Smaller clusters will typically employ from four to thirty-two nodes. Beowulf clusters are usually based on the Linux operating system. Ethernet is cost-effective since it is a standard feature on the iMac and Power Macintosh computer systems.
Ethernet also has the advantage of distributed deployment.
As the number of nodes increases, the performance of a switched ethernet solution declines markedly. This is due to limitations in ethernet switching technology. These limitations can be overcome through the use of a high-speed switching fabric. A switching fabric usually consists of a PCI card in each desktop system linked to a multi-dimensional switch using special purpose cables. At the software level, communications between nodes in a cluster are handled by middleware.