Cloudflare, Inc.
Opportunistic transmission control protocol (TCP) connection establishment

Abstract:

A TCP intermediate device receives a first SYN packet from a TCP client to establish a TCP connection between the TCP client and a TCP origin server. Prior to the TCP connection being fully established, the TCP intermediate device transmits a second SYN packet to the TCP origin server. The TCP intermediate device transmits a first SYN-ACK packet to the TCP client. The TCP intermediate device receives a first ACK packet from the TCP client. The TCP intermediate device receives a second SYN-ACK packet from the TCP origin server. The TCP intermediate device transmits a second ACK packet to the TCP origin server as part of establishing the third TCP connection.