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Deterministic Networking (Active WG)
Rtg Area: Alvaro Retana, Alia Atlas, Deborah Brungard | 2015-Oct-05 —  
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IETF-99 detnet minutes

Session 2017-07-20 0930-1200: Congress Hall I - Audio stream - detnet chatroom

Minutes

minutes-99-detnet-00 minute



           DetNet Minutes IETF99 (Prague)
          >
          > Session 1:
          > THURSDAY, July 20, 2017
          > 0930-1200  Morning Session I
          > Congress Hall I
          >
          > Slides:       https://datatracker.ietf.org/meeting/99/session/detnet
          > Etherpad:
          http://etherpad.tools.ietf.org:9000/p/notes-ietf-99-detnet?useMonospaceFont=true
          
          > Meetecho:     http://www.meetecho.com/ietf99/detnet
          > Audio stream  http://ietf99streaming.dnsalias.net/ietf/ietf993.m3u
          > Jabber:  xmpp:detnet@jabber.ietf.org?join
          >
          > Available post session:
          > Recording:  https://www.ietf.org/audio/ietf99/
          > YouTube:    https://www.youtube.com/watch?v=rrqVLyJCfvk
          >
          > Num Start #Min Information
          > 0   9:30   10  Title:  Intro, WG Status, Draft Status
          >                Presenter:  Chairs
          Question for discussion by WG, ready for last call on Arch draft?
          Use Cases mature but no rush to close door, new use cases coming in,
          old ones still under discussion. At some point need to ship it. Not
          critical for near term. Once not rev'd for a while will call it done.
          Will do last call on (which one?)
          Completing dataplane alternatives is not too critical. It was helpful
          coming up with the dataplane solutions draft.
          Security draft on the agenda, would like to ask if ready for adoption.
          
          > 1   9:40   15  Title:  DetNet Architecture
          >                Presenter:  Norm Finn
          >                Draft:
          https://tools.ietf.org/html/draft-ietf-detnet-architecture-02
          
          No substantial change since March'17. Just clarifications etc.
          Arch doc - remove sec 5 on ideas that didn't make it. Then ask for WG
          last call.
          Everyone should look over it, meanwhile do removal as planned. If removed
          text is a problem, please propose text on how to resolve.
          Pascal Thubert: Wireless is experimental, too early to put in this draft,
          so not working on it
          Lou Berger: (poll)   How many have read this version: a good number
                  How many have read other versions: also a good number
          How many think ready for LC: also a reasonable number
          Lou Berger: Once planned update is publish will move towards last call,
          so please read and send comments and proposed text to the list.
          
          > 2   9:55   30  Title:  DetNet Data Plane Encapsulation
          >                Presenter:  Jouni Korhonen
          >                Draft:
          https://tools.ietf.org/html/draft-dt-detnet-dp-sol-01
          
          Stewart Bryant: Would be good if had a unified approach that could then
          be adapted to the underlay only once.
          Jouni Korhonen: Last time got feedback that encapsulation was nogo due
          to not being done that way before.
          Stewart Bryant: Will need more discussion, particularly if need new HW
          Lou Berger: Tradeoffs - I personally agree that it's unfortunate to not
          have a single encapsulation, but the elimination of PWs on end stations
          makes their stack support of DetNet easier.  I also agree that it needs
          to be consider further once WG document.
          Stewart Bryant: Look forward to have the discussion around adoption.
          Norm Finn: Much of the focus on the data plane docs has been on sequence
          number defined needed for PREF. Not necessary for hard partitioning
          (zero congestion, fix latency) doesn't need serialization. Maybe thus
          more flexible in terms of encapsulation? Some applications that don't
          need serialization might be easier.
          Stewart Bryant: Is simpler design that works for "most" applications
          better?
          Lou Berger: Separable between flow ID and encapsulation. Two building
          blocks.
          Greg Mirskey: Is PW an Ethernet PW? There are different types of PWs.
          Jouni Korhonen: Yes, typical Ethernet PW.
          Greg Mirskey: Usually no seq number in Ethernet PW? And many
          implementations don't even implement control word.
          Jouni Korhonen: Assume we always have a control word, if HW doesn't
          support it, too bad. If want PW device to be DetNet capable won't be
          available off the shelf, will need to adapt it. Thus we are brave enough
          to take this step.
          Lou Berger: Said another way if hardware doesn't support the protection
          function, serialization isn't need.
          Pat Thaler: Old HW won't support DetNet timing requirements, so probably
          can't do DetNet over old HW.  Also, it is important to support control
          work in general - w/o it can't distinguish bet IPv4 vs v6.
          Stewart Bryant: Old HW didn't support control word (CW) so would be new
          implementation. Encouraging people to put CW in for reasons suggested by
          Pat. Expect all new hardware to support the control work.  Sequence number
          is an option, but don't think any have implemented it.
          Pat Thaler: Packet Replication and Elimination Function (PREF) has been
          part of DetNet since the start.  It is necessary for some of the use
          cases and requires serial numbers.
          Norm Finn: The detnet goal is to do PREF, need serial #. The goal of
          DetNet is not PWs. PW was handy place to find serial numbers. IF some
          don't do
          Lou Berger: This is a good point.  We have a requirement to define
          a function, not use PWs.  If WG decides on a different path, e.g.,
          EPVN-based encapsulation, than this is a fine direction if this is WG
          consensus.
          Jeff Tantsura: Must reference different draft (EVPN VPWS). Also control
          word not mandatory, used if not entropy label (?). May consider making
          it required.
          Lou Berger: this is good feedback for WG adoption.
          Deborah Brungard: Speaking as AD, use of control word is fine for this
          new functionality. PALS will have strong statement about bad things if
          no control word, so can expect to have control word.  There is concern
          on the design team work, it's time to being this work to the WG and
          consider it or individual drafts. Need to go forward.
          Lou Berger:  This is a good point, there are no other contributions for
          DetNet data plane.  If hashing out solutions, we should do this in the
          context of a WG document.
          Jouni Korhonen:  DT doesn't want to continue as DT, ready to move to
          adoption and see if serves as solid base for further work.
          Lou Berger: Remember, adoption doesn't say this will be RFC, says this
          is what WG will start with.
          Greg Mirsky: Doesn't adoption mean that we've agreed with the technical
          solution. If don't feel e.g. PW is correct technical solution, do
          we adopt?  What does adoption say?
          Lou Berger: It says this is the starting point for the documented WG
          solution. Again, we don't have alternative documents to start so there
          is no choice.
          Stewart Bryant: Invitation for alternative proposals
          Lou Berger: Yes, this invitation has always been open.
          Stewart Bryant: Need open discussion not closed meetings with reporting.
          Lou Berger: DT archives open. Can discuss any document on mailing list.
          Eric Gray: In most WGs once DT has been appointed, worthless effort to
          do alternative designs.
          Lou Berger: But individuals can always produce individual draft, will
          be considered/integrated.
          Eric Gray: This isn't the case in many WG.
          : we've seen this happen in other WGs
          Jouni Korhonen:  can we move forward?
          Shahram Davari: If objection for PW is that CW not used. The RFC has
          control word. Objective is minimum change in standards. Don't need to
          create new standard.
          
          Lou Berger: Do you need control word if don't care about protection
          function?
          Jouni Korhonen: No. But less options the better, would prefer it to be
          required.
          Stewart Bryant: Get a lot of things if keep control word. Legacy HW is
          the only argument against. But think should always be there.
          Andy Malis: As PALS co-chair, we're making CW mandatory in PALS WG,
          should be mandatory here also.
          Greg Mirsky: Need CW since transit nodes doing caching, without CW might
          be incorrectly parsed. Must have CW. First label critical.
          
          Lou Berger: Keep in mind whether data plane functions are captured in
          Arch doc. For example, is resource hierarchy/aggregation covered?
          Jeff Tantsura: EVPN active-active could be used to provide resiliency
          Greg Mirsky: Confused by IPv6 using underlying v6 structure.
          Lou Berger: Both V6 over detent and detnet over v6 are supported. Flat
          TSN domain is single Ethernet domain.
          Greg Mirsky: in detnet v6 over TSN there is nothing to be done
          Lou Berger: there still is service mapping
          Norm Finn: Is laid out in Arch and data plane drafts. Use cases: one use
          case is interconnecting TSN domains w/L2 connectivity. To make large,
          need routers. Is in the documents.
          Alexander Patrescu: IPv6 - need to connect TSN link to 802.11 link. Can
          flows be guaranteed for WiFi?
          Lou Berger: Would be interesting to see how to do this in a future
          draft. Please contribute!
          Norm Finn: As Pascal pointed out, wireless (particularly WiFi) is less
          deterministic. We don't know how to do that - if you do, let us know.
          
          Jouni Korhonen: Time for WG adoption! A good basis, not complete,
          sufficient to go forward. The DT feels the document is a solid foundation
          to move forward.
          Lou Berger: As there are no other alternative proposals and that this
          is a product of a DT, we would like to start a WG adoption poll on the
          list. As part of this call, we would also like to collect issues that will
          be addressed in post-adoption versions (i.e., post -00) of a WG document.
          Are there objections to this approach.
          Stewart Bryant: We should follow classic call for adoption and expect
          alternatives to appear soon.
          Greg Mirsky: Often see humms then adoption on list.  Agree w/ Stewart -
          just on the merit of this draft, and if there will be other documents
          there will be other documents.
          Deborah Brungard: Could state in various sections that it is a proposal
          not a final decision, and to make clear that the content is under
          discussion. This would allow others to provide input to merge in later.
          Lou Berger: We put multiple proposals in a single draft. Rev draft -00 to
          identify issues in a -01 draft sounds like a good way to capture issues
          identified during adoption.
          Stewart Bryant: Not just sequence numbers that are a concern. Adoption
          usually implies buy-in of technologies, there are areas that I have
          reservations on and have not been debated in the WG.
          Lou Berger: Such concerns can be included in the draft, section by
          section, then addressed as part of WG process.  Anyone who looks at the
          draft will immediately see which sections have open issues.
          Eric Gray: I agree with Stewart, if issues aren't in draft 00 people
          who only look at drafts will get the impression that this is the
          direction. Suggest respin individual draft first.
          Stewart Bryant: can ask for issues to be identified with draft, then
          respin individual draft including the issues, then ask for adoption
          Greg Mirsky: I like this proposal. Call for comments on current
          version. Identify ones that need to be integrated before adoption,
          then call for adoption.
          Lou Berger: We will do this and call it a two stage WG document.
          Eric: WG chair said after certain issues have been addressed will call
          for adoption.
          Lou Berger: While not the norm, we will do a two-stage adoption call on
          the document, the first stage will be to collect issues *and* to add them
          to a rev of the *individual* draft.  Then conduct a normal adoption call.
          
          > 3   10:25  20  Title:  DetNet Flow Information Model Based on TSN
          >                Presenter:  Balázs Varga
          >                Draft:
          https://tools.ietf.org/html/draft-farkas-detnet-flow-information-model-01
          
          Lou Berger: How many have read this doc?
          Before discussion of adoption, hear next talk by Mach.
          
          > 4   10:45  10  Title:  Considerations for Flow Information Model WG
          document
          >                Presenter:  Mach Chen
          >                Draft:
          
          Greg Mirsky: If use node scope performance metrics, how do we do
          this. What metrics do we need? Maximum values? Other? How are they
          obtained?
          Mach Chen: Use Maximum, since DetNet guarantees worst case.
          Greg Mirsky: How is latency measured from node? Maybe different
          discussion.
          Dean Bogdanovic: Likes grouping shown for information model. Good to
          keep same for lifecycle of draft. Are these all we need, is the more?
          Lou Berger: Matches what IETF has been doing for many years, these same
          3 blocks. Perhaps with slightly different names.
          Karl Weber: What do you mean by centralized in this context? the
          Internet? Overlapping?
          Mach Chen: Borrowed from TSN, centralized model. Mostly about how to
          use.
          János Farkas: We are talking about single admin domain, not big-I Internet
          here.
          Lou Berger: Not covering control in this WG yet. This is a reference
          model, not a requirement or plan. Control plane is currently out of
          scope.
          Karl Weber: So this is documented in the drafts?
          Lou Berger: Yes, in the architecture document
          Jeff Tantsura: So would you map in to the TE (yang) work in TEAS. Another
          option is L2SM.
          Mach Chen: Yes.
          Lou Berger: (to Mach) Are you asking for the issues you raise to be
          handled in the individual draft or in a future WG draft?
          Mach Chen: We're open to either.
          
          Lou Berger: Moving on to draft-farkas-detnet-flow-information-model-01:
          How many would like to see the -01 draft adopted now? .
          How many would like to see it improved, e.g., by incorporate Mach's
          topics first?
          No clear indication from the floor.
          János Farkas: How do we proceed?
          Lou Berger: Discuss on list. Don't wait for chairs on this. If you have
          text on these ideas, bring it. Given the lack of response from the room
          need to talk to co-chair on next steps.  Perhaps adoption call, perhaps
          not.
          
          > 5   10:55  20  Title:  DetNet Security Considerations
          >                Presenter:  Tal Mizrahi
          >                Draft:
          https://tools.ietf.org/html/draft-sdt-detnet-security-01
          
          Lou Berger: Poll: Should we have this type of document?
          How many have read it?
          How many would like to see this as a foundation?
          we will take [adoption] to the list.
          Pascal Thubert: Be realistic about impact - DetNet is intended to support
          physical systems in the real world. So if flow doesn't go through,
          machines can break, people can die.
            Lou Berger: As part of the adoption call, if you identify any issues
            you want addressed or text you want added, please send comments to
            the list.
          
          > 6   11:15  15  Title:  Implementation Report: DetNet Data Plane
          Protection
          >                Presenter:  János Farkas
          >                Draft:
          https://tools.ietf.org/html/draft-dt-detnet-dp-sol-01
          
          Pascal Thubert: Did similar demo in 6Tisch. Can miss a single packet,
          but not a certain number in a row, so for many control applications this
          is a good technique.
          János Farkas: Single link is broken for this demo.
          Jeff Tantsura: How many packets can you lose before you switch over?
          János Farkas: Any lost packet is switched, so no packets are lost.
          Lou Berger: Classic 1+1 hitless protection.
          János Farkas: Must keep track of sequence numbers (state)
          Kiran ??: Out of order seq numbers? Assume incorrectly lost a packet?
          János Farkas: Can handle this, but must keep track of delay on paths,
          etc, as spec'd in the draft.
          ?: Out of order packets? If need to be ordered, must buffer.
          János Farkas: Can handle this, somewhere you need to buffer.
          Norm Finn: IEEE 802.1CB ready to be published. Covers these kinds of
          questions. Some are more expensive answers than others. Can share URL.
          
          > 7   11:30  30  Title:  802.1 TSN Summary and Discussion
          >                Presenter:  János Farkas, Pat Thaler, Norm Finn
          >                Reference:  http://www.ieee802.org/1/pages/tsn.html
          
          Lou Berger: Doing shaping after replication? Are there 2 shapers?
          Norm Finn: Not necessarily in that order, don't read too much into it.
          Pascal Thubert: Used for constant bit rate? But transport/network
          may put into different packetizing, e.g. 1 512 vs 2 256. Broken into
          deterministic-friendly blocks?
          Lou Berger: Maybe beneficial for DetNet to provide transport protocol.
          Pascal Thubert: Thinking of problem not solution. CBR traffic may be
          broken into uneven size packets?
          Lou Berger: Do we need to talk to someone in the transport area? Must
          be solved for users, IETF is the right place.
          TSN can inform out process here.
          János Farkas: These slides are TSN only, as input to what we do in
          DetNet.
          Pat Thaler: Mac logic/state is duplicated, but not a separate address.
          John Dowdell: Any open source for TSN?
          János Farkas: The demo code is our own, not open source.
          
          Lou Berger: Will start phase 1 of data plane solution adoption process,
          so please send comments to the list.
          Lou Berger: Also likely to start adoption of Info model (as forcing
          function).
          
          > Adjourn 12:00
          
          Note takers:
          Jouni Korhonen (remote)
          Ethan Grossman
          
          



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