There are two mechanisms that can be used to eliminate a round trip for subsequent TLS connections (discussed below):
- TLS session IDs
- ServerHello时，server生成一个32字节的session ID给client，后面的TLS握手client可以在它的ClientHello里发送这个id，server就会restore the cached TLS context and avoid the 2nd round trip of TLS handshake
- nginx支持该方式
- ssl_session_cache
- ssl_session_timeout
- TLS session tickets
与session IDs类似，只是session信息保存在client