The Internet is running out of standard 32-bit IPv4 addresses, and the switch to the 128-bit IPv6 format has been underway for awhile. Apple believes the move has progressed sufficiently for them to consider IPv6 mainstream, and has prioritized IPv6 in the public betas of both iOS 9 and OS X 10.11 El Capitan.
In a message to the Internet Engineering Task Force (IETF) mailing list, David Schinazi, an engineer on Apple’s CoreOS Networking team, said that the platforms now both use ~99% IPv6 connections, up from 50% in iOS 8 and OS X 10.10.
The change is thanks to an updated version of the “Happy Eyeballs” algorithm that automatically detects and chooses the protocol based on whichever responds fastest.
The algorithm is used by the devices to determine which protocol should be used. Many apps use a “dual stack” approach to networking, making both protocols available. Schinazi says that “IPv6 is now mainstream instead of being an exception.”
Schinazi believes this will likely mean more IPv6 traffic for websites and app builders, saying that “if this behavior proves successful during the beta period, you should expect more IPv6 traffic from Apple products in the future.”