Abstract: A low-latency, high-bandwidth, hybrid TDM/WDM architecture for connecting processing nodes into a high-performance computing environment designed as a system area network is disclosed. Each node has a receiver for receiving optical communication within a fibre at all wavelength channels supported by the system simultaneously and individually. Each node also has a transmitter for transmitting at at least two wavelengths. One of the wavelengths is a default wavelength for the node. In order to transmit data, a node requests a channel and is provided with a transmit wavelength at which to transmit data. Other nodes receive the data and, when the recipient is the addressee of the data, the data is then forwarded to a computing device connected to the node or in communication therewith. The architecture provides robust communication with high bandwidth.