【作者】 臧天宁；

【导师】 王慧强；

【作者基本信息】 哈尔滨工程大学 ， 计算机应用技术， 2007， 硕士

【摘要】 BGP是目前Internet上广为采用的AS间的动态路由协议。模拟是研究BGP协议的有效手段之一。随着被模拟的网络的规模成比例的增长，路由模拟成为了一个关键的问题。对于目前BGP协议模拟效率都相对较低的问题，为了提高BGP协议模拟的性能，减少BGP模拟过程中的CPU负载消耗，本文针对网络模拟的优化问题，做了以下几个方面工作。首先对网络协议，特别是BGP协议进行了概述。然后阐述了网络模拟技术，尤其对路由模拟进行了较为深入的分析和总结。同时介绍了相关的网络模拟软件，特别是对BGP协议的专用模拟器BGP++的形成过程进行了系统的阐述。对路由模拟技术，从两个方面做了路由策略优化的工作。第一个方面是对路由查找过程的改进，优化了按需计算的NIx-Vector策略，在进行NIx-Vector计算之前先搜索当前路由器节点的相邻节点集合，如果找到了目的节点ID则直接将目的节点ID作为下一跳路由器地址返回，而不必再进行Nix-Vector向量的计算过程；另一个方面是对模拟过程的改进，首先去除BGP模拟过程中的TCP特性，用模拟器中路由节点间的连接链路代替，即去除BGP协议模拟过程中对TCP的依赖性。其次，修改了BGP协议通过KeepAlive-Notification来确定路由动态变化的方式，改变了BGP协议模拟过程中，依靠KeepAlive-Notification发现拓扑信息变化的策略。最后，在Linux系统上，以BGP++模拟器为基础，进行了真实性比较实验和模拟性能比较试验。实验结果表明，在不失真实性的前提下，这些优化技术能够有效的提高对BGP协议模拟的效率，使模拟事件数大大减少，模拟时间得到有效降低。更多还原

【Abstract】 BGP is the de facto inter-domain routing protocol of the Internet. Simulation is one of the most efficient methods for study BGP protocol. With the development of the scale of simulative network, route simulation becomes a key problem. Most of current BGP simulation has pretty low efficiency. In order to improve the efficiency of BGP simulation, this paper presents some optimization methods for reduce the CPU load. Route protocols of the Internet are firstly summarized. Border Gateway Protocol is especially explained. Technology of network simulation is narrated. At the same time, this paper introduce the software of network simulator, emphasis is BGP++, which is a simulator of BGP.In the following, some optimized methods for route simulation are presented. One is improvement for the searching process of route. Modification is made for the NIx-Vector. The neighborhood gathering of current node is looked up for destination before compute NIx-Vector. If the destination node were found, this node ID would take as the address of next hop, the process of NIx-Vector computation would not be executed. The other is betterment for process of simulation. Firstly, the characteristic of TCP is getted rid of during the BGP simulation. Relationship between BGP and TCP is removed in the simulator. Secondly, the KeepAlive-Notification mechanism of BGP is modified to decide whether a link state changes or not.At last, an experiment is designed and carried out under the Linux Operating System. The experimental results show that the efficiency of BGP simulation can be greatly improved with these optimization methods, the number of events generated during the simulation reduced largely, and the simulation time reduced greatly compared with the original BGP simulation in BGP++.更多还原