Generate Possion Dis. step1:Generate a random number between [0,1] step2:Let u=F(x)=1-[(1/e)x] step3:Slove x=1/F(u) step4:Repeat Step1~Step3 by using different u,you can get x1,x2,x3,...,xn step5:If the first packet was generated at time [0], than the second packet will be generated at time [0+x1],The third packet will be generated at time [0+x1+x2], and so on …. Random-number generation 1.static method random from class Math -Returns doubles in the range 0.0 <= x < 1.0 2.class Random from package java.util -Can produce pseudorandom boolean, byte, float, double, int, long and Gaussian values -Is seeded with the current time of day to generate different sequences of numbers each time the program executes