[e2e] Is a non-TCP solution dead?

[Mark Allman]

> ABC went experimental (proof that the IESG is stuck on Planet
> Status Quo?[*]), and RFC3465 discusses concerns about the extra
> burstiness that it introduces. Turn off delacks, and you
> counteract some of that burstiness now you're counting acks
> properly.

Two things...

  * First, a bit of defense of the IESG for just a moment.  I
    requested ABC go experimental.  I'd like to see a bit more
    experience.  While they could certainly have said "no, let's go
    for standards track" and maybe you think they should have, I
    just want to note that the original notion came from me.  For
    their part, they added a "Statement of Intent" to the RFC that
    basically says the intent is to put this on standards track.

  * IMO, turning off delayed ACKs to counteract the burstiness of
    ABC doesn't really counteract the right kind of burstiness.  The
    RFC discusses "microburstiness" (line rate burst in response to
    a single ACK) and "macroburstiness" (increase in the cwnd over a
    single RTT).  Simply ACKing every packet mitigates the
    microburstiness -- which I don't see as a big deal with ABC (the
    increase is 1 packet per ACK over packet counting).  But, ACKing
    every packet doesn't deal with the macroburstiness at all.  And,
    I think the macroburstiness is the potential problem.  While I
    believe the spirit of VJCC is that we double the cwnd every RTT
    during slow start the practice is that we increase by 50%.  So,
    a remaining question in my mind is whether ABC is really
    overly-aggressive for the network or not.

allman


--
Mark Allman -- BBN/NASA GRC -- http://roland.grc.nasa.gov/~mallman/