Happy Eyeballs (also called Fast Fallback) is an algorithm published by the

IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and a ...

that makes dual-stack applications (those that understand both IPv4 and

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv ...

) more responsive to users by attempting to connect using both IPv4 and IPv6 at the same time (preferring IPv6), thus minimizing common problems experienced by users with imperfect IPv6 connections or setups. The name "happy eyeballs" derives from the term "eyeball" to describe endpoints which represent human Internet end-users, as opposed to servers. Happy Eyeballs is designed to address the problem that many IPv6 networks are unreachable from parts of the Internet, and applications trying to reach those networks will appear unresponsive, thus frustrating users. Happy Eyeballs solves this problem by determining which transport would be better used for a particular connection by trying them both in parallel. An application that uses a Happy Eyeballs algorithm checks both IPv4 and IPv6 connectivity (with a preference for IPv6) and uses the first connection that is returned. The addresses are often chosen from the DNS with a round-robin algorithm. Implementations of Happy Eyeballs stacks exist in Google's

Chrome web browser Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macO ...

Opera Opera is a form of theatre in which music is a fundamental component and dramatic roles are taken by singers. Such a "work" (the literal translation of the Italian word "opera") is typically a collaboration between a composer and a libr ...

12.10,

Firefox Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current ...

version 13, OS X, cURL and OpenBSD. Happy Eyeball testing was part of

World IPv6 Day World IPv6 Day was a technical testing and publicity event in 2011 sponsored and organized by the Internet Society and several large Internet content services to test and promote public IPv6 deployment. Following the success of the 2011 test day, ...

in 2011. The Happy Eyeballs algorithm may be extended for choosing between types of transport protocols as well, such as TCP and

SCTP The Stream Control Transmission Protocol (SCTP) is a computer networking communications protocol in the transport layer of the Internet protocol suite. Originally intended for Signaling System 7 (SS7) message transport in telecommunication, the p ...

, but development is still in an experimental phase.

References

{{Reflist IPv6 transition technologies

See also

References