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Minutes Webex 20 September 2013, 6TiSCH group

Note: timestamps in PDT.

Taking notes (using Etherpad)

  1. Xavi Vilajosana
  2. Thomas Watteyne

Present (alphabetically)

  1. Thomas Watteyne
  2. Pascal Thubert
  3. Alaeddine Weslati
  4. Geraldine Texier
  5. Guillaume Gaillard
  6. Ken Bannister
  7. Maria Rita Palattella
  8. Nicola Accettura
  9. Pouria Zand
  10. Qin Wang
  11. Raghuram Sudhaakar
  12. Tina Tsou
  13. Tom Phinney
  14. Xavi Vilajosana




  • Administrivia [4min]
    • Approval agenda
    • Approval minutes last call
    • WG news
  • Preparing for Vancouver [10min]
  • Updates to "minimal" draft [10min]
  • Need for hysteresis in using RPL OF0 [15min]
    • RFC6719
  • Scoping of Work Item 2 [20min]
    • Examples report traffic
    • Ideas for scope and discussion
  • AOB [1min]


  • [08.05] Meeting starts
    • [Thomas] The group is at an interesting point. We have had many discussions. With 6 weeks left before Vancouver, good time to consolidate discussions in drafts.
  • [08.05] Administrivia [4min]
    • Approval agenda

      Xavi proposes to move his presentation on draft minimal at the end if time permits, or to next week. Change accepted.

    • Approval minutes last call

      No concerns raised on the call. Minutes approved.

    • WG news
      • Charting process in "External review" step. Scheduled for discussion by IESG on 09/26/2013 telechat.
      • Requested a 90min meeting slot during IETF 88 in Vancouver.
  • [08.10] Preparing for Vancouver [10min]
    • 6 weeks left to IETF 88
    • Main objective for Vancouver: have documents ready for WG adoption
      • Charter items: minimal, architecture, models
      • Others (TSCH, terminlogy)
      • Show activity on other drafts (security, 6top)
      • [Pascal] Volunteers for information and data models draft(s)?
      • [Qin] Difference between information and data model?
      • [Pascal] See "Information model" is abstract description of interactinos, "data model" is very concrete (bits-and-bytes).

        Raghuram and Pouria volunteer. Xavi happy to help review, but not author. Thomas happy to help define problems statement and follow process, but not author.

      • [Pascal] Thanks. You will need to elect one editor.
    • Second objective for Vancouver: informal interop and mini-demo
      • Objectives
        • informal
        • show implementations related to 6TiSCH
        • discuss implementation details
        • at the very best, show some interop of different implementations of the minimal draft
      • We might need to ask for a room?
      • [Thomas] It would be good to document goals and methods in a "implementers guide" draft.

        Xavi volunteers to participate.

      • [Pascal] Interop or demo? We might want invite IAB members to come take a look.
      • [Thomas] This is very early on, so let's not announce it as an official interop.
  • Updates to "minimal" draft [10min]

    Pushed to end of call, or next week.

  • Need for hysteresis in using RPL OF0 [15min]
    • See
    • Requirement of pass a value boundary on rank in order to change parent (to avoid Hysteresis)
    • Experiment with other techniques:
      • stability counter.
      • delta threshold.
    • [Xavi] Should we add this to the minimal draft?
    • [Pascal] We could keep RFC6719 in minimal, use experiment to decide on hysteresis, and maybe push to ROLL in the future
    • [Pascal] Per the charter, at the end, our interest is to produce a recommendation
  • [08.34] Scoping of Work Item 2 [20min]
    • Intro [Thomas]
      • Thanks to volunteers to contribute to document
      • We need to scope work item 2 clearly. FYI, charter states:

        Produce an Information Model containing the management requirements of a 6TiSCH node. This includes describing how an entity can manage the TSCH schedule on a 6TiSCH node, and query timeslot information from that node. A data model mapping for an existing protocol (such as Concise Binary Object Representation (CBOR) over the Constrained Application Protocol (CoAP)) will be provided.

      • Start with presentationof example report flows by Pouria, followed by discussion
    • Examples report traffic [Pouria]
      • Pouria presents report traffic flow examples
      • ISA100.11a
        • Services to read/write/execute
        • interesting objects: candidates, neighbors, neighborDiag, channelDiag, alertPolicy
      • WirelessHART
        • metrics: device, neighbor, signal levels
    • Discussion/Questions
      • [Xavi] Do we want to focus our work in the same way as ISA/WirelessHART which is closed and restricted to a set of parameters, or rather go to a more open mechanism.
      • [Thomas] +1. Our goal is not to replicate ISA/WirelessHART. Information Pouria presented is an example, we want to make sure the mechanism we design support this type of interaction. We're looking for "outlier" type of interaction the CoAP-based solution we are designing might not cover.
      • [Thomas] Pouria, from this exercise, have you seen any type of interaction that CoAP might not be able to deal with?
      • [Pouria] A priori, it seems feasible to use CoAP. Although we need a more detailed investigation on CoAP.
      • [Raghuram] Extensibility is important, we need to come up with just the base of of commands and functionality we need, and allow for extensions.
      • [Qin] Clarifying question: Pouria's presentation did not touch on action and request flows. Do those not exist?
      • [Pouria] The application layer services include "execute", which can be mapped to the action flow we identified.
      • [Thomas] Let's not forget the decentralized case.
    • toward CoAP mapping [Thomas]
      • Important questions to answer for work item 2. CoAP related. These are just examples, but something like that could be answered by work item 2 draft.
      • What is the URI scheme going to look like?
        • possible example: coap://6t/ to access 6TiSCH resource
      • How to map methods?
        • possible example: PUT coap://6t/c/ to add a cell
      • How to allow extensions?
        • possible example: use profiles. GET coap://6t/p/ to access list
  • [09.07] AOB [1min]

    Qin and Maria Rita volunteer to contribute to the information model as well.

  • [09.08] Meeting ends