HTTP/3 Reference
Reference 为 HTTP/3 遍历 QUIC: eliminating TCP head-of-行 blocking 具有 UDP-based transport.
QUIC Transport
HTTP/3 runs over QUIC, a UDP-based transport with built-in encryption (TLS 1.3). QUIC eliminates TCP-level head-of-line blocking: packet loss affects only the stream waiting for that packet. Connection migration allows changing IP addresses (e.g., WiFi to cellular) without reconnecting. 0-RTT connection resumption enables near-instant reconnects. QUIC integrates flow control, congestion control, and reliability at the application layer.
- UDP-based
- No TCP HOL blocking
- 0-RTT
- Fast resumption
- migration
- IP change OK
per-stream losscached handshakeconnection IDHTTP/3 Features
HTTP/3 reuses HTTP/2 semantics (methods, status codes, headers) with a different framing layer over QUIC streams. QPACK compresses headers similarly to HPACK but handles out-of-order delivery. Server push is removed in HTTP/3. The protocol is negotiated via the Alt-Svc header or DNS HTTPS records. Adoption is growing but requires UDP support, which some networks block. QUIC's encryption is mandatory and non-optional.
- semantics
- Same as HTTP/2
- QPACK
- Header compression
- Alt-Svc
- Negotiation
methods, statushandles reorderingalt-svc: h3=":443"