> For the complete documentation index, see [llms.txt](https://http3-explained.haxx.se/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://http3-explained.haxx.se/zh/the-protocol/feature-handshakes.md).

# 快速握手

QUIC提供0-RTT和1-RTT的连接建立，这意味着QUIC在最佳情况下不需要任何的额外往返时间便可建立新连接。其中更快的0-RTT仅在两个主机之间建立过连接且缓存了该连接的“秘密”（secret）时可以使用。

## 早期数据（Early data）

QUIC允许客户端在0-RTT的情况下直接捎带数据。这使得客户端能尽早向对方传送数据，当然也使得服务器能更快地发回数据响应。


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