Hi Thomas,

thanks for your comments I confirm I will attend the meeting this
afternoon. I will go through your reviews carefully.

thanks so much!
X

2016-09-23 11:44 GMT+02:00 Thomas Watteyne <[email protected]>:

> All,
>
> In preparation of the 6TiSCH interim meeting later today, below is my
> review of draft-ietf-6tisch-6top-sf0-01. I'm reading the XML file
> directly at https://bitbucket.org/6tisch/draft-ietf-6tisch-6top-
> sf0/src/master/draft-ietf-6tisch-6top-sf0-02.xml, to be most up-to-date.
>
> *@authors*, could you confirm you will attend the 6TiSCH interim meeting
> later today?
>
> Thomas
>
> *issue tracking*
>
> This is now a WG doc. Per the 6TiSCH best practice, this means issues
> should be tracked by https://trac.tools.ietf.org/wg/6tisch/trac/report/1
>
> *@editor*, please:
> - report the open issue on the bitbucket issue tracker into the IETF
> 6TiSCH issue tracker
> - disable the bitbucket issue tracker
>
> *organization*
>
> The idea is that the definition of an SF follows the recommendations from
> https://tools.ietf.org/html/draft-ietf-6tisch-6top-protocol-02#section-5,
> in particular answers all the requirements and follows the structure.
>
> *@editor*, please add an appendix at the draft to indicate whether you
> answer all requirements (checklist) and formatting. You can mark this
> appendix a temporary by putting the "[temporay]" keyword. One example is
> https://tools.ietf.org/html/draft-ietf-6tisch-6top-protocol-02#appendix-A.
>
> *implementation/.performance evaluation*
>
> The WG needs to know (1) who implemented this and (2) how good the
> proposed solution performes.
>
> *@editor*, follow the implementation section by a "Performance
> Evaluation" section in which you list the key results. The WG needs to know
> the limits of the SF: how does it scale with number of motes, network
> dynamics, etc.
>
> *figure*
>
> *@editor*, as discussed in IETF96 Berlin, Figure "The SF0 Allocation
> Policy" is not clear. Please comment on the changes you agreed to do.
>
> *general confusion about cells/bandwidth*
>
> I fail to understand the relationship between cells and bandwidth. You
> express bandwidth in kbps, but a cell carries one packet, and that packet
> can contain ~0-100 bytes of payload. Many small packets is very different
> from a few large packets from a scheduling point of view.
>
> I therefore STRONGLY suggest to think about number of packets, no kbps.
>
> *general questions about PDR*
>
> I'm not at all convinced about using PDR to calculate the number of cells,
> based on a number of kbps. It's unbelievably complex for no reason.
>
> Rather, I suggest to think only about number of cells used: if I'm using
> 90% (resp. add) of the outgoing cells to a particular neighbor over some
> period of time, I should probably add (resp. delete) some.
>
> *about timeout*
>
> The draft now says
>
> "The general timeout equals the equivalent time of the number of slots
> until the next scheduled cell."
>
> Next scheduled cell to whom? In RX or TX? What are retries?
>
> Similarly, "Node Behavior at Boot" states that the "timeout" is calculated
> as:
>
> timeout = (2^(macMaxBE+1)-2^macMinBE) * SM
>
> - what timeout is this exactly?
> - minimal Slotframe, SM: is that a duration, a number of slots?
> - what is the unit of timeout?
>
> *metadata*
>
> I don't understand the use of the metadata in Section "Meaning of Metadata
> Information".
>
> *PDR threshold*
>
> "Relocating Cells" now states:
>
> SF0 uses Packet Delivery Rate (PDR) statistics to monitor the currently
> allocated cells for cell re-allocation (by changing their slotOffset and/or
> channelOffset) when it finds out that the PDR of one or more softcells
> below 20% of the average PDR.
>
> The average PDR of what? Why 20%?
>
> *editorial suggestions*
>
> - the many acronyms (BEA, COBU, NIBR,NOB, AP, etc) add confusion more than
> clarity. THere appears to be a new term/acronym every 2 sentences! Can we
> not simply talk about "incoming", "outgoing" and "generated"? Not every
> word needs an acronym.
> - I don't understand what Whitelist and Blacklist mean in the "Rules for
> CellList" section.
> - "delete one or more cells" and "add one or more cells" is not precise
> enough. How many should be added/deleted?
> - the term bandwidth is confusing. Is it a number of packets per second?
> per frame? a number of cells? *@editor*, please add a definitions
> section, and consider changing the terminology.
> - isn't "NOB=NIBR-COBU", not "NOB=COBU+NIBR"
> - the draft starts very abruptly by referencing triggering events, BEA and
> allocation policy in the "Rules for Adding/Deleting Cells" Section. At that
> point of the draft, the reader has no idea what that is. *@editor*,
> please add an "Overview" section which contains a couple of paragraphs.
>
> *nits and typos*
>
> [use Ctrl+F]
>
> - "and determine" -> "and determines"
> - re-allocation-> relocation
> - dissappears -> disappears
> - 6P ALL Request -> 6P ADD Request?
>
> --
> _______________________________________
>
> Thomas Watteyne, PhD
> Research Scientist & Innovator, Inria
> Sr Networking Design Eng, Linear Tech
> Founder & co-lead, UC Berkeley OpenWSN
> Co-chair, IETF 6TiSCH
>
> www.thomaswatteyne.com
> _______________________________________
>
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>
>


-- 
Dr. Xavier Vilajosana Guillén­
Research Professor
Wireless Networks Research Group
Internet Interdisciplinary Institute (IN3)
Universitat Oberta de Catalunya­

+34 646 633 681| [email protected]­ | Skype­: xvilajosana
http://xvilajosana.org
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