Subject: [quicwg/base-drafts] Spin bit observers can't see the packet number anymore (#1936)

From: Brian Trammell <[email-masked]>
Date: Tue, 30 Oct 2018 21:14:02 +0000 (UTC)

@tfpauly pointed out that there was stale text in -01 that referred to an observer using the packet number to reject lost and reordered edges. Now that PNE is in, this is nonsensical. This PR removes it and points to heuristic methods instead.
You can view, comment on, or merge this pull request online at:

  https://github.com/quicwg/base-drafts/pull/1936

-- Commit Summary --

  * remove PN observation text

-- File Changes --

    M draft-ietf-quic-spin-exp.md (21)

-- Patch Links --

https://github.com/quicwg/base-drafts/pull/1936.patch
https://github.com/quicwg/base-drafts/pull/1936.diff

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From: Tommy Pauly <[email-masked]>
Date: Tue, 30 Oct 2018 15:25:41 -0700

tfpauly approved this pull request.

Looks good!

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From: mirjak <[email-masked]>
Date: Wed, 31 Oct 2018 09:15:22 -0700

mirjak commented on this pull request.

> @@ -224,11 +214,12 @@ small amount of periodic application traffic, where that period is longer than
 the RTT, measuring the spin bit provides information about the application
 period, not the network RTT.
 
-Simple heuristics based on the observed data rate per flow or changes in the
-RTT series can be used to reject bad RTT samples due to application or flow
-control limitation; for example, QoF {{TMA-QOF}} rejects component RTTs
-significantly higher than RTTs over the history of the flow. These heuristics
-may use the handshake RTT as an initial RTT estimate for a given flow.
+Simple heuristics based on the observed data rate per flow or changes in the RTT
+series can be used to reject bad RTT samples due to lost or reordered edges in
+the spin signal, as well as application or flow control limitation; for example,
+QoF {{TMA-QOF}} rejects component RTTs significantly higher than RTTs over the
+history of the flow. These heuristics may use the handshake RTT as an initial
+RTT estimate for a given flow.

I would be careful here because you actually want to detect suddent changes. The question is rather is it only one outlier or did actually something happen.

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From: mirjak <[email-masked]>
Date: Wed, 31 Oct 2018 09:15:54 -0700

mirjak approved this pull request.

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From: Brian Trammell <[email-masked]>
Date: Wed, 31 Oct 2018 16:37:14 +0000 (UTC)

britram commented on this pull request.

yep, but this is a common problem with any passive RTT scheme (or indeed, RTT estimation at an endpoint): the base data is noisy, so it takes a few samples to adjust to a new real value. 

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From: Brian Trammell <[email-masked]>
Date: Wed, 31 Oct 2018 09:37:47 -0700

Merged #1936 into master.

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