I'm not sure about the typical demands on the fabric of FE-type codes, but a typical HPC cluster (university or national) is likely to spend much of its time on

I'm not sure about the typical demands on the fabric of FE-type codes, but a typical HPC cluster (university or national) is likely to spend much of its time on materials science work using DFT, which requires low latency rather than high bandwidth for short messages. Somewhere under http://archer.ac.uk http://archer.ac.uk there are usage statistics as an indication of the workload, though it varies month-to-month.