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It might be worth relaxing filtering within 2001::/16. The RIPE NCC appears to be making /48 PI assignments from within 2001:678::/29 (e.g. the RIPE Meeting next week will be using 2001:67c:64::/48)

Why the whole /16 rather than just that /29 and a few other blocks set aside for /48s?

Indeed, and why jumble these up, there's enough space to keep different allocation types separate and have no confusion with just a few trivial filters, universally deployed, which I suggest is the only way to stop degeneration. If one ISP deviates it creates pressure on others to accept the same. Then we're heading for another v4 mess as people will continuously push the boundary.

There are a lot of /48s in a /16, so protecting against someone accidentally deaggregating their allocated /32 into / 48s seems legitimate.

And some will deaggregate to protect against others advertising more specifics brandon