A critical design feature of Spanner is owning the packets end-to-end (as in, between data centers and across oceans). This lets Google minimize the "A" in "CAP

A critical design feature of Spanner is owning the packets end-to-end (as in, between data centers and across oceans). This lets Google minimize the "A" in "CAP", and would be quite difficult to replicate outside of a network like Google's SDN. Spanner is the software, plus the network, plus the hardware. (work on Google Cloud)