Boosting Event Building Performance using Infiniband FDR for the CMS Upgrade

As part of the CMS upgrade during CERN's shutdown period (LS1), the CMS data acquisition system is incorporating Infiniband FDR technology to boost event-building performance for operation from 2015 onwards. Infiniband promises to provide substantial increase in data transmission speeds compared to the older 1GE network used during the 2009-2013 LHC run. Several options exist to end user developers when choosing a foundation for software upgrades, including the uDAPL (DAT Collaborative) and Infiniband verbs libraries (OFED). Due to advances in technology, the CMS data acquisition system will be able to achieve the required throughput of 100 kHz with increased event sizes while downsizing the number of nodes by using a combination of 10GE, 40GE and 56 Gb Infiniband FDR. This paper presents the analysis and results of a comparison between GE and Infiniband solutions as well as a look at how they integrate into an event building architecture, while preserving the scalability, efficiency and deterministic latency expected in a high end data acquisition network.