The CMS event builder demonstrator based on Myrinet

The data acquisition system for the CMS experiment at the large hadron coll ider (LHC) will require a large and high performance event building network . Several switch technologies are currently being evaluated in order to com pare different architectures for the event builder. One candidate is Myrine t. This paper describes the demonstrator which has been set up to study a s mall-scale (8x8) event builder based on a Myrinet switch. Measurements are presented on throughput, overhead and scaling for various traffic condition s. Results are shown on event building with a push architecture.