while i am not a "cloud expert", i'm pretty sure that google datacenters have more than one switch. furthermore, while the precise datacenter layout is probably secret, i infer that the the compute servers and the data servers cannot be housed in the same or nearby racks, since both are independently provisionable and can be arbitrarily attached. for example, if i start a vm and connect a drive, even if google could put them right next to each other in the datacenter, what happens if i start another vm, which for fragmentation reasons gets placed way on the other side of the building, detach the drive and connect it to this new one?
therefore, there must at least be several switches between the devices, and realistically, probably one or more routers.
therefore, there must at least be several switches between the devices, and realistically, probably one or more routers.