A large-scale asynchronous transfer mode switch architecture

This paper proposes an asynchronous transfer mode (ATM) switch architecture to realize a large‐scale ATM exchange to be used for the future spreading era of ATM networks. The proposed switch architecture is based on a three‐stage Clos network which consists of many element switches to obtain a large‐scale ATM switch. In the proposed ATM switch, the element switches at the first‐and last‐stage of the Clos network are the shared buffering ATM switches; the element switches at the second stage are the input buffering ATM switches. Because it is preferable to build various capacities of ATM switches in the same way with the three‐stage Clos network architecture, the element switches of the second stage of Clos network should be scalable. Therefore, it is proposed that the second stage switches are the input buffering ATM switches. On the other hand, the first‐ and last‐stage switches are the shared buffering ATM switches to prevent degradation of cell loss rate. The proposed architecture has been evaluated by computer simulations, and it shows that internal link speed‐up and flow control prevent the degradation of cell loss rate. It also shows that degradation of cell loss rate can be ignored even when the ATM switch size is expanded.