HTTP/3 and the QUIC Internet Protocol

a year ago

HTTP/2 improved efficiency by multiplexing requests over a single TCP connection but faced issues like Head-of-Line Blocking and Connection Persistence.
QUIC (Quick UDP Internet Connections) was developed by Google in 2012 to overcome TCP's limitations by operating over UDP and incorporating its own reliability mechanisms.
QUIC uses a unique Connection ID (CID) for tracking connections, enabling seamless network switches without dropping the connection.
QUIC eliminates Head-of-Line Blocking by monitoring streams independently, allowing other streams to continue even if one loses a packet.
QUIC integrates encryption into its handshake, reducing latency compared to TCP's separate TLS handshake.
QUIC's handshake involves exchanging SCID, DCID, cipher suites, and certificates to establish a secure connection.
QUIC packets include headers with SCID, DCID, and packet numbers, and data parts with STREAM frames for multiplexing.
HTTP/3 was created to work with QUIC, retaining HTTP/2's stream-based architecture but delegating multiplexing to QUIC.
HTTP/3 introduces request, control, and push streams, each mapped to QUIC streams for efficient data transfer.
HTTP/3 frames include DATA, HEADERS, SETTINGS, and GOAWAY, used for requests, responses, configuration, and connection termination.
QUIC and HTTP/3 are widely adopted, with ~34% of websites using HTTP/3, including major platforms and browsers.

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