Subject: [aqm] Suresh Krishnan's No Objection on draft-ietf-aqm-pie-07: (with COMMENT)

From: "Suresh Krishnan" <[email-masked]>
Date: Wed, 18 May 2016 17:46:37 -0700

Suresh Krishnan has entered the following ballot position for
draft-ietf-aqm-pie-07: No Objection

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COMMENT:
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Section 4.1:
QDELAY_REF is used here without definition. Suggest something like:

s/is smaller than half of QDELAY_REF/is smaller than half of the
target delay value (QDELAY_REF)/

Section 4.2:

Not sure what this piece of pseudo-code intends to achieve. Isn't this a
no-op?

        } else {
            p = p;
        }

Section 5.3:

What does the following text intend to say? Do you mean when it is turned
off?

"When PIE is optionally turned on and off, ..."

Section 5.4:

The forced drop at 8.5/PIE->drop_prob_ packets is not consistent
with the pseudo-code in page 24. The drop_early() does not the
drop packets if the queue is not congested. Either the
pseudo-code or text in this section needs to be adjusted.

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From: "Rong Pan (ropan)" <[email-masked]>
Date: Tue, 24 May 2016 00:28:43 +0000

Done.

>Not sure what this piece of pseudo-code intends to achieve. Isn't this a

It is a no-op. At least this covers all the cases, less chance to make
mistakes :-).

>"When PIE is optionally turned on and off, ..."

How about ³PIE can automatically turn on and off"?

>pseudo-code or text in this section needs to be adjusted.

If a queue is not congested, we don¹t drop packets. I added comments in
Section 5.4
to be clear.

Thanks,

Rong

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From: Suresh Krishnan <[email-masked]>
Date: Tue, 24 May 2016 14:40:21 +0000

Hi Rong,
  Sounds good. All your proposed changes look good but one. Please see inline.

> How about ³PIE can automatically turn on and off"?

Not sure if this new text will make it any clearer. I was guessing more "When
PIE is turned off,..." but was not sure. Does that make sense to you?

Thanks
Suresh

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From: "Rong Pan (ropan)" <[email-masked]>
Date: Tue, 24 May 2016 22:46:21 +0000

To be consistent with the pseudo code and avoids the confusion of "turning
on/off".
How about we retitle it to “Setting PIE inactive”

-Rong

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5.3 Setting PIE active and inactive

Traffic naturally fluctuates in a network. It would be preferable not to
unnecessarily drop packets due to a spurious uptick in queueing latency.
PIE has an optional feature of automatically turning active/inactive.
To implement this feature,
PIE SHOULD only become active when the buffer occupancy is over a certain
threshold, which SHOULD be set to 1/3 of the tail drop threshold.
PIE SHOULD become inactive when congestion is over, i.e.
when the drop probability reaches 0, current and previous delay samples
are all below half of QDELAY_REF.

---

From: Suresh Krishnan <[email-masked]>
Date: Thu, 26 May 2016 03:10:10 +0000

Hi Rong,

> How about we retitle it to “Setting PIE inactive”

Yep. Works for me.

Thanks
Suresh