The Supercomputer Supernet testbed: a WDM-based supercomputer interconnect

Current fiber optic networks effectively provide local connectivity among end user computing devices, and can serve as backbone fabric between LAN subnets across campus and metropolitan areas. However, combining both stream service (in which ATM excels) and low latency datagram service (in which cluster networks like Myrinet and POLO excel) has been difficult to realize. This paper describes a new wavelength division multiplexed (WDM) fiber optic network that supports both stream and datagram service and extends reach and functionality of low-latency, high bandwidth workstation clusters to a campus and MAN setting. The novel concept is based on combining the rich interconnect structure of WDM fiber optics with the low-latency mesh of crossbar switches recently developed for workstation groups. This system, called the Supercomputer Supernet (SSN) achieves a high level of performance by replacing the point-to-point copper wire links with a parallel channel (WDM) fiber optic interconnect system. The novel scheme interconnects asynchronous wormhole routing switches used in parallel supercomputers via multi-channel WDM fiber optic links embedded in to an optical star (or tree) "physical" topology, WDM will be used to subdivide the very large fiber bandwidth into several channels, each of Gb/s bandwidth, WDM channels (supporting also time division multiplexing) will be established between modules, thus defining a dense "virtual" interconnection topology, which is dynamically reconfigurable and responds to changing traffic patterns. A pool of channels will be set aside for direct, end-to-end connections between crossbars, providing circuit-switched service for real-time traffic applications.