Google plans for a QUICker web with UDP connections

Google hopes that Quick UDP Internet Connections (QUIC), recently added to Chrome Canary, will help speed up HTTP traffic on the internet. The goal here is not to compete with SPDY, the protocol introduced four years ago, but to work in tandem with it by replacing TCP (Transmission Control Protocol), the current transport method, with UDP (User Datagram Protocol).

TCP makes sure that no data packets go missing at the protocol level and that they all land at their destination in the correct order. In Google's opinion, that's a disadvantage when combined with SPDY, in which several data streams between a browser and a web server flow over a single TCP socket – just one misplaced packet would block all of the data streams. The TCP stack in this case would also slow down the transmission of all of the streams.

QUIC uses the simpler UDP, which does not guarantee the transmission of individual packets. That means that the new protocol has to take care of this itself, but unlike with TCP, connections not affected by a particular loss don't have to wait for a new transmission. QUIC is designed to ensure fast connections, reduce packet losses with transmission pacing and minimise latency in the case of retransmission of a packet with forward error correction, and like SPDY, it only allows encrypted connections.

An extensive Google Docs document lays out the details and considerations behind QUIC. The Chromium source code includes a sample implementation for the server and the code for the client-side.

(djwm)