ATOLL-a next generation system area network

ATOLL (Atomic Low Latency) is the synonym for a new cluster technology centered around an ASIC chip design integrating all logic parts of a complete System Area Network. Besides its unique architecture, ATOLL extends the hardware support for data transfer over the network to a limit, thus reducing communication latencies and enhancing concurrency. The paper presents the chip´s key functionality (the mechanisms for the send- and receive-operations), in detail, but also illuminates some of the features newly invented with ATOLL. The latter cover such different items as an advanced interface for direct support of user-level communication, special locking modes allowing atomic access or techniques to clear network blocking: all intended to overcome the drawbacks of current SAN implementations.