基于网络拥塞的Internet级联故障建模

Modeling Cascading Failures for Internet Based on Congestion Effects

Internet是一个典型的具有自组织临界特性的复杂网络,分析了Internet级联动力学特点,指出了两点可能引发级联故障的原因;不同于以往的介数模型,提出了节点拥塞函数,相当于给每个节点赋一个动态的权值,以表征该节点的拥塞程度;加入了延迟时间,在永久删除策略和不删除策略之间建立关联.另外,建立了新的网络效率评估函数并以此衡量级联故障的严重性.仿真实验研究了不同的拓扑结构、规模、延迟时间、节点处理能力和包产生速率对拥塞传播的影响,揭示出级联故障传播分为3个阶段以及影响传播的主要因素.

Internet is a complex network with the characteristics of self-organized criticality If the nodes with many more connections are attacked,it may lead to dropped efficiency and even abnormal due to overload The successive traffic on the overloaded nodes is compelled to reroute to avoid the congested nodes The bypassing may congest other downstream nodes and lead to more traffic detour and node congestion,and then a cascading failure may happen The cascading dynamics of the Internet are analyzed and two reasons are pointed out which may cause cascading failures Different from betweenness centrality,the congestion function to represent the congested extent of node is proposed By introducing the concept of ＂delay time＂,the correlation between permanent removal and non-removal is built,and the flexibility of model is improved And a new assessing function of network efficiency based on congestion effects is given in order to measure the destruction of cascading failures,which highlights a more meaningful way to measure the damage of cascading failures Moreover,some impacts of structure and size of topology,delay time,handling capability and generating speed of packets on congestion propagation are also investigated,and congestion propagation process consisting of three phases and some factors affecting transition phenomenon are uncovered