Given their configuration of just 4U spread across 17 racks, there's likely a bunch of compute in the rest of the rack, and 1-2 top of rack switches like this:
And then you connect the TOR switches to higher level switches in something like a Clos distribution to get the desired bandwidth between any two nodes:
https://www.qct.io/product/index/Switch/Ethernet-Switch/T700...
And then you connect the TOR switches to higher level switches in something like a Clos distribution to get the desired bandwidth between any two nodes:
https://www.techtarget.com/searchnetworking/definition/Clos-...