[6tsch] minutes webex 30 August 2013

[Thomas Watteyne <[e-mail]>]

All,

You will find the minutes of today's webex below.

FYI, all the minutes and slides are archived a
https://bitbucket.org/6tsch/meetings/.

Thanks to Xavi and Dominique for taking notes!

As usual, fix anything we might have missed directly in the e-mail and
reply. We will approve and adopt the minutes at the next call.

Thomas

---

Minutes Webex 30 August 2013, 6TiSCH group

Note: timestamps in PDT.
Taking notes *(using Etherpad)*

   1. Xavi Vilajosana
   2. Dominique Barthel
   3. Thomas Watteyne

Present *(alphabetically)*

   1. Alfredo Grieco
   2. Diego Dujovne
   3. Dominique Barthel
   4. Geraldine Texier
   5. Laurent Toutain
   6. Maria Rita Palattella
   7. Oliver Hahm
   8. Pascal Thubert
   9. Patrick Wetterwald
   10. Pieter de Mil
   11. Pouria Zand
   12. Qin Wang
   13. Raghuram Sudhaakar
   14. Tina Tsou
   15. Thomas Watteyne
   16. Xavi Vilajosana
   17. Xavier Lagrange

Recording

   - Webex recording (audio+slides,streaming)
   -
   https://cisco.webex.com/ciscosales/lsr.php?AT=pb&amp;SP=MC&amp;rID=71053472&amp;rKey=9829fc81dd628028<https://cisco.webex.com/ciscosales/lsr.php?AT=pb&SP=MC&rID=71053472&rKey=9829fc81dd628028>
    *[63min]*

Slides

   - slides_130830_webex.ppt<https://bitbucket.org/6tsch/meetings/src/master/130830_webex/slides_130830_webex.ppt>:
   slides shared during the call

Agenda

   - Administrivia *[4min]*
      - Agenda bashing
      - Approval minutes
      - Charter submitted
      - IETF MLs down 3pm-12am 08/28
      - Vancouver: Hyatt hotel registration link
      - Logo update
   - Flow Identification *[20min]*
      - 4 flows?
      - how to trigger a schedule update?
      - confirmation message?
   - Network bootstrapping *[20min]*
      - Synchronization and neighbor discovery *[Pouria]*
      - Time parent selection and EB priority *[Xavi]*
      - Impact of routing loops on synchronization? *[Pascal]*
   - Fast Join/Synchronization *[Alfredo, 10min]*
   - AOB *[1min]*

Minutes

   - *[08.04]* Meeting starts
   - *[08.04]* Administrivia
      - Agenda bashing

      No issues raised. Agenda approved.

      - Approval minutes last call.

      No issues raised. Minutes approved.

      - Charter submitted
         - Adopted name 6TiSCH.
         - Charter submitted. No answer yet.
      - Loss of e-mail in all IETF mailing list on Wed 08/28 3pm-12am
      midnight PDT.

      Action item: [all] verify outbox and resend any email not in the ML
      archives (
      http://www.ietf.org/mail-archive/web/6tsch/current/maillist.html)

      - Vancouver:
         - Hotel eservation can be done by web at
         https://resweb.passkey.com/go/ietf88.
      - Logo update

      Action item: [Xavi] to redo logo.

      - *[08.10]* Flow Identification
      - 4 flows?
         - Flow between and ME and nodes and vice-versa
         - ME is the service that manages the schedule.
         - 4 flows:
            - Action
            - Query
               - Not clear what we want to ask for an specific cell.
               - READ.cell: what are the attributes to query? Information
               about the usage of the cell?
               - Information should be configurable.
            - Report
            - Event
         - *[Thomas]* Simplification: Report and Query have common
         elements. For common elements, instead of a query, we could
add an action
         which triggers a report.
         - *[Xavi]* Do we need to define everything or define basic
         elements of Query Flow and provide TLV for more specific elements
         - *[Pascal]* +1. Very common the standards
         - *[Thomas]* +1. Anybody disagrees?

         No issue raised on the call.

         - how to trigger a schedule update?
         - Event Flow: what do we consider as an event. How to trigger a
         schedule update?
         - Part of event flow.
         - 5th request flow: enable a transport mechanism to transport the
         request to the ME.

         Action item: [Pascal] To start a thread on the ML to answer
         whether we want a 5th flow or not.

         - confirmation message?
         - When a node sends a Requests to the ME, how does it know that it
         arrived?
         - Options:
            - Do nothing (best effort)
            - Rely on Transport e.g CoAp and Confirmable msg
            - App-Level ACk
            - Use another flow (e.g action flow)
         - *[Maria Rita]* Let's be cautious not to make things too
         complicated.

         Action item: [Qin] to continue discussion on the ML.

         - *[08.35]* Network bootstrapping
      - Synchronization and neighbor discovery
         - *Pouria* presents his slide with sequence of echanges between
         layers and nodes.

         Note: slides taken from
         http://www.ietf.org/mail-archive/web/6tsch/current/msg01156.html.

         - Temporary time parent selected among neighbors heard. Then, when
         RPL selects the best parent, may change time source to be the
RPL parent.
         - *[Pascal]*
            - is it possible that we have multiple instances of RPL and the
            management of multiple different RPL instances and time
sources might be
            complicated as some of the time sources might not be in
all RPL instances.
            - A node might belong to multiple instances of RPL, you can
            listen to other parents in different RPL instances.
            - How to signal or enforce that a RPL instance is for
            synchronization because there is a node with GPS?
            - With multiple instances only one is used for synchronization.
         - *[Thomas]* What characteristics do we want the the
         synchronization RPL instance to have?
         - *[Pascal]* 3rd RPL model: multiple roots, on DODAG. If you want
         to send data to the roots, you need them to be grounded.
         - *[Raghuram]* Why couple RPL routing parents with TSCH time
         source neighbor? Might be a layer violation.
         - *[Pascal]* only using info opaque information from the other
         layer
         - *[Pascal]* We benefit from the loop-free nature of the RPL DAG.
         - *[Alfredo]* If we have a many neighbor nodes that send the EBs
         for synchronization, this goes in many different channels, to
deal with
         that we can have some coordination to select the right parent to join.
         Would that not be on the direction of having a RPL instance for
         Synchronization?

         Action item: [Thomas]: to start a thread on the ML about that
         topic.

         - *[08.58]* Fast Join/Synchronization
      - Ideas about fast join synch on TSCH
      - When a node joins a network, it needs to wait for the EB. During
      this time, the radio is on and spends energy. Also this can take
some time
      as the CH sequence is not known in advance.
      - After node joins, synchronization is kept with KA, EBs...
      - Average Join Time: depends on many parameters (number of channels,
      Ch. Avg time between EBs amongst neighbors, etc)
      - Assumptions:
         - one synchronizer node exists.
         - this node is powered with the mains. (no battery powered).
         Realistic assumption.
         - A node that is synchronized sends EB every M slotframes.
         - See plots in the slides.
         - Issues:
            - How many EBs should the synchronized node send?
            - How to choose the slotframe cell?
            - Detect end of bootstrap phase.
         - *[Thomas]* this might be useful both for synchronization and for
      the continuous neighbor discover once all nodes have joined.
      - *[Alfredo]* Agreed.
   - *[09.06]* AOB

   No other business is brought up.

   - *[09.07]* Meeting ends