Reasonable and effective buffer structures are proposed in core routers/nodes of optical burst switching. Based on the model of burst traffics and their contentions, the basic qualifications for designing the buffer structures are concluded. With these qualifications, the structures that integrate buffer with suitching are proposed, moreover, by conclusion and expansion,the classification rules of buffer structures are also proposed from different angles. The schemes of integrated stuctures are analyzed and simulated. The results show that the schemes satisfy the basic qualifications proposed in the paper,and fiber-shared structure should be used without considering the cost. Besides, with the same sharedrange,an output-buffered structure precedes an input-buffered one, especially for the fibershared structures.