[the8472]

My understanding is that window scaling and SACKs enable TCP to detect losses within large segments too. The only limitation is that most congestion controllers throttle back when detecting packet loss. Newer latency-based controllers don't suffer from that problem.

[eadan]

This is interesting. I haven't seen much in regard to comparing TCP+BBR to FASP other than a masters thesis which suggests FASP outperforms on transferring large files over long distances (which is exactly its intended purpose). But, I wonder if splitting a file over multiple QUIC connections and re-assembling at the other side would come closer to the performance of FASP? Could be a fun experiment, I might try it!

[the8472]

An optimal CC should have high utilization with a single stream¹ and behave fairly to other connections on the network. Measuring multiple streams misses the point of the exercise.

> other than a masters thesis which suggests FASP outperforms on transferring large files over long distances

I found that one too. I would take it with a grain of salt since it uses scp for data transfer (which has its own flow control and may be the limiting factor here) and doesn't list the values of some important tcp settings, e.g. tcp_wmem, which can be essential for transoceanic connections.

¹ ignoring the case where a single CPU core can't move bytes fast enough to saturate a link.