TCP Cubic and LinuxReno cwnd should not grow during application-limited phase
Section 5.8 of RFC 9438 for TCP Cubic now specifies that cwnd should not grow during an application limited phase. However, ns-3 TCP will do so, and the tutorial fifth.cc is an example program that can show such window growth, because the tutorial app uses a CBR flow. Note that the previous versions of Cubic and RFC 5681 did not prescribe that limit, but the new Cubic RFC (and Linux) will limit, so I believe that we should follow Linux and the updated RFC.
Linux Reno congestion avoidance applies the same limit.
Edited by Tom Henderson