On October 25, we will try to turn off IPv6 transition technologies Teredo and 6to4

In 2018, in my article Phasing out IPv6 transition technologies, I brought information about the current development and use of Teredo and 6to4 technologies. In conclusion, I informed that Teredo prefix 2001::/32 is no longer promoted to foreign upstreams, but only within NIX.CZ and NIX.SK peering nodes, where global peers are active as well, so we did not limit the 6to4 technology due to certain traffic from abroad. In this blogpost, I will explain why we now want to turn off these two technologies.