I deployed a custom implementation of IETF BBR on FreeBSD at one of the major CDNs, Limelight, that was wildly successful for the company. One bit of wisdom I

I deployed a custom implementation of IETF BBR on FreeBSD at one of the major CDNs, Limelight, that was wildly successful for the company. One bit of wisdom I will share after having worked in this space for a few years, depending on what you're optimizing for, it's pretty easy to out-muscle the competition and make a "better" CC for your own selfish purposes at a small or large scale. The real challenge in this space is balancing flow fairness, link utilization, buffering delay, heuristics or models to differentiate congestion from unrelated signals like RF interference causing channel loss, and making the whole thing computationally inexpensive. It's further difficult because the internet is a free for all, in a closed network flow control between each hop would make congestion control unnecessary as you could use a congestion avoidance algorithm instead. Fibre channel is an example of that in wide use with its credit based flows.