【作者】 珠杰；

【导师】 孙学军；

【作者基本信息】 天津大学 ， 计算机应用技术， 2005， 硕士

【摘要】 随着IPv6网络的发展,分布在IPv4互联网角落中的IPv6站点有访问IPv6主干网的需求。为此,IETF的工作组NGTRANS讨论了许多过渡技术,从总体上分为双栈技术、隧道技术、协议翻译技术。本文具体讨论了隧道技术中的一种——6to4隧道技术以及由此产生的6to4路由器、6to4中继路由器,并重点讨论了6to4路由域中存在的非对称路径问题。非对称路径是指从某一路由器出口离开的分组不能通过同一路由器返回。由6to4路由器和6to4中继路由器组成的6to4路由域中,经常出现来回分组不能经过同一个6to4中继路由器的情况,由此在6to4路由域中形成非对称路径问题。在6to4路由域中讨论非对称路径问题有以下几点原因:一是6to4中继路由器分散在世界的各个地方,密集程度不高。当6to4路由器和6to4中继路由器之间相距很远时,非对称路径上来回分组的时延有很大的差别,网络传输性能上造成了一定的影响,特别是时延比较敏感的业务(IP Phone等)更受影响。二是非对称路径给6to4路由器带来安全问题,容易遭到恶意用户的拒绝服务攻击。为解决上述的问题,本文通过路由策略和策略路由的方法对非对称路径进行了控制。在路由策略解决方案中从网络拓扑结构、路由宣告、BGP4属性设置来控制非对称路径,这是一种整体上控制路径的方法。在策略路由方案中利用路由映射表,通过源IP地址/目的IP地址来进行路由选择,从而达到控制路径的目的。通过仿真结果初步证实,通过路由策略和策略路由消除非对称路径,网络的传输性能上有明显的提高。更多还原

【Abstract】 With the development of IPv6 network, IPv6 sites in the corner of the IPv4 Internethave demand to visit IPv6 backbone. Therefore, IETF NGTRANS workgroup discussmore transition technology, there are dual stack, tunnel and protocol translation. Alongwith one of tunnel,6to4 Tunnel ,We discuss 6to4 Router and 6to4 Relay Router and discussa problem of asymmetric paths in the 6to4 routing domain emphatically.Asymmetric path is a traffic depart from a router interface, but return the differentrouter. The 6to4 routing domain includes 6to4 router and 6to4 relay router. in the 6to4communication, the traffic may be the different paths in the both direction, we call theasymmetric paths in the 6to4 routing domain.There are a few reasons that discuss problem of asymmetric paths. First of all, the6to4 relay router spread around Internet dispersible. Forwarding and backing packets havedifferent delay as increasing distance of 6to4 router and 6to4 relay router. Thus transmitperformance gets influence like IP Phone traffic. Secondly 6to4 router suffer from attackDenial of Service easily, because there are security problem of asymmetric paths in the6to4 routing domain.In order to solve these problems at one time, we propose routing policy and policybased routing schemes to control the asymmetric paths. The routing policy scheme avoidinfluences of asymmetric path via change topology, announce routing and setting BGP4attribute. This is a scheme of control paths from macrocosm. In order to control the paths,the policy based routing scheme choose route via source address/destination address anduse mapping table. Simulation results confirm that applying these schemes in 6to4 routingdomain improves average throughout.更多还原