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Minutes Webex 11 April 2014, 6TiSCH WG

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. Alfredo Grieco
  4. Diego Dujovne
  5. Dominique Barthel
  6. Giuseppe Piro
  7. Guillaume Gaillard
  8. Kazushi Muraoka
  9. Maria Rita Palattella
  10. Michael Richardson
  11. Nicola Accettura
  12. Pat Kinney
  13. Patrick Wetterwald
  14. Pouria Zand
  15. Raghuram Sudhaakar
  16. Rouhollah Nabati
  17. Sedat Gormus
  18. Steve Simlo
  19. Xavi Vilajosana



Action Items

  • Pascal to call for CoAP draft WG adoption.
  • Maria Rita to check with Qin what she meant by "depends on implementation".
  • Thomas to discuss on ML exact wording of 6LoWPAN/RPL issues raised, then turn these points into tickets.
  • Thomas to start a thread on the ML about tracks


  • Administrivia [2min]
    • Approval agenda
    • Approval minutes last call
  • Update ad-hoc discussions [20min]
    • Security DT
    • 6top discussion
    • OTF discussion
    • 6LoWPAN/RPL
  • Terminology discussion [20min]
  • Tracks [15min]
    • tracks and queues
    • tracks and QoS
  • Next meetings [2min]
  • AOB [1min]


  • [08.05] Meeting starts
    • Recording starts
  • [08.06] Administrivia
    • Approval agenda

      No issues raised. Agenda approved.

    • Approval minutes last call

      No issues raised. Minutes last call approved.

    • Thomas encourages people to access Etherpad, or participate to note taking.
  • [08.07] Update ad-hoc discussions
    • Clean list of future/past meetings on bitbucket meetings wiki page, allows anyone to follow ad-hoc discussions.


    • [Thomas] Feedback on the new organization?
    • [Pascal] ad-hoc groups generate more information, this might require weekly 6TiSCH webex, so we can share that information. We will evaluate during a month and see.
    • [Pascal] 5 minutes is not much for all the slides we have.
    • Security DT
    • [08.11] 6top discussion [Xavi]
      • Qin could not attend, Xavi presenting.
      • 2 meetings
      • 1ast meeting on how to implement 6top negotiation, define how actions are represented as resources.
      • then realized that trying to do remote procedure call, actuate from one node on the schedule of another node.
      • group defined RPC using the YANG model. YANG allows definition of actions with input and output parameters, to be put in CoAP payload
      • Example: with CoAP/CBOR softcell reservation; response may be piggy-backed or delayed
      • Qin suggested defining a RPC CoAP method, ML discussion did not support the idea, POST is proposed method
      • Open Questions:
        • will CoAP observe be needed?
        • will CoAP block be needed?
      • [Pascal] Ask WG whether we adopt the CoAP document as WG document?
      • [Thomas] Should we ask for reviews first?
      • [Pascal] -00 doesn't have to be perfect. Not last call, just WG agrees that it's important work. Biggest thing is whether

        Action item: Pascal to call for CoAP draft WG adoption.

    • [08.21] OTF discussion
      • One call on 2 April 2014
      • Intro by Diego:
      • Latest update on draft (Maria Rita)
        • Worked on draft, updated sections related to basic commands create and delete softcell
        • Clarififaction needed to create ande change bundles. Draft visible on repo.
        • a bundle is associated to a track, so the softcell is associated to track
        • these commands are both used for creating bundles and for increasing a bundle in addition to reserving a soft cell
        • OTF will specify the track the cell it belongs to. Do not agree whether they should use a single track (best effort) or multiple tracks
        • READ.cell command may be used by OTF to get status information of the network. OTF should not use the READ.cell according to Maria Rita.

          Action item: Maria Rita to check with Qin what she meant by "depends on implementation".

        • CellList, Not clear how OTF can use it.
        • Neighbor list. Per neighbor statistics: does it mean tht all cells reserved with that neighbor?
        • OTF does not perform the allocation if the monitoring function is activated. What is the impact of monitoring function?
        • Over-provisioning handled by 6top should not collide with OTF.
        • If quality drops, OTF needs to make request to 6top, which coodinates negotiation
        • 6top actuation: Can OTF provide a policy for generating CREATE/DELETE soft cells?
        • [Xavi] At next OTF call, you might want to invite Xavi and Qin
        • [Maria Rita] Agreed
      • [08.33] Update on OTF event (Alfredo)
      • which events should OTF be dealing with?
      • OTF should keep track of tracks and bundles. In case of bundle saturation, OTF needs to ask 6top for bandwidth increase.
        • defining from a functional perspective the concepts such as Bundle, track, allocate cell, etc...
        • OTF should react according to status from 6top.
        • Work on OTF by Alfredo is to define the concepts with a functional perspective, so this can be used as a tool to define other mechanisms.
        • Not limited to OTF only, letting it open.
        • [Thomas] is this methodology/functional approach going to be part of the next draft?
        • [Alfredo] Yes, this will be in a dedicated section.
      • [08:37] Allocation policies (Nicola)
        • introduces variables (thresholds) to add a hysteresis algoright which satisfies a formula.
        • Post-allocation has threshold fixed to 0.
        • Replaces the terms pre- and post-allocation.
        • The objective is to introduce hysteresis (variables) to give more flexibility (elasticity) to the allocation.
    • [08:41] 6LoWPAN/RPL update (Pascal)
      • Presented flows at IETF89 plugfest and since the on 6TiSCH webex calls
      • RPL an 6LoWPAN evolved, now the architectures need to be optimized: cherry-pick components of both frameworks and put them together.
      • Several meetings with ROLL and 6lo chairs
      • A design team will not be created but instead individual calls will be done including relevant people at each field.
      • Items are:
        • support ND-only RPL leaves?
        • optimize the use of RA from RPL routers
        • optimize the frequency of NUD from RPL routers
        • Use target in efficient NS/NA
        • RPL's own DAD?
        • RFC6282 unclear on hop-by-hop headers.
        • Use flow labels. Improve encapsulation.
      • Interactions with to 6lo and 6man
    • Track with issues in the architecture draft repo this items.
    • Action item: Thomas to discuss on ML exact wording of 6LoWPAN/RPL issues raised, then turn these points into tickets.
  • [08.50] Terminology discussion
    • Pascal presents quickly a brief overview of the CDU matrix
    • bundles come by two. Incoming and outgoing. A L3 bundle is analogous to a link.
    • [Patrick] we need to converge on what we want to do, then we refine the text in the terminology. Try to find what is not clear. This discussion is to make sure we have a common understanding.
    • [Patrick] can work with Pascal and MR on the terminology.
    • [Maria Rita] agreed, multiple concepts need to be clarified
    • [Thomas] we are very active, with many calls and lots of things happening in the ML. We need a balance better between adding/developing new elements, and going back and consolidating what we have. Some of the drafts will need to consolidate its content and homogenize the concepts. We need to do this before IETF90 Toronto, including consolidating the use of terminology at each draft.
    • [Pascal] we could add a tag to each e-mail thread name according to its topic that is sent to the ML. For example [6top:],[otf:],[terminology:]
  • [09.02] Tracks
    • [Pascal] Out of time.

      Action item: Thomas to start a thread on the ML about tracks.

  • [09.04] Next meetings
    • Monday 4/14, 8-9am PDT
      • Security DT
    • Tuesday 4/15, 8-9pm PDT
      • 6top discussion
    • dat/time TBD
      • OTF discussion
    • Friday 4/25, 8-9am PDT
      • 6TiSCH webex
  • [09.04] AOB
    • Thomas on 4 week sabatical starting 19 April.
  • [09.05] Meeting ends