[Cake] lan keyword affects host fairness

[Pete Heist]

It seems that the ‘lan’ keyword (and probably other lower rtt settings in general) may adversely impact host fairness in some cases. Is this to be expected? I set up a fairness test with rrul_be_nflows where one client has 2/2 TCP flows and the other has 8/8 TCP flows, then ran five tests:

https://docs.google.com/spreadsheets/d/1SMXWw2fLfmBRU622urfdvA_Ujsuf_KQ4P3uyOH1skOM/edit?usp=sharing

As can be seen, fairness works well with the default rtt, but with the lan keyword, it varies from partially fair when rate limiting is used to as if there’s no fairness at all when unlimited (bql) is used. So either we could find some problem with my test, or this may at least need to be documented somewhere...

Pete