Re: [Last-Call] Last Call: <draft-ietf-quic-recovery-32.txt> (QUIC Loss Detection and Congestion Control) to Proposed Standard

[Yoshifumi Nishida <[e-mail]>]

Hi Gorry,

On Sat, Oct 24, 2020 at 4:36 AM Gorry Fairhurst <[e-mail]>
wrote:

>
> So I reviewed this ID several times in the WG. At the WGLC, I had no
> substantive issues, and I see quite a lot of change since WGLC (most
> really good!).
>
> However, I also something I hadn't expected and that since rev -30, this
> has introduced the option to use PRR:
>
> ..."Implementations MAY reduce the congestion window immediately upon
>          entering a recovery period or use other mechanisms, such as
>          Proportional Rate Reduction ([PRR]), to reduce the congestion
> window
>          more gradually."
>
> This did surprise me, but perhaps the working group thinks this is Reno
> behaviour?
>

This seems to be ok to me as QUIC's CC already deviates from Reno in
various points and the doc just says "similar to Reno".
Another point is this part is not mandatory.

Since PRR doesn't change the window size after recovery, the deviation
looks minor from my point of view.
As long as the algorithm reduces the congestion window properly (be close
to ssthresh at the end of recovery), I think it won't be aggressive.

Thanks,
--
Yoshi