Tidbits & the "NANOG Community" ... with respect to jumping from 32-bits to 64-bits many UNIX-to-UNIX users have noted... ONE more bit (33) may be enough to distinguish Legacy from New. The bit would go on the Left as opposed to Right which would double the existing mess. ... Linux has the added bit ready in the SPARE bit and the Left-most TTL bit deprecated to 0 years ago. A Source+Destination pair is needed for full interchange between Legacy and New. A single bit would be isolated planes. ... Based on a survey of IPv4 Address Space the "NANOG Community" does not appear to involve many critical back-bones or infrastructure. In some circles that would not be considered "On the Internet". YMMV