The QUIC protocol

QUIC is a general-purpose network protocol built on top of UDP. The protocol is still under development and standardized by the IETF. Quinn, which DotQuic uses, strives to implement the latest draft but may lag a bit behind. Although QUIC is still in a draft phase, the protocol is used for all connections from Chrome web browsers to the Google servers.

QUIC solves a number of transport-layer and application-layer problems experienced by modern web applications. It is very similar to TCP+TLS+HTTP2, but implemented on top of UDP. Having QUIC as a self-contained protocol allows innovations which aren’t possible with existing protocols as they are hampered by legacy clients and middleboxes.

Key advantages of QUIC over TCP+TLS+HTTP2 include:

• Improved connection establishment speed (0-rtt).
• Improved congestion control by moving congestion control algorithms into the user space at both endpoints.
• Improved bandwidth estimation in each direction to avoid congestion.
• Improved multiplexing without head-of-line blocking.
• Contains forward error correction (FEC).

While QUIC's intentions are originally web-oriented, it offers interesting opportunities in other areas like game networking. One thing is for sure, QUIC has many great potentials and will serve us in the future with HTTP/3.