Switchless event building farm for the Belle data acquisition system

We designed a switchless event building farm for the Belle experiment at the KEKB e/sup +/e/sup -/ collider, as a replacement of the existing event builder and the online farm systems. In the new system, PCs are directly interconnected with multiple point-to-point Fast and Gigabit Ethernet, to build the detector data in two steps and to perform distributed event processing. We set up a test system and confirmed the event building performance meets our new requirements using realistic prototype software. We plan to install the system during the summer shutdown time of 2001.