On Thu, 28 Mar 2013, Douglas Otis wrote:
IPv6 makes publishing IP address reputations impractical. Since IP address reputation has been a primary method for identifying abusive sources with IPv4, imposing ineffective and flaky replacement strategies has an effect of deterring IPv6 use.
My belief is that IP address reputation has always been flakey, it's just vastly more so with IPv6.
What we need is a way to identify a "entity" subnet size. This work is probably wasted on IPv4, but it's definitely needed for IPv6. The ISP in question needs to be able to publish customer/entity subnet size so reputation can be done at this level.
This information might today be available using whois to the RIR, but that's not very practical publication method for quick lookups.