【摘要】 流量模拟包括包层次模拟、流层次模拟和混合模拟。包层次模拟粒度小、精度高、计算量大,流层次模拟采用高层抽象以提高模拟效率,但粒度较粗,精度较差,在网络动态性大时,"连锁反应"导致模拟效率下降。混合模拟在模拟精度和模拟效率间进行折衷,一种是将需要关注的部分采用包层次模拟,其它部分采用流层次模拟,另一种是进行离散变量短时间间隔的连续化,两类方法均不能完全消除"连锁反应"的影响。提出了包层次和聚集控制的混合模拟方法,降低了"连锁反应"的影响,实现了聚集TCP流的模拟。更多还原

【Abstract】 There are three types of traffic simulation: packet-level simulation,fluid-level simulation and hybrid simulation.The characters of packet-level simulation are small simulating granularity,high accuracy and large computational requirements.With fluid-level simulation,the models with a higher level of abstraction are used to improve simulation efficiency with rather large simulating granularity,thus resulting in problems of accuracy.And further more,the ripple effect occurs with high network dynamics,which will decrease the simulation efficiency.Hybrid simulation is a tradeoff between simulation accuracy and efficiency.One type of tradeoff is combining packet-level simulation with fluid-level simulation;the other is averaging to continuously approximate discrete variables over short time intervals.With the first hybrid simulation,the packet-level simulation is used to simulate the interested part,while the fluid-level simulation for the rest part.The two types of hybrid simulations are also affected by the ripple effect.To decrease the ripple effect,a hybrid simulation method combined packet-level simulation and aggregated control is proposed to simulate the aggregated TCP flows.更多还原