Subject: [tcpm] Spencer Dawkins' Yes on draft-ietf-tcpm-cubic-06: (with COMMENT)

From: Spencer Dawkins <[email-masked]>
Date: Tue, 10 Oct 2017 21:30:43 -0700

Spencer Dawkins has entered the following ballot position for
draft-ietf-tcpm-cubic-06: Yes

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COMMENT:
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I'm really glad to see this specification entering IESG Evaluation.

I have a few comments, but most are editorial or (at most) about improving
clarity.

In this text,

   In a smaller BDP network where Standard TCP flows are
   working well, the absolute amount of the window decrease at a loss
   event is always smaller because of the multiplicative decrease.

I got lost on "always smaller" than what - than Standard TCP? Or CUBIC? Or
something else?

Nit: Is "weithed" "weighted", or is it something else?

In 4.7.  Timeout

   In case of timeout, CUBIC follows the standard TCP to reduce cwnd,
   but sets ssthresh using beta_cubic (same as in Section 4.5).

should "standard TCP" be "Standard TCP"? I wasn't watching for other
occurrences of "standard TCP", but I noticed a bunch of them.

In this text,

  CUBIC MUST employ a slow start algorithm, when the cwnd is no more
   than ssthresh.  Among the slow start algorithms, CUBIC MAY choose the
   standard TCP slow start [RFC5681] in general networks, or the limited
   slow start [RFC3742] or hybrid slow start [HR08] for high-bandwidth
   and long-distance networks.

is there any guidance you can give implementers about when to choose specific
slow start algorithms?

In 5.10.  Incremental Deployment

   CUBIC requires only the change of TCP senders, and does not require
   any assistant of routers.

I'm not parsing the sentence. Is it saying

   CUBIC requires only changes to TCP senders, and does not require
   any changes to routers.

? Either way, it might be worth pointing out here that no changes to TCP
receivers are required, either.