RFC8312 Cubic

[Scheffenegger, Richard]

Hi,

we encounted an issue with the BSD11 cubic implementation during testing, when dealing with app-stalled and app-limited traffic patterns.

The gist is, that at least in the after_idle cong_func for cubic, the states for ssthresh and cubic epoch time are not reset, leading to excessive cwnd values (overflows even) and self-inflicted drops due to dramatic burst transmissions.

Bug Report, or Patch directly to Phabricator (when it is fully qualified)?

Best regards, 
   Richard