I think you mean NAT64/DS-Lite/MAP (which are all types of carrier-grade NAT), since 6to4 is just a means of connecting two IPv6 endpoints across an IPv4 tunnel

I think you mean NAT64/DS-Lite/MAP (which are all types of carrier-grade NAT), since 6to4 is just a means of connecting two IPv6 endpoints across an IPv4 tunnel. This photo sums up the problem with relying on CGN: https://www.flickr.com/photos/jfesler/6751925977/ https://www.flickr.com/photos/jfesler/6751925977/ When an ISP funnels multiple users through the same IPv4 address, you can no longer use IP-based bans without inflicting collateral damage. One way around this problem is for both the ISP and the website to support bigger addresses.