Summary: We are introducing Happy Eyeballs v3, a new connection-establishment algorithm that replaces the previous DnsAndConnectSocket-based approach. The new implementation races IPv4 and IPv6 connection attempts in parallel using a Rust-based state machine <https://github.com/mozilla/happy-eyeballs>, and can also race QUIC/HTTP/3 against TCP-based HTTP/1.1 or HTTP/2 when an HTTPS record or Alt-Svc response header indicates that HTTP/3 is available.
Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1953459 Specification: The algorithm is specified in draft-ietf-happy-happyeyeballs-v3 <https://datatracker.ietf.org/doc/draft-ietf-happy-happyeyeballs-v3/>. Standards Body: IETF. Platform coverage: Available on desktop and Android. Preference: network.http.happy_eyeballs_enabled DevTools bug: Not applicable. Extensions Bug: Not applicable. Use Counter: N/A Standards-Positions Discussion: https://github.com/mozilla/standards-positions/issues/1192 Other browsers: - Chromium: According to https://chromeenterprise.google/policies/happy-eyeballs-v3-enabled/ , this has been supported since Chrome 136. - WebKit: No signal yet web-platform-tests: There is no WPT coverage for connection-establishment behavior. We have added xpcshell tests covering H1, H2, and H3 0-RTT accepted/rejected paths, dual-family race scenarios, fallback to IPv4, and LNA denial. Performance: Connections to dual-stack hosts are faster because IPv6 and IPv4 are raced simultaneously rather than tried sequentially. We also expect to see increased HTTP/3 usage, because Happy Eyeballs v3 can race QUIC/HTTP/3 against TCP-based HTTP/1.1 or HTTP/2 and select the faster working path. If you observe unexpectedly long connection times, page not loading, or any regression in connection behavior, please file a bug blocking Bug 1953459 <https://bugzilla.mozilla.org/show_bug.cgi?id=1953459>. Thanks, Kershaw -- You received this message because you are subscribed to the Google Groups "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/mozilla.org/d/msgid/dev-platform/CAMy_zmP1f0i%3DOXwPVyCVckE1dGZUGgf3XqHMM8TPbic6q9u5fw%40mail.gmail.com.
