The InfiniBand based Event Builder implementation for the LHCb upgrade

The LHCb experiment will undergo a major upgrade during the second long shutdown (2019 - 2020). The upgrade will concern both the detector and the Data Acquisition system, which are to be rebuilt in order to optimally exploit the foreseen higher event rate. The Event Builder is the key component of the DAQ system, for it gathers data from the sub-detectors and builds up the whole event. The Event Builder network has to manage an incoming data rate of 32 Tb/s from a 40 MHz bunch-crossing frequency, with a cardinality of about 500 nodes. In this contribution we present an Event Builder implementation based on the InfiniBand network technology. This software relies on the InfiniBand verbs, which offers a user space interface to employ the Remote Direct Memory Access capabilities provided by the InfiniBand network devices. We will present the performance of the software on a cluster connected with 100 Gb/s InfiniBand network.