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Minutes Webex 4 October 2013, 6TiSCH group

Note: timestamps in PDT.

Taking notes (using Etherpad)

  1. Xavi Vilajosana
  2. Pascal Thubert
  3. Thomas Watteyne

Present (alphabetically)

  1. Thomas Watteyne
  2. Pascal Thubert
  3. Diego Dujovne
  4. Geraldine Texier
  5. Guillaume Gaillard
  6. Ken Bannister
  7. Maria Rita Palattella
  8. Nicola Accettura
  9. Patrick Wetterwald
  10. Pouria Zand
  11. Qin Wang
  12. R. Nabati
  13. Raghuram Sudhaakar
  14. Tom Phinney
  15. Xavi Vilajosana




  • Administrivia [3min]
    • Approval agenda
    • Approval minutes last call
    • IETF88: preliminary agenda
  • minimal draft [5min]
    • join priority width
    • comments/changes
  • update models draft [35min]
    • summary Tuesday discussion
    • proposed ToC
      • separate payload format from CoAP resource mapping?
    • 6lo thread on monitoring
      • "[6lo] [coman] WG Review: IPv6 over Networks of Resource-constrained Nodes (6lo)"
      • information model in English, turned into YANG?
    • communication paradigms
      • 5-6 communication paradigms in architecture draft?
      • terminology: interaction model and communication paradigm
  • On-the-fly scheduling [15min]
    • overview
    • discussion
      • implementation
      • hysteresis
      • TASA
      • queue size vs. bundle usage
      • bit
      • separating algorithm from mechanism
    • goals and next steps?
  • AOB [2min]


  • [08.04] Meeting starts
  • [08.05] Administrivia
    • Approval agenda

      No issues raised. Agenda approved.

    • Approval minutes last call

      No issues raised. Minutes approved.

    • IETF88: preliminary agenda
      • IETF preliminary agenda has been delayed 1 day. Should appear today at
      • Until Monday to request a change in meeting schedule (hopefully don't need to).
      • Final agenda published 11 October.
      • Cut-off date for draft submission (including -00) is 21 October.
  • minimal draft
    • join priority width
      • range of join priority is defined as 0x3f
      • answer from IEEE802.15.4e editor is that 0x3f might be an error and the byte is intended to be used as a complete byte.
      • this most probably means that using 0x00-0xff as the range (rather than 0x00-0x3f) is OK.
      • [Qin] This is good news.
    • comments/changes
      • Thanks to Xavi for incorporating all the changes!
      • [Xavi] Will incorporate Maria Rita's comments today.
  • update models draft
    • summary Tuesday discussion [Raghuram]
    • discuss contents of the data model draft
    • great input (including from Dan Romascanu) on how we can be consistent with the terminology to fit a data model as RFC3444 defines.
    • include:
      • naming convention to URI
      • mapping of URI to 6top resources
      • Message formats
      • Extensible resources
        • profile based definition?
        • how do we discover the profile, i.e. what messages will be exchange for that discovery methods?
        • custom uri to send back messages when event is detected
        • profile based definitions
        • including set of extensible resources e.g. PCE could install a profile that it needs for its computation
    • Raghuram to push current version on bitbucket repository today.
    • see
    • Discussion
      • [Xavi] The data model should be reused. Draft seems to bind it with CoAP. Should be separated for use e.g. by RSVP to be described in another draft?
      • [Raghuram] agreed. But there is limited time.
      • [Pascal] why is the content so tightly bound to CoAP?
      • [Raghuram] define the data model to be reusable in different transport.
      • [Pouria] presents 6TiSCH MIB.
      • [Qin] Indicate for fields that can be read what observable trigger can be used.
      • [Thomas] Are there any fields which can be read for not observed?
      • [Qin] Having that option might enable a better handling of registration to observe, triggers, etc.
    • 6lo thread on monitoring
      • [Thomas] 6lo discusses the proposed charter of 6lo. Related MIB modules, they are looking for a way to monitor the state of a 6lo/6LowPAN network.
      • Encourage editors of this draft to follow the 6lo discussion.
      • [Thomas] Clarifying question: NVP vs TLV?
      • [Raghuram] Name Value Pair: human readable ASCII format.
    • communication paradigms [Pascal]
      • ISA100 has 3 comm paradigms.
        • client/server
        • pub/sub
        • source/sink
      • abstract concept.
        • [Tom] based on IEC61158
      • we have similar approach, but more options
        • point to point model (CoAP REST model)
        • At L3, multihop along track (RSVP-like)
        • At l2, single hop (6top)
      • Mapping of comm paradigm to protocol:
        • [Thomas] why SNMP?
        • [Pascal] way to implement Client/server. Just examples of protocols that can be used to implement the communication paradigms.
      • what document is the right place:
        • informational model: high level overview.
        • data model: YANG seems the direction to define the data model.
        • implement the data model in different data formats (CBOR, NVP, TLV, etc.)
        • data and command do not need to be tightly bound.
      • [Raghuram] in terms of CoAP cannot separate payload than URI and method, so the implementation is tight to the communication model.
      • [Thomas] do not see source/sink model as needed per-see. CoAP provides the observe and notifications.
      • [Tom] Source/sink is a application communication paradigm and there is no reason that it needs to be modelled that way in the communication layers. Most people end up with wireless running alerts to a single device (e.g. gateway, BBR). n-to-1 at the low layers. Source/sink applies to the application, and how you model it in the lower layers is really the responsibility of the implementers.
  • [08.56] on-the-fly scheduling
    • overview [Diego]
      • Idea is to adapt the number of cells according to the traffic constrains (queue size, etc.) on the fly.
      • This is a distributed approach.
    • discussion
      • implementation
        • run on top of 6top
        • define statistics and interface, algorithm is independent
      • hysteresis
        • map queue sizes to link requirements.
        • reaction time to avoid hysteresis
        • handle collisions with other neighbors scheduling same cell (not a global picture)
      • TASA
        • Distributed TASA?
      • IPR Cisco:
        • [Diego] what is covered?
        • [Pascal] Ciscp IPR does not matter as it covers many aspects, also in RPL.
        • [Pascal] Mentioning the IPR is mandatory, mentioned it in ML for that reason.
    • goals and next steps?
      • [Thomas] Good exercise to detect missing aspects on 6top as it is a use case on top of 6top.
      • [Diego] Yes, will do.
  • [09.07] AOB

    No other business raised.

  • [09.08] Meeting ends