【作者】 李琳；

【导师】 李杰；

【作者基本信息】 中南大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 在网络管理中,网络拓扑信息是其它所有管理功能的基础。如何高完备性、高准确性、高效率地快速自动发现并获取网络拓扑信息是当今各网络研究机构共同关注的问题。本论文重点从网络层拓扑发现和数据链路层拓扑发现两级进行研究。关于网络层拓扑发现的工作,首先通过分析现有的基于ICMP、DNS、OSPF、SNMP的算法,总结了各自的优缺点和适用范围。然后通过深入学习MIB,对传统SNMP算法的不足提出了改进。通过合并路由器的多个IP地址,引入哈希链表数据结构,限制拓扑发现的范围,从而准确并高效地发现网络中的主干拓扑结构。链路层拓扑发现中的关键是发现交换机到交换机之间的连接关系。在对链路层进行拓扑发现的研究工作中,先是通过研究现有的链路层拓扑发现算法,引入了路径集合的形式,利用各路径集合相对独立的特点执行多线程并发,进而提出了一种基于路径集合的AFT链路层拓扑发现改进算法。该算法大大提高了拓扑发现的效率,并且不要求各个网桥FDB表的信息是完备的,但不能处理不支持生成树协议交换机的连接。针对这个不足,通过结合基于网桥转发表和基于网桥生成树两种算法的优点,提出了一种新的链路层拓扑发现算法。在网络中存在不可网管交换机或HUB的情况下该算法都能很好的发现子网中交换机与交换机、交换机与主机之间的连接关系,得到完整、正确的拓扑连接图,较之已有的拓扑发现算法具有更好的适用性、准确性和效率。更多还原

【Abstract】 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.更多还原