I have had a lot of experience with Ethernet (of course) but absolutely zero experience with InfiniBand because access to it usually requires there be a high-performance computer cluster around of some kind. Here’s one of those things that going to a good school might have provided. Another option would be to intern for any project related to HPC deployments, which would probably require extensive hardware and network experience to qualify for in the first place.
Given the footprint of InfiniBand within the Enterprise for HPC this needs to be elevated in priority for anyone looking into infrastructure engineering as an occupation.