spirent-思博伦-Test-centerTesting.pptx

Click to edit Master text styles,Second level,Third level,Fourth level,Click to edit Master title style,#,PROPRIETARY AND CONFIDENTIAL,HOME,How to measure the SLA over a Microburst with Spirent TestCenter,Testing the Microburst,传,统意义上的,Burst,传统意义上的,Burst,是测试流随时间采用统一的方式变化,.,这种统一的变化方式通常是方波的方式，由以下几个参数定义：,峰值速率,(,通常是,100,线速,),一个,Burst,内帧的数目,(Burst Size),IBG(Interburst Gap),Burst cycle count,传,统意义上的,Burst,，通常测试队列和缓冲的深度,Time,Rate,The Problem,现实世界的流量不是简单传统意义上的,Burst,因为传统意义上的,Burst,有下列缺乏现实意义的特征,:,统,一分布,均匀地址密度,可预测,被测设备真实工作特征,:,需要把新的地址加入,FIB,数据库，这些新地址出现的速率是瞬时变化的,当新的流量对系统产生压力时候，维护流量的完整性,根,据不同的参数保证,SLA,(DiffServ,VLAN PRI,etc),能够处理瞬时的，完全不相同，不可重复的流量变化。,传统,Burst,不能完全测试真实世界的流量模型,解,决之道：采用,Microburst.,什么是,Microburst,“In real-world traffic conditions,with differentiated traffic under SLA mandates(The Service Flow),a microburst is a pseudo-random,multi vector expansion and contraction within very short periods of time.Typically,variability happens by rate,unlearned address density,period density.For a Device Under Test(DUT)to successfully manage the microburst,the service flow SLA must be maintained.”,Model for Microburst,A traffic microburst is a traffic condition that simultaneously expands instantaneous rate,layer 2 address density,layer 3 address density,QoS Codepoint density within sudden pseudo random scale capped by the physical medium limits(such as maximum packets per second).To variablized a microburst,we must define variables.The first variable is delta(=2 mSec is typical)is the time window of change.This is the measurement window where metrics are dynamically expanding.Next,beta and beta represent the address density within a delta window(=10 Random,unique MAC+IP addresses per delta,pre burst is typical)and(is the address density per delta within the burst).Each burst will use a gamma statistical distribution as a weighting factor:,X represents maximum PPS of the medium,and are provided parameters to skew the shape.Finally,there is a simple uniform random distribution,that will pick the number of bursting windows of deltas.,Thus,a rate over burst of a microburst may be modeled as:,Also,the Max rate may not be larger than the natural medium.Address need to be truly random(Like RFC-4814,to prevent summarization),简,单解释,Microburst,“,It is a traffic pattern thats like a spike except microbursts are short in time,such as 100,microseconds”-,Pramod Srivatsa,manager,server access virtualization at,Cisco,Microburst,是类似尖刺的流量模型，,Microburst,持续的时间很短，比如,100,微秒或以下。,Microburst,具有随机性,Microburst,可表现在流量，地址学习，,burst,时间,典,型案例,Microburst,的影响,银行或者证券交易所,业,务特征,一次交易,(,如股票竞价，银行交易等,),的数据量不大,交易频率高，同时有大量交易发生,对网络架构或者网络中的交换机，很容易产生,Microburst,不能正确处理,Microburst,的影响,数据丢失竞价失败或者交易失败,时,延过大交易延误，交易阻塞,应,用失步，影响一系列决策行为,Spirent Testcenter Manual-based Schedule:Microburst,实现,Spirent Testcenter Manual-based Schedule,示例,在千兆口上设置的如下图所示,Manual Schedule,序列,发包次序,:,A.,第,一,条测试流,（,High Priority-Stedy State-AF31,）,发送,1,个,burst,，含,10,个包，,burst,内,10,个包的发送速率是,10,线速,(100Mbps),B.12ns,以后，第,一条测试流（,High Priority-Stedy State-AF31,）再发送一个,burst,，含,10,个包，,burst,内,10,个包的发送速,率是,10,线速,(100Mbps,),Spirent Testcenter Manual-based Schedule,示例,(,二,),发包次序,(,续上页胶片,):,C.12 ns,以后，第二条测试流（,Nominal-Best Effort-Delta 1,）发送,3,个,burst,，每个,burst,含,19,个包，,burst,内,19,个包的发送速率是,100,线速,(1000Mbps),，,Burst,之间的间隔是,1344ns,D.12ns,以后，第三条,测试流,（,Nominal-Best Effort-Delta 2,）发送,5,个,burst,，每个,burst,含,22,个包，,burst,内,22,个,包的发送速,率是,9,0,线速,(900Mbps),，,Burst,之间的间隔是,323ns,Spirent Testcenter Manual-based Schedule,示例,(,三,),发包次序,(,续上页胶片,):,E.12 ns,以后，第四条测试流（,Nominal-Best Effort-Delta 3,）发送,7,个,burst,，每个,burst,含,34,个包，,burst,内,34,个包的发送速率是,8,0,线速,(800Mbps),，,Burst,之间的间隔是,12ns,F.12 ns,以后，第三条,测试流,（,Nominal-Best Effort-Delta 2,）发送,19,个,burst,，每个,burst,含,56,个包，,burst,内,56,个,包的发送速,率是,70,线速,(700Mbps),，,Burst,之间的间隔是,167ns,Spirent Testcenter Manual-based Schedule,示例,(,四,),发包次序,(,续上页胶片,):,G,.12 ns,以后，第,五,条测试流（,Nominal-Best Effort-Delta,4,）发送,34,个,burst,，每个,burst,含,3,个包，,burst,内,3,个包的发送速率是,60,线速,(600Mbps),，,Burst,之间的间隔是,234ns,H,.12 ns,以后，第,二,条,测试流,（,Nominal-Best Effort-Delta 1,）发送,12,个,burst,，每个,burst,含,77,个包，,burst,内,77,个,包的发送速,率是,55,线速,(550Mbps),，,Burst,之间的间隔是,123ns,Spirent Testcenter Manual-based Schedule,示例,(,五,),发包次序,(,续上页胶片,):,I.12 ns,以后，第四条测试流（,Nominal-Best Effort-Delta 3,）发送,12,个,burst,，每个,burst,含,7,个包，,burst,内,7,个包的发送速率是,24,线速,(240Mbps),，,Burst,之间的间隔是,13ns,J,.12 ns,以后，重复步骤,D-J,重复,2,次,K.12ns,以后,第三条测试流,（,Nominal-Best Effort-Delta,2,）发送,346,个,burst,，每个,burst,含,3,个包，,burst,内,3,个包的发送速率是,24,线,速,(240Mbps),Burst,之间的间隔是,145ns,Spirent Testcenter Manual-based Schedule,示例,(,六,),发包次序,(,续上页胶片,):,L,.12 ns,以后，第五条测试流（,Nominal-Best Effort-Delta,4,）发送,3,个,burst,，每个,burst,含,90,个包，,burst,内,90,个包的发送速率是,72,线速,(720Mbps),，,Burst,之间的间隔是,12ns,M.12 ns,以后，第六条,测试流（,Nominal-Best Effort-Delta,5,）,发,送,99,个,burst,，每个,burst,含,2,个,包，,burst,内,2,个,包的发送速率,是,1,线速,(,1,0Mbps,),，,Burst,之间的间隔是,14ns,N,.12ns,以后，重复步骤,C,到,N,，重复,3,次,Spirent Testcenter Manual-based Schedule,示例,(,七,),发包次序,(,续上页胶片,):,O.12 ns,以后，第五条测试流（,Nominal-Best Effort-Delta,4,）发送,43,个,burst,，每个,burst,含,4,个包，,burst,内,4,个包的发送速率是,99,线速,(990Mbps),，,Burst,之间的间隔是,12ns,P.12 ns,以后，第一条,测试流,（,High Priority-Stedy State-AF31,）,发,送,1,个,burst,，,burst,内含,10,个,包，,burst,内,1,0,个,包的发送速率,是,10,线速,(100Mbps),Q,.12ns,以后，重复步骤,A,到,Q,，重复,40,次,Spirent Testcenter Manual-based Schedule,作用总结,构造任意发包次序,构,造,Microburst,谢 谢,