Les, Let me clarify - rereading your email again where you clearly suggest using 128 values for flex-algo. (I've been working all evening - except for ducking out for that 10 minutes to chase the kids to bed in the middle of that last email.)
a) I found the need for an SR Algorithm field to be limited, given our experience with different IGP algorithms. I would also be stunned if we got to 10 different algorithms. b) Having unclear semantics because an algorithm only makes sense for BIER or only makes sense for an IGP-specific technology is not good. c) Adding the complexity to consider how and when to use an algorithm or similar new feature that makes sense for a link-state IGP - to then also consider if it can apply to BIER and if it can work in non-link-state IGPs - would only make sense if it were balanced by an equal technical benefit. These drafts were WGLCed in June - with no BAR. In October, I did not just insist on a IANA registry for the BAR in the BIER registries - because it was claimed that would let the documents progress and not force to an assumption. I regret that decision - given the poor efforts to force a registry merge. IF you and Ice truly believe that this is the technically correct thing to do, then you would make substantive technical arguments instead of this sophistry. I have given several more chances to allow this WG to discuss whether any changes are needed or are desirable. I am pushing for technical discussion. I am quite disappointed in the level of discourse; the BIER-WG has traditionally worked very collegially with substantive technical points. Regards, Alia On Mon, Feb 19, 2018 at 10:11 PM, Alia Atlas <akat...@gmail.com> wrote: > Les, > > On Mon, Feb 19, 2018 at 9:32 PM, Les Ginsberg (ginsberg) < > ginsb...@cisco.com> wrote: > >> I am very sympathetic to doing “as little as possible” given we are >> talking about documents which are going through final reviews. >> >> At the same time, I think defining the authoritative source for algorithm >> values is important. >> >> >> >> I therefore agree w Ice – let’s keep the current 8 bit algorithm value – >> but make it clear that the identifiers come from the IGP Registry. >> > > I do not hear from you or Ice a clear technical reason nor willingness to > address the concerns that I raised about the impact > on the use of BIER. > > I see no technical reasons being used to recommend combining the BIER BAR > registry and the IGP Algorithms registry. > > Andrew – I do not think there is agreement on what the function of a “BAR >> sub-type” is. Therefore I am not comfortable in adding it to the drafts. >> >> Certainly this may prove to be useful, but let’s add it when we know how >> it will be used and how to assign values to it. That requires more >> discussion than can reasonably be had in the current context. >> >> >> >> Tony / Alia – the argument that 256 algorithm values is not enough for >> all use cases (BIER specific and IGP specific and Babel specific…) – or >> even that 128 is not enough (if we allow the Flex-Algo proposal to reserve >> half of the space) – simply does not ring true to me. >> >> If I waited for you to buy me a beer when we reached 10 algorithms I >> likely will go thirsty for a very long time. >> > > It is fascinating to see that you believe me too busy to keep up on the > side discussions happening - or perhaps merely too distracted to > recall the emails discussing acquiring half of the IGP Algorithm space for > flex-algo. I do talk to my WG Chairs. > > Please engage substantively with technical arguments. If you have them, > you are more than capable of representing them > accurately. > > So Option E seems best to me. >> > > That was not part of my listed options. > > Regards, > Alia > > >> >> Les >> >> >> >> *From:* BIER [mailto:bier-boun...@ietf.org] *On Behalf Of *Tony >> Przygienda >> *Sent:* Monday, February 19, 2018 6:20 PM >> *To:* Dolganow, Andrew (Nokia - SG/Singapore) <andrew.dolga...@nokia.com> >> *Cc:* BIER WG <b...@ietf.org>; IJsbrand Wijnands <i...@cisco.com>; >> isis-wg@ietf.org list <isis-wg@ietf.org> >> *Subject:* Re: [Bier] [Isis-wg] BAR field length in >> draft-ietf-bier-isis-extensions and draft-ietf-bier-ospf-extensions >> >> >> >> My reaction to AD's options: >> >> IF you prefer or can accept the current status, but think there should be >> an IANA registry >> as is usual for managing code-points, please say so. No more >> justification is needed. >> >> >> >> >> +1 to this option, i.e. current status with IANA BIER BAR registry. >> >> I think we have a clear and current case which is anchored already in the >> architecture RFC as section 6.9 >> >> The draft https://tools.ietf.org/html/draft-zzhang-bier-algorithm-00 >> goes into more detail in this respect and I hope the draft being adopted >> and at least a single BAR value being assigned to deal with brownfield >> deployments today where not all routers support BIER. This clearly >> necessitates a BIER BAR registry. >> >> >> IF you prefer Option B, C, and/or D, please say so with your >> explanation. More technical depth than "'we might need it" would be >> helpful; the availability of sub-TLVs already >> provides future proofing. >> >> >> +2 for Option B). Albeit we can meet future use cases with BAR subtype >> being a sub-TLV a bar type/bar subtype 16 bits field (subtype with or >> without registry and of course we can name those things differently) all >> sub-TLVs in IGPs are traditionally “optional”, i.e. adding sub-TLVs later >> _may_ cause backwards compatibility problems. Defining the subtype today >> will allow us to specify that only type/subtype 0/0 is well defined & any >> unknown type/subtype combination must be avoided. The subtype will allow >> for BAR 0 or future BAR types to understand that subtype is in a sense a >> “mandatory sub-TLV” and the routers sending out such subtype must be >> avoided, even if the type itself is known. Several possibilities come to >> mind immediately such as using Unicast IGP Algorithm Registry as subtype >> for certain BAR values or accommodate interesting, future work like Flex >> Algo into BIER right after IGP RFCs are available which IMO would present a >> very beneficial future direction for BIER technology cleanly governed by a >> BIER BAR registry. >> >> PS: I think we should control the urges of workgroup participants to >> explore the number of letters in the roman alphabet that we can use to >> introduce their preferred solutions if we want to get to some kind of >> consensus on this thread. >> >> PPS: Option E has been discussed in the last 16-bit thread to the point >> of logical conclusion of a "all routing protocols under the sun algorithm >> registry" and found to be a rathole I thought ... >> >> >> >> >> >> >> On Mon, Feb 19, 2018 at 6:09 PM, Dolganow, Andrew (Nokia - SG/Singapore) < >> andrew.dolga...@nokia.com> wrote: >> >> All, >> >> >> >> As we discussed here (as a WG) and in this topic: >> >> - We need to have ability to define way for independent BIER >> computation algorithms (for BIER specific computations or other use cases, >> some of which Alia highlighted in her email below) >> - We want to have extensibility to use other non-BIER specific >> algorithms (as others brought up) >> >> >> >> The original draft can be argued not to provide both of those >> capabilities, and thus Option A below (marked as Current status) really >> just defers the issue. I find Option E that Ice added also >> counterproductive as it eliminates the top use case above. Thus we really >> left with options B, C, D as a compromise. From those, Option B seems to me >> the best: >> >> - It meets the requirements above >> - It allows a clean implementation (as opposed to Option C which is a >> bit more kludgy). Thanks to a sub-TLV defining what BAR field carries – a >> BIER-specific algorithm defined in BIER specific registry (a registry that >> should be BIER specific, regardless of IGP used), or something else to >> meet >> needs expressed by others, we meet the requirements from those who wanted >> to change the Current status >> >> >> >> Option C/D are acceptable alternatives; however, Option B seems >> technically cleanest, most flexible, and meeting all requirements. >> >> >> >> Andrew >> >> >> >> >> >> *From: *Isis-wg <isis-wg-boun...@ietf.org> on behalf of Alia Atlas < >> akat...@gmail.com> >> *Date: *Tuesday, February 20, 2018 at 12:05 PM >> *To: *"(Ice) IJsbrand Wijnands" <i...@cisco.com> >> *Cc: *BIER WG <b...@ietf.org>, "isis-wg@ietf.org list" <isis-wg@ietf.org> >> *Subject: *Re: [Isis-wg] [Bier] BAR field length in >> draft-ietf-bier-isis-extensions and draft-ietf-bier-ospf-extensions >> >> >> >> Ice, >> >> >> >> On Mon, Feb 19, 2018 at 7:57 PM, IJsbrand Wijnands <i...@cisco.com> wrote: >> >> Alia, >> >> >> >> I appreciate that you have finally decided to discuss this on the BIER >> mailing list. >> >> >> I know that there are individual drafts draft-ppsenak-ospf-sr-flex-algo-00 >> and draft-hegdeppsenak-isis-sr-flex-algo-02. >> I see a bit of discussion on the is-is mailing list and at IETF 100, but, >> of course, no WG adoption. >> >> I see BIER as a fundamental technology that can be used in different >> situations. For instance, there is not merely >> discussion of how Babel and BIER could interact - but actual code (thanks >> Sandy!); of course, that is not a WG-adopted >> draft yet either, so this is merely a thought experiment example. How do >> the different algorithms >> work for an IGP that isn't link-state? What about the ideas around >> using BIER with caches? Are there issues there? >> What about algorithms that make sense for BIER or multicast - but not for >> unicast? >> >> IANA registries are not price prohibitive. Why would we tie BIER to the >> link-state IGP registry? >> >> >> >> We are talking about what needs to be advertised in OSPF and ISIS in >> order to select the BIER underlay. We are not discussing Babel or any other >> candidate underlay technologies for BIER. Moreover, we are not limiting any >> new innovation with BIER regarding the underlay. This discussion is >> strictly related to the drafts in the title. >> >> >> >> I do not hear you making a technical argument. >> >> >> >> This is an architectural argument! >> >> >> >> An architectural argument can't also limit itself to the drafts in the >> title. >> >> >> >> If it sounded like the IANA registry was suggested as separate for BIER >> OSPF and BIER ISIS, then your attempt to reframe the conversation might be >> reasonable. Let me clarify - I see no current reason for an OSPF BAR >> registry and an ISIS BAR registry; it would just be a BAR registry. Perhaps >> >> that clarification is a good reason to get the IANA registry included in >> the next update? >> >> >> >> The routing layer is separate from the BIER layer. The BAR is for the >> BIER layer. >> >> >> >> Regards, >> >> Alia >> >> >> >> >> >> Hope this clarifies, >> >> >> >> Thx, >> >> >> >> Ice. >> >> >> >> >> Regards, >> Alia >> >> >> On Mon, Feb 19, 2018 at 7:03 PM, IJsbrand Wijnands <i...@cisco.com> wrote: >> Hi Alia, >> >> There is one more option that I think is not fully covered from the >> choice of options related to getting a registry. >> >> The topic of the discussion is what information we need to pass in the >> IGP in order for BIER to select the correct underlay. What identifies the >> underlay is really what ever information is needed to select the Table >> (MT-ID) and Algorithm. An example of Algorithm work that is going on is >> Flex-Algo. My preferred option is to align with what ever the IGPs are >> using to identify the Algorithm. >> >> Option E: Change BAR into “IGP Algorithm” registry as documented in >> https://www.iana.org/assignments/igp-parameters/igp- >> parameters.xhtml#igp-algorithm-types >> >> Thx, >> >> Ice. >> >> On 19 Feb 2018, at 13:51, Alia Atlas <akat...@gmail.com> wrote: >> >> As the Sponsoring AD for draft-ietf-bier-isis-extensions-07 and >> draft-ietf-bier-ospf-extensions-12, I have been following the discussion >> on the mailing list with interest. >> >> I have not seen clear consensus for any change. >> >> Let me be clear on what I see the options are from the discussion. Then >> I'll elaborate >> a bit on how you can express your perspective most usefully. >> >> 1) Current Status: Bier Algorithm (BAR) field is 8 bits. Currently, >> only value 0 is specified. The drafts do not have an IANA registry - with >> the expectation that one will be created when the first additional use is >> clear. It is possible that there will be objections from the IESG to >> progressing without an IANA registry. Given the lack of clarity for future >> use-cases and after discussion, I decided not to force one after my AD >> review - but I will not push back against having a BIER IANA registry if >> raised by others. >> >> 2) Option B: Add a BAR sub-type of 8 bits. This would modify the >> current TLVs. >> Define an IANA registry for the BAR type. The meaning of the BAR >> sub-type derives >> from the BAR type. We can debate over the registration policy for >> the BAR type. >> >> 3) Option C: Change the BAR field to be 16 bits and define an IANA >> registry. Part of the range can be FCFS with Expert Review, part can be >> Specification Required, and part can be IETF Consensus. >> >> 4) Option D: At some point in the future, if there is an actual >> understood and documented need, a BAR sub-type could be added a sub-TLV. >> The length of the BAR sub-type could be determined when the sub-TLV is >> defined. >> >> Given >> >> a) option D exists >> b) there is currently only one defined value for BAR >> c) I do not see strong consensus for change to one particular other >> option >> >> I see no current reason for a change and I certainly see absolutely no >> reason for >> a delay in progressing the documents. >> >> I do want to be clear about what the WG wants to do on this issue. >> Therefore, here is >> my following request. >> >> Please send your feedback to the mailing list as follows: >> >> IF you prefer or can accept the current status, please say so. No more >> justification >> or reasoning is required. I just don't want the bulk of folks who are >> content to be >> overlooked by those suggesting change. >> >> IF you prefer or can accept the current status, but think there should be >> an IANA registry >> as is usual for managing code-points, please say so. No more >> justification is needed. >> >> IF you prefer Option B, C, and/or D, please say so with your >> explanation. More technical depth than "'we might need it" would >> be helpful; the availability of sub-TLVs already >> provides future proofing. >> >> IF you have a clear technical objection to why the Current Status is not >> acceptable, >> please express that - with clear details. >> >> IF you feel that additional code-points should be allocated in a BAR IANA >> Registry or >> have thoughts on the appropriate policy, please say so with your >> explanation for what >> those should be. >> >> Unless I see clear and strong consensus for something other than the >> Current Status, >> that will remain. >> >> IF there is clear and strong consensus for Option B, C, or D, or adding >> an IANA registry with particular values, then it will be possible to have a >> change up through this Weds night - with a 1 week WGLC on that particular >> technical change. >> >> My priority is to have the base BIER specifications published as Proposed >> Standards so that more BIER implementations and deployment can be done. I >> would like the WG to wrap up the core work (as expressed in the proposed >> recharter) so that you all can look >> at how to use it. >> >> Given this topic was raised last Weds and given that there are no >> technical objections raised to the documents as are, there isn't much time >> - so please just respond to this email ASAP. My deadline for a decision is >> 6pm EST on Weds. >> >> Regards, >> Alia >> >> _______________________________________________ >> BIER mailing list >> b...@ietf.org >> https://www.ietf.org/mailman/listinfo/bier >> >> >> >> <PastedGraphic-6.png> >> >> >> >> [image: cid:6D5DA0C0-E3D6-4998-A2B2-FBE7253DB66D@cisco.com] >> >> >> >> >> >> >> _______________________________________________ >> BIER mailing list >> b...@ietf.org >> https://www.ietf.org/mailman/listinfo/bier >> >> >> >> _______________________________________________ >> Isis-wg mailing list >> Isis-wg@ietf.org >> https://www.ietf.org/mailman/listinfo/isis-wg >> >> >
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