Shared-memory combined input-crosspoint buffered packet switch for differentiated services

Combined input-crosspoint buffered (CICB) packet switches with dedicated crosspoint buffers require a minimum amount of memory in the buffered crossbar of N ² k L bytes, where N is the number of ports and k is the crosspoint buffer size, which is defined by the distance between the line cards and the buffered crossbar, and L is the cell (packet) size in bytes, to avoid buffer underflow under high-speed data flows. To support P traffic classes with different priorities, CICB switches requires N ²k L P bytes to avoid blocking of high priority cells. In this paper, we study a shared-memory crosspoint buffered packet switch that uses small crosspoint buffers and no speedup to support differentiated services and long distances between the line cards and the buffered crossbar in practical implementations. The proposed switch requires 1/m of memory amount in a CICB switch to achieve similar throughput performance.