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1325Re: NewReno and the 2001 Revision

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  • Mark Allman
    Sep 25, 1998
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      > As Sally pointed out in the IETF meeting, we can easily come up
      > with scenarioes where NewReno and its variants work badly or too
      > aggressively. But with SACK, we can do better.

      I think no matter what TCP we have, we can always come up with
      scenarios where things don't work particularly well. I have seen
      presentations on situations in which SACK based algorithms are
      suboptimal, as well.

      > As of now, there is no internet draft on how to make good use of
      > SACK. I think in 1 year's time, SACK should be widely deployed.
      > So we should focus on how to make good use of SACK info, and also
      > how to avoid abusing it.

      OK, I am with you on the last statement. We don't want people to
      abuse SACK information and make an inappropriately agressive TCP.
      That is why we inserted the statement on SACK in 2001.bis. The
      paragraph essentially says that SACK algorithms must follow the
      spirit of the non-SACK congestion control algorithms (see the
      statement in the draft for a better (I hope!) description).

      But, at this point I am not sure that the research into a SACK-based
      algorithm is done, or near a point where it is time to determine
      which algorithm is ``the best'' and standardize it. So, it seems to
      me that the appropriate approach is to outline the general
      principles that should guide the development of SACK-based
      algorithms, in order to prevent such algorithms from hurting the
      network and contributing to congestion collapse. However, it seems
      less important to try to decide which SACK-based algorithm is the
      best and standardize it (at least at this time).

      But, I've been wrong before...

      allman
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