology discovery and link layer topology discovery.On the study of network layer topology discovery, we introduce the current network layer topology discovery methods: algorithms base on ICMP,DNS,OSPF,SNMP. In view of the shortage of SNMP, we studied MIB, and bring up the corresponding solution. By merging IP address, introducing data structure such and limiting the scope of topology discovery, we can accurately and efficiently discover the connections between routers and subnets.The key of the link layer topology discovery in the 2nd layer is to find links between switches and switches. On the study of link layer topology discovery, we analyze the current link layer topology discovery algorithm. In order to improve the imperfect, a novel algorithm for data link layer topology discovery based on Address Forwarding Table is proposed. The form of path set is introduced into this algorithm. Based on the relatively independent characteristic of path set, it carries out the multi-threaded to be concurrent. This algorithm improves the efficiency and does not require the information of each bridge FDB table to be complete. But it can't find equipments that do not support SNMP such as dump switches. Aiming at this insufficiency, the physical topology discovery algorithm was analyzed and compared relying on standard SNMP MIB FDB and the algorithm relying on STP information in the first place. Then a new algorithm for discovering Ethernet topology was presented, which had the advantages of the two algorithms. This algorithm can find the connections between switch and switch switch and host, even though there exists switch or HUB which does not support SNMP protocol in the sub network. And then it can obtain intact and correct topology connection graph. Compared with the existing topology discovery algorithm, the algorithm which we propose has better applicability, veracity and efficiency.