Google: PCIe Non-Transparent Bridge they're independent systems with a special PCIe switch that looks like an end device to all participants and allows shuffli

Google: PCIe Non-Transparent Bridge they're independent systems with a special PCIe switch that looks like an end device to all participants and allows shuffling data around at PCIe performance (the NTB function is integrated on some Intel processors AFAIK, but it may also be a separate chip)