支持动态路由的网络模拟系统设计与实现

发布时间：2018-02-02 01:24

本文关键词： 网络模拟动态路由局部路由策略拥塞预知　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：近年来互联网技术不断发展，信息化进程日益推进，互联网技术在改善人们生活方式的同时也带来了很多问题。一方面，各种网络安全问题不断涌现，信息安全事件时有发生；另一方面，网络规模和复杂性的增长对现有的协议和算法提出了更高的要求，亟需研究人员进行前瞻性的研究。由于网络模拟在研究网络行为和网络协议方面具有成本低、灵活性强、模拟规模大等优点，因此，得到了越来越广泛的应用。在真实的网络环境中，路由策略的好坏直接影响到一个网络的性能，同样，在网络模拟环境中，如何模拟数据包在真实网络环境中的转发过程将直接影响模拟的真实性和模拟效率。因此，网络模拟中路由策略的设计至关重要。基于上述背景，，本文设计并实现了支持动态路由的网络模拟系统，主要完成了如下工作：第一，研究了当前网络中广泛使用的动态路由协议，分析了各个协议的优缺点，在NS3上实现了简化的OSPF协议模型，主要包括：链路状态通告的获取，链路状态数据库的构建，路由选择算法SPF的实现，路由表的生成以及路由的更新过程。第二，由于网络信息量的不断增加，拥塞已经成为制约网络性能的主要因素，因特网中广泛使用的OSPF、RIP、IGRP等路由协议对数据包进行路由时总是选择“最优路由”进行转发，使得链路拥塞时其它空闲的链路无法得到利用，造成大量网络资源的浪费。针对这一问题，提出了一种拥塞预知队列模型，通过周期性的检测队列缓冲区占用率来判断链路的拥塞状况，当队列缓冲区占用率达到一定阈值时，则认为链路有发生拥塞的趋势。第三，针对拥塞问题，提出了一种拥塞预知路由算法CPRA，算法采用了局部路由策略的思想：当队列缓冲区占用率达到一定阈值时，通过深度优先搜索寻找另一条通往目的节点的路径，然后将数据包沿着该路径转发。在NS3上的仿真结果表明，相对于OSPF，使用CPRA能够显著提高网络的性能，其中，网络吞吐率提高了约50%，端到端平均时延减少了0.3s。
[Abstract]:In recent years, with the continuous development of Internet technology, the process of information technology is advancing day by day. Internet technology not only improves people's way of life, but also brings a lot of problems. On the one hand, a variety of network security problems continue to emerge. Information security incidents occur from time to time; On the other hand, the growth of network size and complexity puts forward higher requirements for existing protocols and algorithms. Because network simulation has the advantages of low cost, strong flexibility and large simulation scale in studying network behavior and network protocol. Has been more and more widely used. In the real network environment, the routing strategy directly affects the performance of a network, similarly, in a network simulation environment. How to simulate the forwarding process of packets in real network environment will directly affect the authenticity and efficiency of simulation. Therefore, the design of routing strategy in network simulation is very important. Based on the above background, a network simulation system supporting dynamic routing is designed and implemented in this paper. The main work is as follows: First, the dynamic routing protocols widely used in the current network are studied, the advantages and disadvantages of each protocol are analyzed, and the simplified OSPF protocol model is implemented on NS3. It mainly includes: the acquisition of link state notification, the construction of link state database, the implementation of routing algorithm SPF, the generation of routing table and the updating process of routing. Secondly, due to the increasing amount of network information, congestion has become the main factor that restricts the network performance. OSPFN RIP, which is widely used in the Internet, is widely used. IGRP and other routing protocols always select the "optimal route" to forward the packets, which makes the other idle links can not be utilized when the link is congested. In order to solve this problem, a congestion prediction queue model is proposed to determine the congestion status of the link by periodically detecting queue buffer occupancy. When queue buffer occupancy reaches a certain threshold, the link is considered to be congested. Thirdly, a congestion predictive routing algorithm, CPRA-based, is proposed, which adopts the idea of local routing strategy: when queue buffer occupancy reaches a certain threshold. Another path to the destination node is found by depth first search, and then the packet is forwarded along the path. The simulation results on NS3 show that it is relative to OSPF. The performance of the network can be significantly improved by using CPRA. The throughput of the network increases by about 50 and the average end-to-end delay decreases by 0.3 s.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.08

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