IPv6 only has space for 10^19 networks, so you would need to heavily chop up /64s if you wanted to number the universe. But IP is not designed for high-latency

IPv6 only has space for 10^19 networks, so you would need to heavily chop up /64s if you wanted to number the universe. But IP is not designed for high-latency networks, so this only really matters if FTL communication is invented.