A new bursty assigned traffic model is suggested

its detailed definition given and the performance analysis and comparison made of the switch fabric in Optical Burst Switching（OBS） by using this model and by the conventional non-bursty assigned traffic model.The calculation results show that when the fanout ratio of the switch fabric F=1 and the bursty intensity Bi=2

the packet loss rate under the burst assigned traffic model will increase by about one order of magnitude than under the non-bursty assigned traffic model.Perhaps the new bursty assigned traffic model cannot be used to reflect the traffic flow in reality

but it offers an analytical approach of approximation to the real traffic flow.