We proposes a new ATM switch architecture based on tandem-crosspoint ATM switch architecture with input and output buffering. The switch is constructed from a number (K) of crossbar switch planes. Each crosspoint provides a cell buffer. The corresponding crosspoints of these crossbar switches are connected in tandem. Hence we call these K connected crosspoints a tandem-crosspoint.
A cell from the head of input buffer moves first to the first crosspoint of its destination tandem-crosspoint and from there it may moves to the next crosspoint and so on. Each tandem-crosspoint can keep at most K cells at a time. These switch planes perform switching simultaneously. Therefore, each output buffer can receive K cells at most within a time slot.In order to mantain cell sequence, in a tandem-crosspoint, only the cell with the highest priority, which occupies the nearest crosspoint to the K-th can participate in the arbitration employed by the switch plane where it belongs.
We compare the switch to the previously proposed TDXP switch of the same architecture and we find that it can achieve a remarkably higher performance, in terms of throughput and mean delay. This is due to the fact that our proposed switch can keep more cells in its tandem-crosspoint than the TDXP switch does. Our results are based on various traffic models. This switch architecture requires neither an internal speed advantage nor cell resequencing.