Subject: [Roll] TSV-DIR Review of draft-ietf-roll-trickle-05.txt

From: Martin Stiemerling <[email-masked]>
Date: Thu, 23 Dec 2010 10:50:54 +0000

Hi,

I've reviewed this document as part of the transport area
directorate's ongoing effort to review key IETF documents. These
comments were written primarily for the transport area directors, but
are copied to the document's authors for their information and to
allow them to address any issues raised. The authors should consider
this review together with any other last-call comments they
receive. Please always CC [email-masked] if you reply to or forward
this review.

Summary
This draft describes the trickle algorithm which allows to exchange information between nodes connected to a lossy shared medium. It defines no protocol usage of the algorithm, but let this to other drafts (e.g., roll-rpl).

The draft itself is well-written, including an easy to understand algorithm description, description of parameters, and description of limitations of the algorithm.

Transport Issues

- Section 4.2 How is the very initial value for I chosen?

- Section 5, 1st bullet: it correctly says "the default value of Imin is 4 times the worst case link layer latency". Should the protocol doc also indicate what the authors believe to be the worst case link layer latency? Otherwise the text might also be not that clear.

- Section 5, step 5 vs. step 3: step 3 says "transmits if" , but step 5 does never says in the text that something is transmitted if a "inconsistence" state is received. 

Others (nits)
- Section 4.1, 2nd bullet: the formula (log(max/min)) and the parameters can be improved in terms of saying what is actually what: There is no Imax/Imin in the formula. Imin is in time units, while Imax is a number without a unit? I guess the described value of 16 is actually not Imax, but the result of log(Imax/Imin). The text is somewhat confusing to me, even though I do understand the meaning of the text.

- Section 4.1, 3rd bullet: s/constant/constant k/ to be consistent with the other bullets

- Section 5, 1st bullet, last sentence "Worst case...", I can hardly read this sentence. Can you rephrase it?

With best regards

  Martin

[email-masked]

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