HTTP/1.1 vs HTTP/2 vs HTTP/3 (QUIC)
Trace the evolution of the web transport layer: Head-of-Line blocking, binary framing, multiplexing, HPACK/QPACK header compression, and UDP-based QUIC.
01.1. HTTP/1.1: The Baseline and its Structural Bottlenecks
Standardized in RFC 2616 (1997), HTTP/1.1 powered the modern web for nearly two decades. However, as web pages evolved from simple HTML documents to complex web apps requiring 100+ subresources (JS, CSS, images, fonts), HTTP/1.1 encountered severe physical limits:
- Application-Layer Head-of-Line (HoL) Blocking: On a single TCP connection, requests must be processed serially. If Request 1 is a slow database query, Request 2 must wait in line behind it, even if Request 2 is ready instantly.
- The 6-Connection Browser Workaround: To mitigate HoL blocking, modern browsers open up to 6 parallel TCP connections per domain. This consumes excess server memory, multiplies TCP handshake overhead, and triggers "Domain Sharding" hacks (
cdn1.example.com,cdn2.example.com). - Redundant Plaintext Headers: Every single HTTP/1.1 request transmits 500 to 2,000 bytes of uncompressed ASCII headers (Cookies, User-Agents, Cache-Control), wasting significant upstream mobile bandwidth.
The Evolution of Web Protocols: HTTP/1.1 vs HTTP/2 vs HTTP/3 (QUIC) ð
The Evolution of Web Protocols: HTTP/1.1 vs HTTP/2 vs HTTP/3 (QUIC) ð
How web transport evolved from single-file HTTP/1.1 pipelining to HTTP/2 binary multiplexing, and finally to UDP-based QUIC eliminating TCP Head-of-Line blocking.
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