Hi Shraddha, > On Sep 1, 2024, at 23:43, Shraddha Hegde > <[email protected]> wrote: > > Acee, > > > Are we still debating whether generic metric is applicable to OSPF TE LSAs. > I thought we had closed on the topic and the code points taken a while ago.
Yes - there is “passive” debate in that Ketan’s suggested text doesn’t include the OSPF TE LSAs. I thought it was resolved as well. Thanks, Acee > > OR > > Are you suggesting to qualify the RFC 3630 and RFC 5305 with TE applications > as below? > > " > The usage of a generic metric by an individual application is subject to the > same rules that apply to other link attributes as defined in [RFC9479] > [RFC9492] [RFC9350] and to TE applications as defined in [RFC3630] [RFC5305]" > > Rgds > Shraddha > > > Juniper Business Use Only > -----Original Message----- > From: Acee Lindem <[email protected] <mailto:[email protected]>> > Sent: Saturday, August 31, 2024 12:31 AM > To: Les Ginsberg (ginsberg) <[email protected] > <mailto:[email protected]>> > Cc: Shraddha Hegde <[email protected] <mailto:[email protected]>>; > Ketan Talaulikar <[email protected] <mailto:[email protected]>>; lsr > <[email protected] <mailto:[email protected]>>; > [email protected] > <mailto:[email protected]> > 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] > > > Les - > As document shepherd, I'm trying to advance the document by facilitating > discussion of the pro and cons of generic metric applicability to OSPF TE > LSAs. > I don't feel that strongly one way or another (as long as TE LSAs are not > used for non-TE applications). Hence, my input to the WG is to dispense with > the passive proposal of competing text and discuss the remaining generic > metric question - "To TE or not to TE." > > Acee > >> On Aug 30, 2024, at 1:24 PM, Les Ginsberg (ginsberg) >> <[email protected]> wrote: >> >> Acee – >> The references to RFC 3630 (and RFC 5305) are not new (though some editorial >> changes were made). >> I for one would appreciate it more if you could provide input rather solicit >> it. >> Les >> From: Acee Lindem <[email protected]> >> Sent: Friday, August 30, 2024 9:59 AM >> To: Les Ginsberg (ginsberg) <[email protected]> >> Cc: Shraddha Hegde <[email protected]>; Ketan Talaulikar >> <[email protected]>; lsr <[email protected]>; >> [email protected] >> Subject: Re: [Lsr] Working Group Last Call for "Flexible Algorithms: >> Bandwidth, Delay, Metrics and Constraints" - >> draft-ietf-lsr-flex-algo-bw-con-07 >> What I’m trying to do is solicit direct discussion on the generic metric >> applicability in the OSPF TE LSAs rather than further alternate text >> proposals. >> Thanks, >> Acee >> >> >> On Aug 30, 2024, at 11:53, Les Ginsberg (ginsberg) >> <[email protected]> wrote: >> I think the problematic text is in Section 2 final paragraph: >> It now reads: >> “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 as defined in [RFC3630], >> [RFC5305], [RFC9479], [RFC9492] and [RFC9350].” >> What was suggested was: >> “The usage of a generic metric by an individual application is subject to >> the same rules that apply to other link attributes as defined in [RFC9479] >> [RFC9492] [RFC9350].” >> The problem with the revised text is that the paragraph is specifically >> talking about ASLA use cases, but the set of RFCs referenced includes >> documents which have nothing to do with ASLA. >> I would suggest that the draft be revised to follow Ketan’s original >> suggestion. >> Les >> From: Acee Lindem <[email protected]> >> Sent: Friday, August 30, 2024 8:34 AM >> To: Shraddha Hegde <[email protected]> >> Cc: Ketan Talaulikar <[email protected]>; lsr <[email protected]>; >> [email protected] >> Subject: [Lsr] Re: Working Group Last Call for "Flexible Algorithms: >> Bandwidth, Delay, Metrics and Constraints" - >> draft-ietf-lsr-flex-algo-bw-con-07 >> Hi Shraddha, Ketan, >> I see the new text also includes RFC 3630 and RFC 5305 generic metric >> applicability. Does everyone agree on this? If not, we should discuss the >> pros and cons. >> Thanks, >> Acee >> >> >> >> On Aug 30, 2024, at 01:20, Shraddha Hegde >> <[email protected]> wrote: >> Hi Ketan, >> Thanks for the text. Will incorporate in ver-13 Rgds Shraddha >> Juniper Business Use Only >> From: Ketan Talaulikar <[email protected]> >> Sent: Wednesday, July 31, 2024 12:01 AM >> To: Shraddha Hegde <[email protected]> >> Cc: Acee Lindem <[email protected]>; lsr <[email protected]>; >> [email protected] >> 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, After >> discussing further on this topic during the IETF with some WG members, I see >> that most of this is covered by existing RFCs and we only need to reference >> them. Please find below the suggested text changes that also fix some other >> issues that I found during the closer review of the LSAs. >> Section 2 >> OLD >> 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. >> NEW >> The usage of a generic metric by an individual application is subject to the >> same rules that apply to other link attributes as defined in [RFC9479] >> [RFC9492] [RFC9350]. >> [Rationale: This change references existing specifications for >> alignment.] Section 2.2 OLD >> • sub-TLV of the OSPF Link TLV of OSPF extended Link LSA [RFC7684]. >> • sub-TLV of TE Link TLV (2) of OSPF TE LSA [RFC3630]. >> • sub-TLV of the Router-Link TLV in the E-Router-LSA in OSPFv3 [RFC8362]. >> • sub-sub-TLV of Application-Specific Link Attributes (ASLA) sub-TLV >> [RFC9492]. >> NEW >> • sub-TLV of TE Link TLV (2) of OSPF TE LSA [RFC3630]. >> • sub-TLV of TE Link TLV (2) of OSPFv2 Inter-AS-TE-v2 LSA [RFC5392]. >> • sub-TLV of TE Link TLV (2) of OSPFv3 Intra-Area-TE-LSA [RFC5329]. >> • sub-TLV of TE Link TLV (2) of OSPFv3 Inter-AS-TE-v3 LSA [RFC5392]. >> • sub-TLV of Application-Specific Link Attributes (ASLA) sub-TLV >> [RFC9492] of the OSPFv2 Extended Link TLV [RFC7684]. >> • sub-TLV of Application-Specific Link Attributes (ASLA) sub-TLV >> [RFC9492] of the OSPFv3 Router-Link TLV [RFC8362]. >> [Rationale: There is no application using advertisements as top-level >> sub-TLVs (i.e., outside ASLA) in the OSPFv2 Extended Link TLV or the >> OSPFv3 Router Link TLV – therefore we need to remove them. Added the >> OSPFv3 LSA for RSVP-TE and also for Inter-AS TE links as done for ISIS. >> Clarified for the ASLA advertisements in OSPFv2 and v3 separately. Finally, >> using alphabetical bullets to make it easier to reference in further text >> (same may help for ISIS section as well).] Section 2.2 OLD The Generic >> Metric sub-TLV MAY be advertised multiple times. For a particular metric >> type, the Generic Metric sub-TLV MUST be advertised only once for a link >> when advertised in the OSPF Link TLV of Extended Link LSA, the Link TLV of >> TE LSA and the sub-TLV of the Router-Link TLV in the E-Router-LSA >> Router-Link TLV in OSPFv3. When Generic Metric sub-TLV is advertised as >> sub-sub-TLV of ASLA, it MUST be advertised only once per-application for a >> link. If there are multiple Generic Metric sub-TLVs advertised for a link >> for the same metric type in a received LSA, the first instance MUST be used >> and the subsequent instances MUST be ignored. >> NEW >> The Generic Metric sub-TLV MAY be advertised multiple times. For a >> particular metric type, the Generic Metric sub-TLV MUST be advertised only >> once for a link when advertised as (a) through (d) above. When Generic >> metric sub-TLV is advertised in ASLA, each metric type MUST be advertised >> only once per-application for a link. If there are multiple Generic Metric >> sub-TLVs advertised for a link for the same metric type (and same >> application in case of ASLA) in one or more received LSAs, advertisement in >> the lowest numbered LSA MUST be used and the subsequent instances MUST be >> ignored. >> [Rationale: Alignment with ISIS text.] >> Thanks, >> Ketan >> On Wed, Jul 24, 2024 at 9:20 PM Shraddha Hegde <[email protected]> wrote: >> Hi Ketan, >> Here is the proposed text >> “Generic Metric is a link attribute appears in various TLVs as >> described in the beginning of this section. >> For Flex-algorithm purposes the use of Generic Metric sub-TLV is >> governed by the rules defined in sec 12 of <xref target ='RFC9350'/>. >> For applications such as RSVP-TE when used in packet networks and in >> GMPLS , Generic Metric is used from TE Link TLV of the OSPF TE LSA <xref >> target ='RFC3630'/> >> as described in sec 4 of <xref target ='RFC9492'/>. >> For applications such as SR Policy <xref target ='RFC9652'/>, Generic >> metric >> may be used from TE Link TLV of the OSPF TE LSA <xref target ='RFC3630'/> >> as specified in sec 12.1 of <xref target ='RFC9492'/>” >> Let me know if that works for you. >> Rgds >> Shraddha >> Juniper Business Use Only >> From: Ketan Talaulikar <[email protected]> >> Sent: Tuesday, July 23, 2024 11:29 PM >> To: Acee Lindem <[email protected]> >> Cc: Shraddha Hegde <[email protected]>; lsr <[email protected]>; >> [email protected] >> 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] Hello Shraddha/Authors, >> Checking to see if we can conclude on the text to be added/updated to cover >> the advertisement and usage for applications other than FlexAlgo like >> RSVP-TE and SR Policy. >> Thanks, >> Ketan >> On Mon, May 27, 2024 at 8:27 AM Ketan Talaulikar <[email protected]> >> wrote: >> Hi Acee, >> Please check inline below for responses. >> On Thu, May 23, 2024 at 1:58 AM Acee Lindem <[email protected]> wrote: >> Ketan, >> First of all, the have been early allocations for over almost 2 years now >> and it isn’t very timely to object at the end of WG last call. However, I >> think your concerns can easily be satisfied. >> KT> It is only at WGLC that the authors have indicated that the draft is >> "complete" and therefore the WGLC seems the time for me to object that it >> isn't complete? I agree that my concerns can be easily satisfied with >> additional text - I've shared the suggestions for the same as well. >> On May 21, 2024, at 12:18, Ketan Talaulikar <[email protected]> wrote: >> Hi Acee, >> You seem to have misunderstood my concern. I am not asking for specification >> of the RSVP-TE CSPF algorithm/computation using Generic Metric. >> Let me clarify my objections. There are 3 ways in which Generic Metric can >> be advertised for OSPFv2 as stated in this draft: >> 1) As a sub-TLV of the ASLA sub-TLV in the OSPFv2 Extended Link LSA : For >> FlexAlgo usage this is the one and only one way to advertise Generic Metric >> in OSPFv2 (note there is no L-bit in OSPF for ASLA). RFC 9492 (ASLA) allows >> for this to be used for other applications beyond FlexAlgo. I would like >> this draft to clarify if it is defining Generic Metric use for any >> application other than FlexAlgo under ASLA - see further in my email. >> 2) As a top-level sub-TLV of the OSPFv2 Extended Link TLV in the OSPFv2 >> Extended Link LSA : This document is making allocation in this namespace but >> that is not an issue since the namespace is shared with ASLA. However, the >> draft needs to clarify that it is not defining Generic Metric use for any >> application when advertised this way as it is not used in base OSPF route >> calculation. >> So, basically 1 and 2 are the same and equates to “Generic metric usage for >> applications other than flex algorithm is out of scope. Future documents may >> describe usage.” >> KT> Sure, that was the "easy" option that I had initially suggested. >> However, Shraddha mentioned that she is aware of ongoing/existing >> implementations and that is why I am instead suggesting that we add some >> text to cover those other applications. I don't think it should be very >> difficult to incorporate. >> 3) As a sub-TLV of the Link TLV in the OSPFv2 TE Opaque LSA : This >> document is making an allocation in this namespace but not indicating any >> application usage. If the intention is to use this advertisement for RSVP-TE >> CSPF, then there is no issue since this is allowed per RFC 9492 Section >> 12.3.4. However, the draft must explicitly state that this is the only way >> to use it for RSVP-TE application. >> I’m looking at RFC 9492 Section 12.1 - why couldn’t the generic metric be >> used for the other referenced applications - LFA and SR policy if usage is >> described in a future document? Similar to above. >> KT> For SR Policy, it is certainly possible. For LFA, I am not sure at this >> point other than within FlexAlgo. I would rather prefer that we add small >> sections in the current draft that cover RSVP-TE and SR Policy at least (as >> suggested). I can provide the text if the authors are OK with this proposal. >> Thanks, >> Ketan >> Shraddha - can you provide these application scoping statements? >> Thanks, >> Acee >> Now, in addition to the above, there is the SR Policy CSPF computation >> application (very similar to RSVP-TE) as well and this draft does not >> clarify how Generic Metric is to be advertised for that application. Per >> RFC9492, it should be as (1) and not as (2) or (3). >> Without this clarification, we are in for interop issues for all >> applications other than FlexAlgo. >> Finally, the list of points that I shared earlier on this thread is not >> about the actual CSPF computation algo, but more about the semantics of the >> advertisement itself. >> I hope this clarifies why this draft is currently underspecified for Generic >> Metric TLV usage for all applications other than FlexAlgo. >> Thanks, >> Ketan >> On Sat, May 18, 2024 at 4:19 AM Acee Lindem <[email protected]> wrote: >> On May 17, 2024, at 17:14, Acee Lindem <[email protected]> wrote: >> Hi Ketan, Shraddha, >> On May 17, 2024, at 07:22, Ketan Talaulikar <[email protected]> wrote: >> Hi Shraddha, >> Thanks for your response. I believe we now have only one open discussion >> point and hence I am top posting my suggestions. >> If the authors wish to cover the Generic Metric TLV usage in TE Opaque LSAs >> in this document then we will need more text/specification than "All >> traditional TE applications like CSPF/RSVP make use of link-attributes from >> TE-LSA." >> Since the new Generic Metric code point is in this registry - >> https://urldefense.com/v3/__https://www.iana.org/assignments/ospf-traffic-eng-tlvs/ospf-traffic-eng-tlvs.xhtml*subtlv2__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6FGeDTJ1g$ >> I don’t the issue with it being used for TE applications currently making >> use of the TE Opaque LSA - we’re still using the OSPF TE Opaque LSA for >> traditional TE. Right? >> Some suggestions which can be incorporated in a separate section that is >> titled "Use of Generic Metric for RSVP-TE": >> - specify that Generic Metric TLV usage in TE Opaque LSAs is limited >> to RSVP-TE use >> - specify the differences for use of bandwidth metric for RSVP-TE; I >> assume it is a constant metric value itself since we don't have FAD to >> determine the b/w metric >> - flex algo prunes links w/o the specific metric advertisements; will it be >> the same for RSVP-TE CSPF? >> - cover backward compatibility aspects (e.g., what if the computation >> needs to optimize on a particular metric and a set of routers/links don't >> carry that metric value) I hope this gives an idea of the details necessary >> if this document is attempting to cover use of generic metric for not just >> flex algo but other applications. If there were any other applications/usage >> in mind, it would be good to clarify that explicitly. We have many different >> LSAs in OSPF resulting in potential interop issues if the specifications are >> not clear. >> Perhaps, it should be stated that usage will be specified in future >> documents. This could included in the -13 version with Peter’s comments. >> On second thought, since RSVP signals the complete path, the TE path >> computation typically has not be standardized and I don’t think this is >> required. We can move forward with the -13 version with Peter’s comments. >> Thanks, >> Acee >> Thanks, >> Acee >> Thanks, >> Ketan >> On Thu, May 16, 2024 at 2:56 PM Shraddha Hegde <[email protected] >> <mailto:[email protected]>> wrote: >> Hi Ketan, >> Snipping to open points >> 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. >> KT2> I am not sure this is sufficient. Let us take an example. How is the >> Generic Metric TLV received in OSPFv2 TE Opaque LSA handled and what is it >> used for? >> <SH3> The text in the draft says the applications that make use of link >> attributes from TE LSA will also use generic metric from TE-LSA. All >> traditional TE applications like CSPF/RSVP make use of link-attributes from >> TE-LSA. I don’t see the need to say anything beyond what has already been >> said in the draft. >> The Min Unidirectional Link Delay as advertised by sub-sub-TLV 12 of ASLA >> sub-TLV [RFC8920], 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], 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. >> KT2> Well, that is what I am also trying to point out ... that the draft is >> wrong :-) The one to use is 13 - please check below and let me know if I am >> missing something. I also urge you to stick to using OSPF conventions of >> using TLV names as opposed to the ISIS convention of using TLV numbers. >> Refer: >> https://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc9350.htm >> l*section-5.2__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1r >> Sq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6Fb0HOfOg$ ... look for IGP >> metric type 1 And then: >> https://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc7471*sec >> tion-4.2__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o >> 1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6GnElBzCw$ and >> https://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc8920.htm >> l*section-14.1__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1 >> rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6FRzXEUMw$ >> 12 Unidirectional Link Delay Y [RFC9492] >> 13 Min/Max Unidirectional Link Delay Y [RFC9492] <SH3> Ok I got it. >> Will fix in -12 version >> 7) Regarding >> https://urldefense.com/v3/__https://www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*section-6__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6GV3tj5Xw$ >> , 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. >> KT2> I am not sure I follow and it would help if you can perhaps give an >> example. >> I am fine with whatever WG decides to do. >> I want to hear if anyone in WG has an opinion on adding Appendix. >> KT2> Sure. My point is that this seems like an ordered set of rules that are >> being updated by multiple documents (more to come). How does one keep track >> of the "current" set of rules without some trail or each new(er) document >> capturing the "latest" set? >> <SH3> I don’t see any other opinions on mailing list. Will add appendix in >> -12 with full set of rules. >> Rgds >> Shraddha >> Juniper Business Use Only >> From: Ketan Talaulikar <[email protected] <mailto:[email protected]>> >> Sent: Saturday, April 27, 2024 11:44 AM >> To: Shraddha Hegde <[email protected] <mailto:[email protected]>> >> Cc: Acee Lindem <[email protected] <mailto:[email protected]>>; lsr >> <[email protected] <mailto:[email protected]>>; >> [email protected] >> <mailto:[email protected]> >> 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, Please check >> inline below with KT2. >> On Mon, Apr 15, 2024 at 12:16 PM Shraddha Hegde <[email protected] >> <mailto:[email protected]>> wrote: >> Hi Ketan, >> Thanks for reply. >> Pls see inline.. >> Juniper Business Use Only >> From: Ketan Talaulikar <[email protected] <mailto:[email protected]>> >> Sent: Monday, April 8, 2024 2:25 PM >> To: Shraddha Hegde <[email protected] <mailto:[email protected]>> >> Cc: Acee Lindem <[email protected] <mailto:[email protected]>>; lsr >> <[email protected] <mailto:[email protected]>>; >> [email protected] >> <mailto:[email protected]> >> 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 <[email protected] >> <mailto:[email protected]>> wrote: >> Hi Ketan, >> Thanks for the review and comments. >> Pls see inline for replies. >> Juniper Business Use Only >> From: Ketan Talaulikar <[email protected] <mailto:[email protected]>> >> Sent: Thursday, March 21, 2024 10:07 PM >> To: Acee Lindem <[email protected] <mailto:[email protected]>> >> Cc: lsr <[email protected] <mailto:[email protected]>>; >> [email protected] >> <mailto:[email protected]> >> 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]. 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://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc9350.html*name-max-metric-consideration__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6FSgkt6Sw$ >> 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. >> KT2> I am not sure this is sufficient. Let us take an example. How is the >> Generic Metric TLV received in OSPFv2 TE Opaque LSA handled and what is it >> used for? >> 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://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!C97xg51a >> Rs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6 >> HkMAY7ww$ >> <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], 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], 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. >> KT2> Well, that is what I am also trying to point out ... that the draft is >> wrong :-) The one to use is 13 - please check below and let me know if I am >> missing something. I also urge you to stick to using OSPF conventions of >> using TLV names as opposed to the ISIS convention of using TLV numbers. >> Refer: >> https://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc9350.htm >> l*section-5.2__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1r >> Sq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6Fb0HOfOg$ ... look for IGP >> metric type 1 And then: >> https://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc7471*sec >> tion-4.2__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o >> 1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6GnElBzCw$ and >> https://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc8920.htm >> l*section-14.1__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1 >> rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6FRzXEUMw$ >> 12 Unidirectional Link Delay Y [RFC9492] >> 13 Min/Max Unidirectional Link Delay Y [RFC9492] >> 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. >> KT2> OK - I leave it to you. >> 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://urldefense.com/v3/__https://www.rfc-editor.org/rfc/rfc9350.html*section-5__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6EA172HPw$ >> 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://urldefense.com/v3/__https://www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-bw-con-08.html*section-6__;Iw!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDuwaokekq2DrWukyCtb3iBDfI6GV3tj5Xw$ >> , 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. >> KT2> I am not sure I follow and it would help if you can perhaps give an >> example. >> I am fine with whatever WG decides to do. >> I want to hear if anyone in WG has an opinion on adding Appendix. >> KT2> Sure. My point is that this seems like an ordered set of rules that are >> being updated by multiple documents (more to come). How does one keep track >> of the "current" set of rules without some trail or each new(er) document >> capturing the "latest" set? >> Thanks, >> Ketan >> 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 <[email protected] >> <mailto:[email protected]>> 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 >> [email protected] <mailto:[email protected]> >> https://urldefense.com/v3/__https://www.ietf.org/mailman/listinfo/lsr_ >> _;!!NEt6yMaO-gk!C97xg51aRs4Qmr-9zJwV-vVuuijMIG0ko-sq1rSq38o1QPxRN2LCDu >> waokekq2DrWukyCtb3iBDfI6H6Mq4QsA$ >> _______________________________________________ >> Lsr mailing list -- [email protected] >> To unsubscribe send an email to [email protected] >> _______________________________________________ >> Lsr mailing list -- [email protected] >> To unsubscribe send an email to [email protected] >> _______________________________________________ >> Lsr mailing list -- [email protected] >> To unsubscribe send an email to [email protected] >> _______________________________________________ >> Lsr mailing list -- [email protected] >> To unsubscribe send an email to [email protected] >> _______________________________________________ >> Lsr mailing list -- [email protected] >> To unsubscribe send an email to [email protected] >> _______________________________________________ >> Lsr mailing list -- [email protected] >> To unsubscribe send an email to [email protected] > > > > _______________________________________________ > Lsr mailing list -- [email protected] > To unsubscribe send an email to [email protected]
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