Re-, Thanks, Peter. Will update my ballot right now.
Will leave it to you and Gunter about how to track: * Adding draft-ietf-lsr-flex-algo-bw-con to the update list, once published as RFC * Indicating that "experimental algos/attributes are not related to the calculation rules defined in this registry." The first point can be addressed as a note to the RFC Editor. Having a note in the registry would make sense for the second point. Cheers, Med De : Peter Psenak <[email protected]> Envoyé : vendredi 1 août 2025 11:47 À : BOUCADAIR Mohamed INNOV/NET <[email protected]>; The IESG <[email protected]> Cc : [email protected]; [email protected]; [email protected]; [email protected] Objet : Re: Mohamed Boucadair's Discuss on draft-ietf-lsr-igp-flex-algo-reverse-affinity-07: (with DISCUSS and COMMENT) Hi Med, please see inline (##PP): On 01/08/2025 10:48, [email protected]<mailto:[email protected]> wrote: Hi Peter, all, Thank you for the follow-up. I checked 07/10 diff right now. I like where we are heading with these changes. I think the only pending point is this one: " [Med] Thanks for clarifying. The implication is that we need to discuss whether we update RFC9350 and draft-ietf-lsr-flex-algo-bw-con so that the selection steps are now authoritatively offloaded to the registry. ##PP2 sure, I make this document to update RFC9530 " Can we then make that change, please? Thanks. ##PP posted version 11 that has the update for the 9350. Will add the draft-ietf-lsr-flex-algo-bw-con once it's published as RFC. Also, I remember that Les mentioned that the WG wanted to cover Experimental attributes/algos there as well. I think explicitly tagging these as such in the registry would be useful. However, I leave it to decide if you to make the change or not :-) ##PP experimental algos/attributes are not related to the calculation rules defined in this registry. thanks, Peter Cheers, Med De : Peter Psenak <[email protected]><mailto:[email protected]> Envoyé : lundi 14 juillet 2025 11:16 À : BOUCADAIR Mohamed INNOV/NET <[email protected]><mailto:[email protected]>; The IESG <[email protected]><mailto:[email protected]> Cc : [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]> Objet : Re: Mohamed Boucadair's Discuss on draft-ietf-lsr-igp-flex-algo-reverse-affinity-07: (with DISCUSS and COMMENT) Hi Med, please see inline (##PP2): On 08/07/2025 12:11, [email protected]<mailto:[email protected]> wrote: Hi Peter, Thank you for the follow-up. Please see inline. Cheers, Med De : Peter Psenak <[email protected]><mailto:[email protected]> Envoyé : mardi 1 juillet 2025 16:36 À : BOUCADAIR Mohamed INNOV/NET <[email protected]><mailto:[email protected]>; The IESG <[email protected]><mailto:[email protected]> Cc : [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]>; [email protected]<mailto:[email protected]> Objet : Re: Mohamed Boucadair's Discuss on draft-ietf-lsr-igp-flex-algo-reverse-affinity-07: (with DISCUSS and COMMENT) Hi Mohamed, thanks for your comments, please see responses inline (##PP): On 30/06/2025 14:17, Mohamed Boucadair via Datatracker wrote: Mohamed Boucadair has entered the following ballot position for draft-ietf-lsr-igp-flex-algo-reverse-affinity-07: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/about/groups/iesg/statements/handling-ballot-positions/ for more information about how to handle DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-lsr-igp-flex-algo-reverse-affinity/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- Hi Peter, Jakub, and Amit, Thank you for the effort put into this specification. I was surprised that the document does not cite "similar" work on revere metric such as in RFC8500 and RFC9339. I'm not saying this is identical, but there are similarities that are worth to acknowledge. ##PP above mention RFCs alter the local IGP metric from the reverse side of the link. They do that by sending extra data in the protocol Hello packets that overwrite the locally configured metric on the link. What we do in this draft is different. We define a new flex-algo constraint, which is using the link affinities that are set locally on the link. Nothing is sent from the other side of the link that would alter any local link properties. Link affinities are advertised in a traditional way inside the LSA/LSP when the router describe its local links. The new constraint that we defined uses these affinities. On tpp of looking at the affinities in the forward direction of the computation, it is now allowed to look at the link affinities associated with the backward directions of the computation. [Med] Sure. The underlying mechanics differ and, as indicated in my comment I agree that these are not the same. Having some text to position the present work vs these RFCs would be helpful. I won't insist on making any change here as that was a meta comment :-) Please find below some points that I think need to be discussed. # Stability & Lack of Operations Considerations The activation of the attributes defined in this document may have implications on the stability of the routine table. However, the document does not discuss such implications, does not include guards to avoid frequent reverse link updates, does not provide a guidance about how/when it is safe to make an update, does not discuss relevant configuration matters. Worse, the document does only include an example (as part of use case) about how an operator can decide to trigger such message which relies on a threshold-based approach: Section 3: An operator might monitor metrics like CRC errors or other input-related faults at node B and apply thresholds over a defined observation period. If such a threshold is exceeded, node B may locally assign specific Extended Administrative Groups to the link in the direction from B to A. Absent robust hysteresis, it is risky to use such threshold-based approach as this may lead to instability. FWIW, draft-ietf-nmop-terminology rightfully warrant against issues that might be induced by threshold-based schemes: The use of threshold-driven Events and States (and the Alerts that they might give rise to) must be treated with caution to dampen any "flapping" (so that consistent States may be observed) and to avoid overwhelming management processes or systems. ##PP I don't consider RFCs an educational documents, nor implementation guides. RFCs are written to maintain interoperability. [Med] but...safe to use as well. Impact on stability is important for this case. This draft specifies protocol extensions that add additional constraints to the flex-algo computation. It does not even add any new link attribute, it uses an existing one. I don't see why we should talk about how an existing affinity attribute should be set, just because we find a new use case for it. There are many scenarios why an IGP may need to add/remove/modify data in its protocol packets and if not done correctly could impact the stability of the network. Standard mechanisms exists in the IGP protocols to avoid instability caused by the broken originator, whether it is caused by the poor implementation or a bug in it. [Med] Would it harm if you remind these "standard" guards? ##PP2 I can add a simple statement about the stability aspect, but I would rather avoid providing any specific solutions on how to achieve it, as that is not what this document tries to standardize. Please consider adding a discussion to cover these matters. At minimum, a reminder of the considerations in rfc9350#section-15 should be included. ##PP this draft extends the RFC9350. It does not alter section 15 in any way. I do not understand why do you believe we need to mention it here. [Med] As we are extending 9350, we need to check that the ops provisions defined there are altered or not. If there is no implications, let's say so explicitly. Thanks. ##PP2 not sure I got it, do you want to say that "this document does not alter section 15 of RFC9350 "? Are we going to say that for every section of RFC9350 that is not updated? The document already explicitly says which section it updates: "The following procedures augment the rules defined in Section 13 of [RFC9350<https://www.rfc-editor.org/info/rfc9350>] by introducing additional constraints based on Administrative Groups (AGs) associated with the reverse direction of a link." I suggest you also look at rfc8500#section-3.5, rfc9339#section-7, and rfc9339#section-8 to see to what extent the ops considerations discussed out there are relevant in this specific context. ##PP I see no relevance of the above RFCs/sections to what we are specifying here. We do not alter any local link property based on something that we receive from the other side, which is what the above two RFCs do. [Med] ACK # IGP Flex-Algo Path Computation Rules Registry Unless I'm mistaken, this registry is not specific to this specification. What is the rationale for adding this registry here? ##PP This registry is specific to flex-algo technology, that has been defined in RFC9350. Section 13 of that RFC specifies the ordered set of rules that MUST be followed when the algo specific calculation is done. Additional rules have been added by this drat and also by draft-ietf-lsr-flex-algo-bw-con. More changes are on the way. We realized that it would be difficult for people to find the latest set of rules without the centralized registry that keeps track of all changes in these rules. So we created the registry in this draft. Do you see a problem? [Med] Thanks for clarifying. The implication is that we need to discuss whether we update RFC9350 and draft-ietf-lsr-flex-algo-bw-con so that the selection steps are now authoritatively offloaded to the registry. ##PP2 sure, I make this document to update RFC9530 How this registry is intended to be used/maintained? ##PP the same way as any other registry that uses ""Expert Review" registration policy. [Med] :-) My question is more on the practicalities: for example, do we allow DEs to reorder of steps, merge steps, insert a step between existing ones, delete steps, altern a step, etc. ##PP2 we can only do what is backward compatible. We will provide the "guidance" based on the discussion you have had with Les on this thread. Why "Expert Review" is picked as policy for this registry, while all the steps were/are defined in PS documents? Are DEs allowed to delete/modify/merge/reorder steps? What are the implications on already specified metrics? ##PP If you look at all ISIS IANA registries, their registration policy is "Expert Review". Similarly many registries under "Interior Gateway Protocol (IGP) Parameters" use the same policy. I have no issues to change it to SA, but we have been happily using "Expert Review" with IGP registries for many years and it has worked well. [Med] Given the implications on already existing implementations, I think Standard Actions makes sense here. ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- # Illustration examples Consider adding some examples to illustrate the intended use. ##PP what exactly do you want me to illustrate? Is the use case not clearly described? [Med] What I had in mind is an illustrative example with some few routers to show how the procedure is put into effect to ensure path symmetry. Thanks. ##PP2 There is no need for path symmetry here. I still do not understand your ask here. thanks, Peter # Sections 4/5: Simplify as the types are already assigned. OLD: Type (1 octet): An 8-bit field assigned by IANA to uniquely identify the ISIS FAERAG Sub-TLV. Value 10 has been assigned by IANA. NEW: Type (1 octet): 10 ##PP done [Med] Thanks OLD: Type (2 octets): A 16-bit field assigned by IANA to uniquely identify the OSPF FAERAG Sub-TLV. Value 10 has been assigned by IANA. NEW: Type (2 octets): 10 ##PP done [Med] ACK # Section 11.1: Use the correct name of the IANA registry + indicate the registry group OLD: IANA has assigned the following Sub-Sub-TLVs in the "ISIS Sub-Sub- TLVs for Flexible Algorithm Definition Sub-TLV" registry: NEW: IANA has assigned the following Sub-Sub-TLVs in the " IS-IS Sub-Sub-TLVs for Flexible Algorithm Definition Sub-TLV" registry under "IS-IS TLV Codepoints" registry group: ##PP done [Med] ACK # Section 11.2: Use the correct name of the IANA registry + indicate the registry group OLD: IANA has assigned the following Sub-TLVs in the "OSPF TLVs for Flexible Algorithm Definition TLV" registry: NEW: IANA has assigned the following Sub-TLVs in the " OSPF Flexible Algorithm Definition TLV Sub-TLVs" registry under "Open Shortest Path First (OSPF) Parameters" registry group: ##PP done [Med] ACK # Section 11.2: nit OLD: Description: Flexible Algorithm Include-All ReverseAdmin Group NEW: Description: Flexible Algorithm Include-All Reverse Admin Group ##PP fixed [Med] Thanks. thanks, Peter Cheers, Med ____________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. 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