Practical PCIe gen3 fabric switches?

[WeekendWarrior]

If we go back to 2016-19, numerous press releases described (seemingly) upcoming releases of PCIe gen3 fabric switches. FWIW, a fabric switch operates like a conventional ethernet switch (interconnecting multiple hosts) while a "fanout switch" expands the number of devices a single host can support.

A search for actual commercial products providing PCIe gen3 fabric switching did not result in much. Little or no used market appears to exist.

Does anyone have perspective on actual products?

 

[twin_savage]

PCIe traffic doesn't contain routing information so you can't really have multiple hosts sharing a pool of devices outside of some very very specific architectures that are tailor made for businesses. The Dell VRTX is probably one of the more flexible examples of this, but it is only PCIe 2.0.

PCIe bifurcation has taken the place of what a "fanout switch" might have served; the only product i can think of that uses them offhand are the new Mac Pros.

There was a whole "composable infrastructure" craze that went on years ago but it turned out that in practice, locality matters and you will throw away large amounts of performance by making tightly integrated pieces of infrastructure composable and disaggregated .
Its possible that some of the bleeding edge CXL features might revive more flexible/fluid PCIe setups though, we'll see.

 

[CyklonDX]

You would be looking at infiniband switches.