Lossless packet switching with small buffers

Packet switching and the switching of asynchronous transfer mode (ATM) cells depend on buffering. The amount of buffering required by a packet switch is affected by the burstiness of the data stream. Even if the data stream is uniform at its source, the stream may become bursty as it passes through switches and is subject to contention with other data streams. For a network of output buffered switches, if the incoming data streams are periodic, then the streams emerging from the switches after contention are also periodic. By imposing a period on the network, a packet switch can be designed that is lossless even when each input channel operates at its maximum rate, provided that no output channel is overloaded. Such a switch requires relatively small buffers, smaller than the buffers required by a comparable switch with Poisson arrivals. It is also shown that the use of reserved time slots limits the buffering requirements over a sequence of connection establishments and terminations. The advantage of our strategy is that it minimises the size of the expensive high speed optical buffers in the backbone network