1-RTT

RU: 1-RTT

The standard QUIC handshake for a new connection: the client sends its TLS 1.3 ClientHello and QUIC transport parameters in one packet; the server replies with its keys; after one round trip the client can send application data. By contrast, TCP+TLS 1.3 needs 2 RTT (1 TCP + 1 TLS), and TCP+TLS 1.2 needs 3 RTT (1 TCP + 2 TLS).