“In Mac OS X 10.2 Jaguar, Apple introduced IPv6 support. Like other IPv6-capable operating systems, Mac OS will prefer IPv6 over IPv4 if it has a choice,” Iljitsch van Beijnum reports for Ars Technica. “That is, until yesterday’s 10.6.5 Snow Leopard update. With regular IPv6 connectivity, the newly updated Snow Leopard will still try to connect over IPv6 first, but for IPv6 destinations that are reachable over 6to4, the snowy cat prefers IPv4 instead. It will only connect over 6to4 to IPv6 destinations if there’s no IPv4.”
“The apparent rationale for this move is that 6to4 is responsible for a disproportionate share of non-working IPv6 setups,” van Beijnum reports. “Measurements by Google show that simply giving http://www.google.com an IPv6 address means that, subsequently, about 0.1 percent of all Google’s users would be unable to connect to the search giant. That is unacceptable to them, not just from a commercial perspective, but also… how are you going to debug this problem if you’re unable to search the Web? ISPs are unlikely to hold user’s hands if this eventuality comes to pass. Earlier results show that Mac 6to4 users are a huge proportion of the (currently) 0.3 percent of IPv6-capable users. But 6to4 has exactly the properties that make it fail in ways that tend to go unfixed.”
Full article here.
Redpill Linpro’s Tore Anderson writes over in the Apple Mailing Lists, “The 6to4/IPv4 preference problem I’ve posted about a few times earlier appears to be solved in the OS X 10.6.5 previews. I’d like to send a big *thank you* to everyone in Apple involved in making that happen!”
Anderson writes, “However, there’s still some rough edges and in sending this message I’m hoping there’s a chance they too will get included in the final release of 10.6.5.”
Full message here.