DAS (Distributed ASCI Supercomputer) is a wide-area distributed cluster designed by the Advanced School for Computing and Imaging (ASCI). The DAS machine is used for research on parallel and distributed computing by five Dutch universities:
The DAS system is funded by NWO (the Netherlands organization for scientific research), SION (the foundation for computer science research in the Netherlands) and the participating universities.
Here is the Myrinet interconnection layout of the VU cluster. The topology is a 3D-mesh, in which dimension order routing is used.
The four DAS clusters are interconnected over the SurfNet4 ATM network, which offers lower latency and higher bandwidth than the standard Internet connections between the sites. Every site has a special gateway host, which routes inter-cluster packets from the FastEthernet network over the wide area ATM links. It is important to mention that the links are actually Constant Bitrate (CBR) virtual circuits, offering guaranteed and reliable performance. This makes the behaviour and run time of applications run on the wide-area DAS much more predictable than would otherwise be the case. An overview of the planning for this part of the project is available.
The ATM links between the four clusters are fully operational since October 1998. At the moment they have a capacity of 6 Mbit/sec. The roundtrip latency between the sites is between 1.5 and 3.7 msec, mainly depending on the distance (fotons and electrons do have a speed limit unfortunately). An overview of the current network status is maintained at the Utrecht site.
Currently we only run IP over ATM; we might additionally be using native ATM at the application level later on.