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Rtg Area: Alvaro Retana, Martin Vigoureux, John Scudder | 2018-Feb-23 —  

IETF-110 lsr minutes

Session 2021-03-08 1700-1900: Room 6 - lsr chatroom


minutes-110-lsr-00 minutes

          IETF 110 LSR Meeting Minutes
          Chairs: Acee Lindem
                  Chris Hopps
          Secretary: Yingzhen Qu
          Date: Monday, 8th March 2020
          Time: 17:00 – 19:00 UTC+1
          0   17:00   15m WG update   Acee/Chris
          Xuesong:   For "authors believe it's ready for WG LC", does it mean
                     there is no WG consensus yet?
          Acee:      The consensus will be determined during WG LC.
          Chris H:   The authors believe a draft is ready, if someone doesn't
                     think so, they can comment.
          Tony Li:   draft-ietf-lsr-dynamic-flooding implemented, but there
                     is no interoperability yet.
          Chris B:   Dynamic flooding on Dense topo, is it Alvaro's comments on
                     adding OSPF?
          Acee:      No, it's SRv6 extension.
          Chris:     For flooding parameters, Bruno has asked WG adoption, but
                     there are two drafts and there are still tests going on. The
                     work is progressing. There is no rush on adoption. Speaking
                     as WG member, we may need to think out of the box.
          Xuesong:   I have seen OSPF/ISIS SRv6 YANG adoption call in the queue
                     for long time, just wondering when it will happen?
          Acee:      There is nothing controversial about these two drafts,
                     should happen soon.
          Alvaro:    Welcome John Scudder as new LSR AD. He's taking over LSR
                     from me. Thank you for the WG, after merging OSPF and ISIS,
                     it's been working great. All the things done in last
                     3-4 years, it's lot of work. It's great to see the two
                     protocols progress together.
          Chris H:   Thank you for all your hard work Alvaro.
          1   17:15   10m OSPF Transport Instance
          Yingzhen Qu
          Linda       What's the application ID here? It it a network application or
          Dunbar:     end-user application?
          Yingzhen:   It can be any application that wants to use OSPF transport
                      instance to disseminate application-specific information.
          Linda:      If I'm an application attached to a router, can I create my
                      own sub-tlv to be attached?
          Yingzhen:   Yes.
          Linda:      How do I tell router I need this information?
          Yingzhen:   That's out of scope for this document.
          Acee:       It's meant for non-routing information. So I guess you don't
                      mean a prefix, you mean an end-point for an application.
          Uma         The MEC computing use case in the draft is not correct,
          Chunduri:   There is no way for a UE to communicate with the network
          Yingzhen:   OSPF transport instance can only disseminate non-routing
                      information inside ospf network, how UPF communicate with
                      ospf network is out of scope of this draft. UPF can run an
                      OSPF transport instance, or use other ways to communicate.
          Chris H:    Worst case just pull the use case out of the draft.
          Tony Li:    "Routing protocols are not dump trucks", this will impede
                      the operation of the protocol.
          Yingzhen:   That's why we're using a transport instance. It's for
                      non-routing information, not route calculation.
          Tony Li:    We should design a different protocol for doing this.
          Chris:      Did you not like genapp for ISIS either?
          Tony Li:    Yes, it's not OSPF specific.
          Acee:       Let's move this to the list.
          Aijun Wang: What's sparse topology?
          Yingzhen:   An OSPF transport instance can run on a different topology
                      from the routing instance. Let's discuss more on the list.
          2   17:25   10m IGP Flex Algorithm
          Peter Psenak
          Alvaro:    I'm glad you guys caught that as this was next in my queue.
                     Since we're going to go for another last call, and this
                     seems to be significant change, I'm going to bump the
                     document back to the WG. Please put it on John's queue.
          3   17:35   15m Flexible Algorithms Bandwidth Constraints
          William Britto
          Acee:      Speaking as WG member. This is a good example how flex-algo
                     can be used. Whatever we talk about the measurement of the
                     delay, jitter, etc, there are questions as to how it is done.
                     I know it's out of scope, but it will be helpful to provide
                     guidance on frequency of updating such info.
          William:   Thanks.
          Misha:     Just wondering, how to avoid instability?
          William:   We expect operators use with caution. If you want to bring
                     down a link, you have to define the threshold and make sure
                     it's safe. For dynamic bandwidth, it only changes when
                     members change.
          Uma:       Useful draft. I'd like to see the impacts to packet reordering.
          Jie:       The bandwidth metric, is it tightly coupled with flex-algo?
          William:   It's generic, can be used in any application.
          Jie:       please clarify it. In this draft, latency is on a particular
                     link instead of end-to-end, what's the use case?
          William:   You may want to exclude a particular link.
          Shraddha:  Just clarifications. it's basically to dynamically exclude
                     some links when the bandwidth or latency change. The
                     measurement and how often to update the parameters is out
                     of scope. We will add text about area partitions.
          4   17:50   10m Using Flex-Algo for Segment Routing based VTN
          Yongqing Zhu/
          Jie Dong
          Tarek Saad: Flex-algo has overhead of advertising the definition, nodes
                      consuming it, and doing SPF with the respective algorithm.
                      You'll soon realize you can't do as many flex-algos as you'd
                      want. Any consideration for this limitation?
          Jie:        Regarding scalability, we do have a section on scalability
                      in the draft. We also have other drafts that support multiple
                      VTNs sharing the same topology, it requires more extensions
                      to the control-plane though.
          Tarek:      Why would we standardize something we know is unscalable?
          Jie:        we have another draft in TEAS. Each mechanism has different
                      pros and cons, scalability is one aspect.
          Chris:      We should discuss this on the list before we get into an
                      adoption discussion.
          Peter       What you're trying to do here is advertise VTN specific info
          Psenak:     about the link. The way you're trying to do this is by
                      hijacking the bundle advertisement, pretending it's
                      specific to the VTN. I'm not sure that's the right approach.
                      There's no direct info about the VTN for which you advertise
                      the information, too error-prone. If you want to advertise
                      VTN-specific stuff, define your own VTN-specific information,
                      don't use hijacking and mapping.
          Chris H:    As a WG member, when I saw admin color, I was hoping this
                      would just be an informational draft.
          Jie:        to Peter's comment, we reused admin group to correlate with
                      flex-algo ID, is based on existing flex-algo idioms.
                      Introducing a dedicated identifier would be a different
                      approach that would require more extensions.
          Chris H:    Again, this is good for discussion on the list.
          5   18:00   8m  IGP Flexible Algorithm with L2bundles
          Ran Chen
          Peter P:   As a flex-algo co-author, we never intended to use L2 links
                     in the flex-algo calculations. Do we want to do this? Seems
                     like the right solution is SR-TE. It's *possible* to do it
                     inside flex-algo, but I'd prefer to keep it L3 specific.
          Ran:       Thanks, we've discussed your mails, but we think the problem
                     needs to be solved. See section 5.
          Chris:     Would be helpful if more people would engage on the list.
          6   18:08   8m  Algorithm Related IGP-Adjacency SID Advertisement
          Ran Chen
          Tony Li:    We already have ample mechanisms within flex-algo for doing
                      this kind of thing, for example coloring. Why do we need
          Ran:        that was in my motivation slide.
          Tony Li:    I'm not following you but OK.
          Acee:       Please post the question on the list so it can be discussed
          7   18:16   10m IGP Extensions for SR Slice Aggregate SIDs
          Tarek Saad
          Acee:       As chair, I think the whole slice TE concept would needs
                      to be adopted in TEAS first, and whether or not the concept
                      of slice-aggregate is the right one, before we jump to
          Tarek:      Sure. We are working on that in TEAS.
          Peter P:    How many of these aggregates are we talking about. You just
                      mentioned flex-algo doesn't scale to hundreds, and I agree.
          Tarek:      Good question, I don't claim to have the final answer. We
                      need to be realistic, shooting for the order of hundreds to
                      a thousand. The point of our proposal is that we want to
                      decouple topology and IGP path computation (primary and
                      from the number of forwarding treatments.
          Peter P:    Hundreds or thousands of these? Could be a scalability issue.
          Tarek:      Hundreds of SAIDs.
          Tarek:      Our proposal in SPRING has two options. One is purely
                      data-plane, but that has implications for hardware, so we
                      also have this option.
          Jie:        The drafts you mentioned in TEAS and SPRING have overlap/
                      conflict with (for example) enhanced VPNs. We need to
                      resolve those first.
          Tarek:      We're presenting at the TEAS meeting and we're open to
          Jie:        For scalability, we also have a draft in TEAS. Let's also
                      discuss that.
          Uma:        For hundreds to thousands slice aggregates, why do you
                      present SAID with 32 bits?
          Tarek:      we'll think about it. we're open to reducing the field
                      size if required.
          Acee:       If field size is the only problem, there's no barrier!
          8   18:26   10m OSPF Extension for 5G Edge Computing Service
          Linda Dunbar
          Chris H:    As WG member, I don't have time for the philosophizing,
                      but you're trying to push application load-balancing into
                      routing and ask routing to do that. That is a big ask, a
                      big change. You have to add the info because anycast solves
                      the simple problem, very well. But not for you because
                      you're trying to do more. You will get pushback on the
                      whole idea from people who don't want routing to do this.
                      You can do this in other ways.
          Linda:      In 3gpp there's project called Edge Computing, and anycast
                      is proposed as a way to do load-balanceing. We're not
                      trying to replace application load-balancers.
          Chris:      I get it, but you are not actually using anycast, you're
                      expanding it. I'm not saying its good or bad I'm just
                      saying it's a big ask.
          Acee:       I'll take it to the list, but I'm happy you fixed the
          From the chat:
          Joel Halpern: This seems to be the same confusion of stuffing things
                      into the routing system that parts of the dyncast documents
                      have. Don't solve this problem in routing.
          Tantsura:   +1
          Tony Li:    +1
          Randy Bush: Where to solve it if not in routing? App layer?
          Tony Li:    In the load balancer?
          Randy:      L4 or L7?
          Jeff T:     DNS + anycast works pretty well
          Gyan:       +1
          Joel:       One approach I have discussed is a mapping system (LISP,
                      ALTO, ...) Even better from my perspective is to teach the
                      end-systems to ask an appropriate control component (not
                      the routing) for the information it needs.
                      DNS still claims not to give context-sensitive answers. If
                      we ignore that, sure, DNS works.
          Randy:      I assure you that there are context sensitive DNS
          Jeff T:     IGP should be the last place where this kind of stuff is
                      pushed to.
          Joel:       @Randy - I hope I was careful on the phrasing. I am sure
                      there are as many abuses of DNS as there are of the IGPs.
                      Using DNS for the query protocol doesn't bother me.
          9   18:36   10m Updates of PUA mechanism
          Gyan Mishra(Verizon)
          Aijun Wang(China Telecom)
          Acee:       As a WG member, two comments (made them last time but they
                      were not taken). First, how do you know which holes you're
                      protecting? Are they configured on the ABRs? How do you
                      know a priori what the ABR is missing if it's not
          Gyan:       I don't know if I'm completely understand your question,
                      but I would say if the prefix is missing within the range
                      that notification happens from the...
          Acee:       You're assuming you know about the prefix, and then it goes
                      away. You won't protect anything you don't know about when
                      you come up, because it's stateful.
          Gyan:       Yes, anything that you know about.
          Acee:       It's somewhat timing-based. It's kind of broken in that
                      way. The other problem is the way you're doing it, if not
                      everyone in the domain supports it, you'll attract traffic
                      toward the black hole - the prefix originator T:V is the
                      wrong method for this.
          Gyan:       thanks for the comments, we'll take it to the list for more
          10  18:46   10m IS-IS Multi-Flooding Instances
          Yali Wang
          Acee:       As a WG member, you say it's easier to implement. Have you
                      implemented it?
          Yali:       this is the result of our analysis. Not from implementation
          Acee:       I would disagree that it'll be easier to implement. We can
                      discuss on the list.

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