The nature of the computational problem, and to a lesser extent, the programming model, dictates the degree of communication that is required.
Some computations require extremely low latency communications to provide acceptable performance.
Other technologies of similar speed, such as FDDI, are at least an order of magnitude more expensive, and provide inferior performance. Netgear is the consumer products division of Bay Networking. For small clusters of up to four nodes, we measure better performance with a hub, and the hub is less expensive. Hubs must operate in half duplex while switches can operate in either half or full duplex. The reason a hub is faster in small clusters is that FE switches must completely receive a packet before retransmitting it, while hubs overlap reception and transmission.