Due to the advances in content distribution and data center technologies, the traffic inside metropolitan area network (MAN) becomes more and more distributed. The current MAN architecture that only plays the role of bridge becomes insufficient to handle such new traffic patterns. Hence, the demand for a new MAN architecture is inevitable. It is expected to be both efficient and cost-effective. In this thesis, we proposed Optical Buffer Ring (OBR) as the solution of next generation MAN. It combines both OBS's low end-to-end delay and RPR's low loss rate. And compared to more advanced network architectures based on optical packet switching, OBR is of lower cost and thus more feasible in the near future. To evaluate the performance of OBR, we conducted simulation study over large set of parameters. According to the results, the performance of OBR indeed coincides with our expectation. Furthermore, OBR scales better than both OBS and RPR in that the end-to-end delay of OBR decreases as network size increases while the loss rate increases little with network size. Index Terms¡ÐMAN, WDM, OBS, OBR, RPR, HORNET, LightRing, Diffserv, optical packet switching.