Cloudflare Calls: millions of cascading trees all the way down

What this post added

This post details the technical implementation of Cloudflare Calls, a new WebRTC infrastructure service. It explains how Cloudflare leverages its global network and Anycast architecture to provide a distributed SFU. Key technical details include using a single IP address per protocol for DTLS, ICE, STUN, SRTP, and SCTP, with L4 load balancing using the 4-tuple hash. It highlights the challenge of DTLS packets lacking connection identifiers and the need for every server to handle them, requiring certificates for decryption. The post also discusses the use of the HTTPS API for offer/answer exchange and its interaction with ICE connectivity checks, and the challenges of slow replies to ICE checks observed in earlier implementations.