Hi Acee, I've responded to the thread with Shraddha. There are still 3 issues open - (1) an error with TLV reference, (2) a codepoint allocation being done without specification, and (3) regarding the updates to FlexAlgo rules.
You have asked me about (2). There is no issue with Generic Metric codepoint allocation as a sub-TLV for OSPFv2 Extended Link TLV (which also includes as a sub-TLV of ASLA TLV) - its use for FlexAlgo is fully specified in this document. My objection is to allocation for OSPFv2 TE Opaque LSA without any specification being done on how it is used. I am just asking to leave that out to a document that actually specifies the usage and let this draft progress towards publication. Hope that clarifies. Thanks, Ketan On Fri, Apr 26, 2024 at 9:23 PM Acee Lindem <acee.lin...@gmail.com> wrote: > Hi Ketan, Shraddha and Les, > > > I’m trying to conclude this thread and send this document to the AD. I’ve > read the Emails but I must admit I don’t understand all the arguments. > > > Ketan - if we have the generic-metric in IS-IS, why wouldn’t define it in > OSPF as well? If you cannot provide a compelling argument, I ‘m going to > request publication of the document send it to the actual LSR AD. > > Shraddha - I see that you included similar text in section 4.3.1 to > address Les’s comment. I guess the example referring to Flex algo 128/129 > is not needed. > > Les - I’m sure what the I-bit but I don’t see that adding it at this > juncture is a good idea unless the described protocol enhancements don’t > work without it. > > Thanks, > Acee > > > > On Apr 15, 2024, at 02:46, Shraddha Hegde <shraddha= > 40juniper....@dmarc.ietf.org> wrote: > > Hi Ketan, > > > > Thanks for reply. > > Pls see inline.. > > > > Juniper Business Use Only > > *From:* Ketan Talaulikar <ketant.i...@gmail.com> > *Sent:* Monday, April 8, 2024 2:25 PM > *To:* Shraddha Hegde <shrad...@juniper.net> > *Cc:* Acee Lindem <acee.lin...@gmail.com>; lsr <lsr@ietf.org>; > draft-ietf-lsr-flex-algo-bw-...@ietf.org > *Subject:* Re: [Lsr] Working Group Last Call for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-ietf-lsr-flex-algo-bw-con-07 > > > > *[External Email. Be cautious of content]* > > > > Hi Shraddha, > > > > Thanks for your responses. Please check inline below for clarifications > with KT. > > > > > > On Thu, Apr 4, 2024 at 9:49 AM Shraddha Hegde <shrad...@juniper.net> > wrote: > > Hi Ketan, > > > > Thanks for the review and comments. > > Pls see inline for replies. > > > > > > Juniper Business Use Only > > *From:* Ketan Talaulikar <ketant.i...@gmail.com> > *Sent:* Thursday, March 21, 2024 10:07 PM > *To:* Acee Lindem <acee.lin...@gmail.com> > *Cc:* lsr <lsr@ietf.org>; draft-ietf-lsr-flex-algo-bw-...@ietf.org > *Subject:* Re: [Lsr] Working Group Last Call for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-ietf-lsr-flex-algo-bw-con-07 > > > > *[External Email. Be cautious of content]* > > > > Hi All, > > > > I have reviewed this document and believe it needs some further work > before publication. > > > > I am sharing my comments below: > > > > 1) There is the following text in sec 2.1 and 2.2 for Generic Metric. > > > > A metric value of 0xFFFFFF is considered as maximum link metric and a link > having this metric value MUST NOT be used during Flex-algorithm > calculations [RFC9350 > <https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*RFC9350__;Iw!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmuk-veyTXw$>]. > The link with maximum generic metric value is not available for the use of > Flexible Algorithms but is availble for other use cases. > > > > I believe the FlexAlgo reference here is to > https://www.rfc-editor.org/rfc/rfc9350.html#name-max-metric-consideration > <https://urldefense.com/v3/__https:/www.rfc-editor.org/rfc/rfc9350.html*name-max-metric-consideration__;Iw!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmumv0_0Zeg$> > > > > > But the above text does not align with the RFC9350. If a link is to be > made unavailable for FlexAlgos operating with a specific Generic Metric, > then the way to do that is to omit that specific Generic Metric TLV from > the ASLA for flex-algo application. The same would apply for other > applications - just omit the metric. Why do we need a special > MAX-LINK-METRIC value for generic metric given that it is a new thing we > are introducing? > > > > <SH> I see what you are saying. Text is updated as below for ISIS and > similar for OSPF. > > “A metric value of > > 0xFFFFFF is considered as maximum link metric and a link having > > this metric value MUST be used during Flex-algorithm calculations > > as a last resort link as described in sec 15.3 of RFC[9350] > > > > KT> Thanks - that works. Perhaps also clarify that to make the link > unusable by FlexAlgo using that generic metric, the advertisement of the > particular generic metric can be skipped. > > <SH2> ok > > > > > > 2) This comment is specific to OSPF given the encoding differences it has > with ISIS. Section 2.2 allows for Generic Metric TLV to be used in too many > places without clear specification of what it is used for - this is a > potential pitfall for interop issues. RFC9492 provides helpful directions > for us here. > > a) This draft specifies FlexAlgo extensions, it is natural that Generic > Metric be advertised under ASLA TLV. No issues here. > > b) This draft does not specify anything about use of generic metric in > base OSPF and as a reminder there is nothing like L-bit in OSPF encoding. > Therefore, it does not make sense to advertise Generic Metric outside of > ASLA and under the OSPFv2 Extended Link TLV or OSPFv3 Router Link TLV. > > c) This draft does not specify anything about use of generic metric with > RSVP-TE/GMPLS. Therefore, it does not make sense to advertise Generic > Metric in the TE Opaque LSAs. > > We can have specific documents that introduce (b) or (c) when there is a > proper specification. > > <SH> Generic metric is a link attribute and can be used by other > applications apart from Flex-algo. > > I don’t see a reason to not take code-points under other applicable LSAs. > > > > KT> I disagree on this one. There is a reason why what is proposed in the > draft for ISIS is OK - due to the L-bit in ASLA, we need codepoints both > under ASLA and at the top level for FlexAlgo. There is no L-bit in OSPF and > therefore this does not apply. The code-points can be allocated when the > behavior is specified for those other LSAs and applications (beyond > FlexAlgo) in OSPF. We should not set the precedent for allocating > code-points for TLVs without any defined use or behavior. > > > > <SH2> Early code points are taken and implementations underway for other > applications. > > > > “Implementations MUST support sending and receiving generic metric > > sub-TLV in ASLA encodings as well as in the TLV 22/extended link > LSA/TE-LSAs. > > The usage of a generic metric by an individual application is subject to > the same > > rules that apply to other link attributes defined in respective standards.” > > > > The above text clarifies the use of generic metric by individual > application. > > > > 3) Please introduce a reserved field to pad the OSPF FAEMD sub-TLV to a 4 > octet boundary as is the convention in OSPF - > https://www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html#section-3.2.2 > <https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*section-3.2.2__;Iw!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmunYcymQgw$> > > <SH> OK > > > > KT> Thanks. > > > > > > 4) In section 3.2.2 there is the following text for OSPF. Could you please > use the TLV/sub-TLV name? OSPF folks are not good at remembering numbers ;-) > > > > The Min Unidirectional Link Delay as advertised by *sub-sub-TLV 12* of > ASLA sub-TLV [RFC8920 > <https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*RFC8920__;Iw!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmun5uDKc7A$>], > MUST be compared against the Maximum delay advertised in the FAEMD sub-TLV. > > <SH> changed to “The Unidirectional Link Delay as advertised by *sub-sub-TLV > 12”* > > > > KT> Perhaps my comment was not clear. The following text would be more > accurate: > > > > The Min Delay value advertised via the Min/Max Unidirectional Link Delay > sub-TLV [RFC7471] of the ASLA sub-TLV [RFC8920 > <https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*RFC8920__;Iw!!NEt6yMaO-gk!HoQCxz15c5OoUVXjpmPpCU0N94Ex0cMuET6hFT8l6FE_kNkB58lpI-LSmXBUJvY4IdViL2mzTjVwvp4nyibk3A$>], > MUST be compared against the Maximum delay advertised in the FAEMD sub-TLV. > > <SH2> I think there is a misunderstanding here. You are proposing to use > sub-tlv 13 where as the text in the draft clearly proposes to use sub-tlv > 12. This probably justifies why it is important to specify sub-tlv number > > And not just name. > > > > > > 5) Do we want to call out that the reference bandwidth approach requires a > router to compute and maintain a per link per algo bandwidth metric for > every link in that algo topology. It may not be very obvious to some. > > <SH> updated as below > > “Advertising > > the reference bandwidth in the FAD constraints allows the metric > > computation to be done on every node for each link. > > The metric is computed using reference bandwidth and the advertised > link bandwidth. > > Centralized control of this > > reference bandwidth simplifies management in the case that the > > reference bandwidth changes” > > > > KT> The above text is not really needed IMHO. My point was more about the > implementation detail - for the flexalgo computation, we need to maintain > this info on a per link per algo topology basis in the link-state data > store used for path computation. I will leave it to the authors if this is > needed or is obviously clear to implementers. > > <SH2> I don’t see the need to add implementation specific details. > > > > > > 6) There are a lot of procedures which are common to both OSPF and ISIS > and are repeated in each section instead of a common section. It would be > easier (and avoid errors) if there was some consolidation. > https://www.rfc-editor.org/rfc/rfc9350.html#section-5 > <https://urldefense.com/v3/__https:/www.rfc-editor.org/rfc/rfc9350.html*section-5__;Iw!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmumpoQRYAA$> > provides a good reference for such an organization of text. > > <SH> There is repetition in some cases but its not much so it seems to me > leaving it as is for clarity may be better. > > > > KT> This is an editorial comment so I leave it to the authors. My concern > is that great care/diligence is required through the rest of the > publication process to ensure that when anything is changed or updated for > one IGP, it is done appropriately for the other as well - it may be > copy/paste case when the change is IGP agnostic but may need careful > consideration when related to the specific IGP mechanics. > > > > > > 7) Regarding > https://www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html#section-6 > <https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*section-6__;Iw!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmumnzxX7UA$>, > it seems like we want to retain a numbering ordering of rules/sequence for > flex-algo as extension documents are introduced. Am I correct? If so, then > this document should formally "update" RFC9350 since it is changing the > "set of rules/sequence" for FlexAlgo computations. Further such extensions > will also need to keep updating the base spec similarly. I would suggest > that a full set of rules that is a union of what is in RFC9350 and rules > added by this draft are maintained in an Appendix section. Other documents > in the future can similarly maintain the latest set of rules. > > <SH> This draft is adding 2 new rules at the end of existing rules. Its > not modifying or changing the order. > > I don’t see what value it is going to add by repeating the set of rules in > Appendix. > > > > KT> What happens when another FlexAlgo document adds more rules? What > happens when some FlexAlgo document wants to insert rules in the middle of > existing ones instead of appending at the end? My point is that if there is > a desire to establish a "live" set of rules in specific orders, then we > need to leave a trail of document "updates" on the base FlexAlgo that one > can refer to know how these "live set of rules" are getting "updated" by > this and future documents. I am thinking of this on lines similar to an > update for an FSM. > > <SH2> It’s a matter of choice. For ex RFC 8029 > > Has so many updates to the Rules but each update only lists > the changes. > > I am fine with whatever WG decides to do. > > I want to hear if anyone in WG has an opinion on adding > Appendix. > > > > Thanks, > > Ketan > > > > > > > > 8) Please fix idnits warnings - some are related to obsolete references > while others are related to formatting. There are also some > spelling/grammar errors. > > <SH> ok > > > > Thanks, > > Ketan > > > > > > On Tue, Feb 20, 2024 at 3:56 AM Acee Lindem <acee.lin...@gmail.com> wrote: > > > This starts the Working Group Last call for > draft-ietf-lsr-flex-algo-bw-con-07. At least some of the flex algorithm > enhancements described in the document have been implemented. > > Please send your support or objection to this before March 5th, 2024. > > Thanks, > Acee > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr > <https://urldefense.com/v3/__https:/www.ietf.org/mailman/listinfo/lsr__;!!NEt6yMaO-gk!DwOojW2YZ48IROz9qMyyh7uKj3rYC-09avEhFQtcPkvxJ5mKF5Cyy6qSVvDJ89s9DmAUVwsT_pgfmukG-EHJRw$> > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr > > >
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