Re: [tcpm] [Technical Errata Reported] RFC8312 (5907)

[Neal Cardwell <[e-mail]>]

On Thu, Nov 14, 2019 at 12:53 PM Neal Cardwell <[e-mail]> wrote:
>
> On Thu, Nov 14, 2019 at 12:12 PM RFC Errata System
> <[e-mail]> wrote:
> >
> > The following errata report has been submitted for RFC8312,
> > "CUBIC for Fast Long-Distance Networks".
> >
> > --------------------------------------
> > You may review the report below and at:
> > https://www.rfc-editor.org/errata/eid5907
> >
> > --------------------------------------
> > Type: Technical
> > Reported by: Elliott Ecton <[e-mail]>
> >
> > Section: 5.1
> >
> > Original Text
> > -------------
> >  +--------+----------+-----------+------------+-----------+----------+
> >    |   Loss |  Average |   Average |      CUBIC |     CUBIC |    CUBIC |
> >    | Rate P |    TCP W |   HSTCP W |   (C=0.04) |   (C=0.4) |    (C=4) |
> >    +--------+----------+-----------+------------+-----------+----------+
> >    |  10^-2 |       12 |        12 |         12 |        12 |       12 |
> >    |  10^-3 |       38 |        38 |         38 |        38 |       59 |
> >    |  10^-4 |      120 |       263 |        120 |       187 |      333 |
> >    |  10^-5 |      379 |      1795 |        593 |      1054 |     1874 |
> >    |  10^-6 |     1200 |     12279 |       3332 |      5926 |    10538 |
> >    |  10^-7 |     3795 |     83981 |      18740 |     33325 |    59261 |
> >    |  10^-8 |    12000 |    574356 |     105383 |    187400 |   333250 |
> >    +--------+----------+-----------+------------+-----------+----------+
> >
> >                                   Table 1
> >
> > Corrected Text
> > --------------
> >  +--------+----------+-----------+------------+-----------+----------+
> >    |   Loss |  Average |   Average |      CUBIC |     CUBIC |    CUBIC |
> >    | Rate P |    TCP W |   HSTCP W |   (C=0.04) |   (C=0.4) |    (C=4) |
> >    +--------+----------+-----------+------------+-----------+----------+
> >    |  10^-2 |       12 |        12 |          3 |         6 |       11 |
> >    |  10^-3 |       38 |        38 |         19 |        33 |       59 |
> >    |  10^-4 |      120 |       263 |        120 |       187 |      333 |
> >    |  10^-5 |      379 |      1795 |        593 |      1054 |     1874 |
> >    |  10^-6 |     1200 |     12279 |       3332 |      5926 |    10538 |
> >    |  10^-7 |     3795 |     83981 |      18740 |     33325 |    59261 |
> >    |  10^-8 |    12000 |    574356 |     105383 |    187400 |   333250 |
> >    +--------+----------+-----------+------------+-----------+----------+
> >
> >                                   Table 1
> >
> > Notes
> > -----
> > The CUBIC average window sizes for 10^2 and 10^3 are incorrect in the original text using expression 6.
>
> I strongly suspect that the original text is correct.
>
> Note that the proposed edit would cause the average congestion window
> size of CUBIC to be below that of "TCP W", the Reno [RFC5681] window,
> in the cases with loss rates of 10^-2 and 10^-3. But as mentioned in
> section 4.2. "TCP-Friendly Region", where the native CUBIC curve
> computation produces a target congestion window that is lower than the
> congestion window Reno would use, the CUBIC algorithm instead uses the
> Reno target congestion window. So the average congestion window size
> of CUBIC should not be below that of Reno. I believe that is why in
> the original table the average congestion window for "TCP W" and CUBIC
> match in cases with loss rates of 10^-2 and 10^-3 and with CUBIC using
> C=0.04 or C=0.4.
>
> Are there tests or simulations showing CUBIC achieving a lower
> congestion window in these cases with loss rates of 10^-2 and 10^-3?
>
> best,
> neal

I got a bounce from my "reply-all". It seems there was a typo in the
e-mail address of the report, and it should have been:
  Elliott Ecton <[e-mail]>
...rather than:
  Elliott Ecton <[e-mail]>

I am following up to make sure the [e-mail] address
has the reply and the thread has the correct e-mail address.

best,
neal