Throughput analysis of shared-memory crosspoint buffered packet switches

This paper presents a theoretical throughput analysis of two buffered-crossbar switches, called shared-memory crosspoint buffered (SMCB) switches, in which crosspoint buffers are shared by two or more inputs. In one of the switches, the sharedcrosspoint buffers are dynamically partitioned and assigned to the sharing inputs, and memory is sped up. In the other switch, inputs are arbitrated to determine which of them accesses the shared-crosspoint buffers, and memory speedup is avoided. SMCB switches have been shown to achieve a throughput comparable to that of a combined input-crosspoint buffered (CICB) switch with dedicated crosspoint buffers to each input but, with less memory than a CICB switch. The two analyzed SMCB switches use random selection as the arbitration scheme. We model the states of the shared crosspoint buffers of the two switches using a Markov-modulated process and prove that the throughput of the proposed switches approaches 100% under independent and identically distributed uniform traffic. In addition, we provide numerical evaluations of the derived formulas to show how the throughput approaches asymptotically to 100%. Index Terms Buffered crossbar, throughput, speedup, shared memory, crosspoint buffer.