CUBIC and HyStart++ Support in quiche

This post details the integration and testing of CUBIC and HyStart++ congestion control algorithms within Cloudflare's quiche (QUIC) implementation. It explains the concepts of QUIC congestion control, Reno, CUBIC, and HyStart++, and presents lab test results demonstrating that CUBIC and HyStart++ improve performance and significantly reduce packet loss compared to Reno, especially under packet loss conditions. This contributes to the ongoing optimization of Cloudflare's network transport layer for better performance and reliability.