[tcpm] CUBIC rfc8312bis / WGLC Issue 3

[Markku Kojo <[e-mail]>]

Hi all,

this thread starts the discussion on the issue 3: the incorrect way of
setting alpha to 1 when in the fast convergence mode within the 
Reno-friendly region (Issue 3 a) and the issue of setting Wmax for a 
congestion event arriving when in slow start (Issue 3 b):


3 a) The rule for changing alpha to 1 when Wmax is reached in the
      Reno-friendly region is the correct thing to do during the normal
      steady state. However, it is incorrect action to take when in the
      fast convergence mode within the Reno-friendly region because it
      would act just *opposite* to what CUBIC should do when in the fast
      convergence mode; instead of slowing down the increase rate during
      congestion avoidance it actually accelerates because alpha becomes
      increased to 1 earlier than when not in the fast convergence mode.
      This seems an obvious mistake with the quite recent modifications
      to the rfc8312bis.

3  b) Wmax needs to be set differently for a congestion event arriving
      when in slow start and when in congestion avoidance
      If Wmax is set for a congestion event arriving when in slow start
      like currently specified, it results in Wmax with a value that is
      two times higher than the intended Wmax value (the co-authors who
      are the original developpers of CUBIC have agreed on this).

Thanks,

/Markku