Visualizing QUIC and HTTP/3 with qlog and qvis

The new QUIC and HTTP/3 (H3) protocols being finalized by the IETF are powerful but also highly complex. They combine advanced approaches from predecessors such as TCP (e.g., congestion and flow control, reliability) and HTTP/2 (H2) (e.g., stream multiplexing, prioritization), with cutting-edge features (e.g., 0-RTT data, connection migration). As QUIC runs on top of UDP, these intricate systems have to be re-implemented from scratch, often in userspace, which has turned out to be error-prone. QUIC also fully integrates TLS 1.3 and is end-to-end encrypted at the transport layer. This means that, unlike with TCP, elements like packet and acknowledgement numbers are indiscernible to passive observers in encrypted packet traces (e.g., .pcap files analyzed with tools like Wireshark). As such, QUIC requires (ephemeral) TLS keys for even high-level analysis, leading to scalability, privacy and security issues. It is clear that QUIC+H3's overall complexity and heavy security focus make them difficult to implement, debug, observe, analyse, use and teach in practice.