Combined input-crosspoint buffered packet switch with flexible access to crosspoints buffers

The performance of Internet routers is greatly defined by the adopted switch architecture. Combined input-crosspoint buffered (CICB) packet switches are being considered of research interest because of their high switching performance. One of the main requirements in these switches is that the amount of memory needed to achieve 100% throughput under flows with high data rates must be proportional to the number of ports and crosspoint buffer size, which is set by the distance between the line cards and the buffered crossbar. Therefore, long distances between the line cards and the buffered crossbar can make a CICB switch costly to implement or infeasible. In this paper, we propose and discuss two CICB packet switches with flexible access to crosspoint buffers. The proposed switches allow an input to use any available crosspoint buffer at a given output, instead of having rigid access where an input can only access a dedicated crosspoint buffer at a given output, as is the case on previous existing architectures. The proposed switches provide high switching performance and support long distances between the buffered crossbar and the line cards, while using crosspoint buffers of small size. Our switches reduce the required crosspoint buffer size by a factor of N, where N is the number of ports, keep service of cells in sequence, and use no speedup.