基于地址转发表的链路层拓扑发现算法的研究与实现

发布时间：2019-07-05 20:15

【摘要】：完整准确的网络拓扑是网络管理的基础,链路层拓扑作为全网拓扑的重要组成部分,由于链路层设备的多样性、透明性以及多子网结构的复杂性,使得链路层拓扑自动发现算法成为全网拓扑发现研究的重点和难点。本文拟通过对当前主流算法和典型拓扑的分析,提出一种改进的链路层拓扑发现算法。本文首先分析了基于私有协议、基于生成树协议、基于探测包和基于地址转发表的四类链路层拓扑发现方法,发现基于地址转发表的算法具有更好的普适性。经理论分析和实际环境验证,在大规模交换网络中获得下行链路完整地址转发表与获得完整(上下行链路完整)地址转发表相比,可行性更高。因此,本研究在下行链路地址转发表完整这一前提下,对Yigal Bejerano的算法进行改进,提出一种基于最短路径的链路层拓扑发现算法。算法先利用该转发表针对每个子网构建交换设备间的最短路径,再通过分析总结出的四项端口邻接判定规则优化最短路径,使每条最短路径形成单一端口组成的序列,从而计算出网络拓扑。与当前主要文献提出的算法相比,该算法能较好的适用于多子网复杂拓扑环境,在一定程度上降低了算法复杂度。本算法采用VC++语言基于SNMP协议实现,并在某大学校园网中进行测试,能准确地发现多子网链路层网络拓扑。经理论和实际环境验证,证明本研究提出的基于下行链路完整地址转发表构建最短路径的链路层拓扑发现算法可以较好地发现复杂多子网的链路层拓扑结构,具有较强的实践意义和推广价值。
[Abstract]:Complete and accurate network topology is the basis of network management. Link layer topology, as an important part of the whole network topology, because of the diversity and transparency of link layer equipment and the complexity of multi-subnet structure, the automatic discovery algorithm of link layer topology has become the focus and difficulty of the whole network topology discovery research. In this paper, an improved link layer topology discovery algorithm is proposed by analyzing the current mainstream algorithms and typical topologies. In this paper, four kinds of link layer topology discovery methods based on private protocol, spanning tree protocol, detection packet and address forwarding table are analyzed, and it is found that the algorithm based on address forwarding table has better universality. Through theoretical analysis and practical environment verification, it is more feasible to obtain the complete downlink address forwarding table in the large-scale switching network than to obtain the complete (downlink complete) address forwarding table. Therefore, on the premise of complete downlink address forwarding table, this paper improves the Yigal Bejerano algorithm and proposes a link layer topology discovery algorithm based on the shortest path. The algorithm first uses the forwarding table to construct the shortest path between switching devices for each subnet, and then optimizes the shortest path through the analysis and summary of the four port adjoining decision rules, so that each shortest path forms a sequence composed of a single port, and then the network topology is calculated. Compared with the algorithms proposed in the current literature, this algorithm is better suitable for multi-subnet complex topology environment and reduces the complexity of the algorithm to a certain extent. The algorithm is implemented by VC language based on SNMP protocol and tested in the campus network of a university, which can accurately find the network topology of multi-subnet link layer. Through the verification of theory and practical environment, it is proved that the link layer topology discovery algorithm based on downlink complete address forwarding table can find the link layer topology of complex multi-subnet well, which has strong practical significance and popularization value.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.02

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