Evaluation of 100 Gb/s LAN networks for the LHCb DAQ upgrade

The LHCb experiment[1] is preparing a major upgrade resulting in a need for a high-end network for a data acquisition system. Its capacity will grow up to a target speed of 40 Tb/s, aggregated by 500 nodes. This can only be achieved reasonably by using links capable of coping with 100 Gb/s line rates. The constantly increasing need for more and more bandwidth has initiated the development of several 100 Gigabit/s networks. There are 3 candidates on the horizon, which need to be considered: Intel® Omni-Path, 100G Ethernet and EDR InfiniBand. We present test results with such links both using standard benchmarks (e.g. iperf) and using a custom built benchmark called LHCB-DAQPIPE. The key benefit of these measurements is that we can get to know better the behavior of the system in the early development stage, thus we can find out the limitations of the different network components. This can give an idea as to whether there is a need for more focus on some elements, which can be optimized in the future.