Hi Rebecca Thanks for the updated Auth48 text. I have a couple of comments.
Regards Matthew 1. Introduction: I think PSH in the second sentence should be pluralised: OLD: Examples of PSH include existing artifacts such as control words [RFC4385<https://www.rfc-editor.org/authors/rfc9790.html#RFC4385>], BIER (Bit Index Explicit Replication) headers [RFC8296<https://www.rfc-editor.org/authors/rfc9790.html#RFC8296>] and the like, as well as new types of PSH being discussed by the MPLS Working Group. NEW: Examples of PSHs include existing artifacts such as control words [RFC4385<https://www.rfc-editor.org/authors/rfc9790.html#RFC4385>], BIER (Bit Index Explicit Replication) headers [RFC8296<https://www.rfc-editor.org/authors/rfc9790.html#RFC8296>] and the like, as well as new types of PSH being discussed by the MPLS Working Group. 2.1 Definitions: The definition of PSH is a bit unclear in terms of what it is referring to for the optional field of interest, and it is also mandates that the PSH must include a length when in fact most existing PSHs (such as the PW CW or G-ACH) do not include such a field. I would propose rephrasing to: OLD: Post-Stack Header (PSH): Optional field of interest to the egress Label Switching Router (LSR) (and possibly to transit LSRs). Examples include a control word [RFC4385<https://www.rfc-editor.org/authors/rfc9790.html#RFC4385>] [RFC8964<https://www.rfc-editor.org/authors/rfc9790.html#RFC8964>] or an associated channel [RFC4385<https://www.rfc-editor.org/authors/rfc9790.html#RFC4385>] [RFC5586<https://www.rfc-editor.org/authors/rfc9790.html#RFC5586>] [RFC9546<https://www.rfc-editor.org/authors/rfc9790.html#RFC9546>]. The PSH MUST indicate its length, so that a parser knows where the embedded packet starts. NEW: Post-Stack Header (PSH): A field containing information which may be of interest to the egress Label Switching Router (LSR) or transit LSRs. Examples include a control word [RFC4385<https://www.rfc-editor.org/authors/rfc9790.html#RFC4385>] [RFC8964<https://www.rfc-editor.org/authors/rfc9790.html#RFC8964>] or an associated channel header [RFC4385<https://www.rfc-editor.org/authors/rfc9790.html#RFC4385>] [RFC5586<https://www.rfc-editor.org/authors/rfc9790.html#RFC5586>] [RFC9546<https://www.rfc-editor.org/authors/rfc9790.html#RFC9546>]. A parser needs to be able to determine where the PSH ends in order to find the embedded packet. Best regards, Matthew From: Rebecca VanRheenen <rvanrhee...@staff.rfc-editor.org> Date: Thursday, 15 May 2025 at 22:01 To: Greg Mirsky <gregimir...@gmail.com>, Kireeti Kompella <kireeti.i...@gmail.com>, Stewart Bryant <s...@stewartbryant.com>, Matthew Bocci (Nokia) <matthew.bo...@nokia.com>, Jie Dong <jie.d...@huawei.com>, l...@pi.nu <l...@pi.nu> Cc: RFC Editor <rfc-edi...@rfc-editor.org>, mpls-...@ietf.org <mpls-...@ietf.org>, MPLS Working Group <mpls-cha...@ietf.org>, Adrian Farrel <adr...@olddog.co.uk>, James Guichard <james.n.guich...@futurewei.com>, auth48archive <auth48archive@rfc-editor.org> Subject: Re: AUTH48: RFC-to-be 9790 <draft-ietf-mpls-1stnibble-13> for your review [You don't often get email from rvanrhee...@staff.rfc-editor.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] CAUTION: This is an external email. Please be very careful when clicking links or opening attachments. See the URL nok.it/ext for additional information. Hi Greg and other authors, Greg - Thank you for addressing all of our questions! We have updated the document accordingly. All - Please review the document carefully to ensure satisfaction as we do not make changes once it has been published as an RFC. Contact us with any further updates or with your approval of the document in its current form. We will await approvals from each author prior to moving forward in the publication process. — FILES (please refresh) — Updated XML file: https://www.rfc-editor.org/authors/rfc9790.xml Updated output files: https://www.rfc-editor.org/authors/rfc9790.txt https://www.rfc-editor.org/authors/rfc9790.pdf https://www.rfc-editor.org/authors/rfc9790.html Diff file showing all changes made during AUTH48: https://www.rfc-editor.org/authors/rfc9790-auth48diff.html https://www.rfc-editor.org/authors/rfc9790-auth48rfcdiff.html (side by side) Diff files showing all changes: https://www.rfc-editor.org/authors/rfc9790-diff.html https://www.rfc-editor.org/authors/rfc9790-rfcdiff.html (side by side) https://www.rfc-editor.org/authors/rfc9790-alt-diff.html (diff showing changes where text is moved or deleted) For the AUTH48 status of this document, please see: https://www.rfc-editor.org/auth48/rfc9790 Thank you, RFC Editor/rv > On May 14, 2025, at 4:41 PM, Greg Mirsky <gregimir...@gmail.com> wrote: > > Dear RFC Editor, > thank you for your help in improving this document. Please find my notes > below tagged GIM>>. > > Regards, > Greg > > From: rfc-edi...@rfc-editor.org <rfc-edi...@rfc-editor.org> > Date: Wednesday, 14 May 2025 at 05:24 > To: kireeti.i...@gmail.com <kireeti.i...@gmail.com>, s...@stewartbryant.com > <s...@stewartbryant.com>, Matthew Bocci (Nokia) <matthew.bo...@nokia.com>, > gregimir...@gmail.com <gregimir...@gmail.com>, l...@pi.nu <l...@pi.nu>, > jie.d...@huawei.com <jie.d...@huawei.com> > Cc: rfc-edi...@rfc-editor.org <rfc-edi...@rfc-editor.org>, mpls-...@ietf.org > <mpls-...@ietf.org>, mpls-cha...@ietf.org <mpls-cha...@ietf.org>, > adr...@olddog.co.uk <adr...@olddog.co.uk>, james.n.guich...@futurewei.com > <james.n.guich...@futurewei.com>, auth48archive@rfc-editor.org > <auth48archive@rfc-editor.org> > Subject: Re: AUTH48: RFC-to-be 9790 <draft-ietf-mpls-1stnibble-13> for your > review > > CAUTION: This is an external email. Please be very careful when clicking > links or opening attachments. See the URL nok.it/ext for additional > information. > > > > Authors, > > While reviewing this document during AUTH48, please resolve (as necessary) > the following questions, which are also in the XML file. > > 1) <!-- [rfced] Please note that the abbreviated title of the document has > been > updated as follows. The abbreviated title only appears in the running > header in the pdf output. > > Original: > 1st nibble > > Current: > First Nibble Following Label Stack > GIM>> Thank you; I agree. > --> > > > 2) <!-- [rfced] Please insert any keywords (beyond those that appear in > the title) for use on https://www.rfc-editor.org/search. --> > GIM>> Perhaps > Post-stack header > Load-balancing > > > 3) <!-- [rfced] Please clarify "in the context associated". Note that there > is a similar sentence in the IANA section. > > Original: > Although some existing network > devices may use such a method, it needs to be stressed that the > correct interpretation of the Post-stack First Nibble (PFN) in a PSH > can be made only in the context associated using the control or > management plane with the Label Stack Element (LSE) or group of LSEs > in the preceding label stack that characterize the type of the PSH, > and that any attempt to rely on the value in any other context is > unreliable. > > Perhaps: > Although some existing network > devices may use such a method, it needs to be stressed that the > correct interpretation of the Post-stack First Nibble (PFN) in a PSH > can be made only in the context of using the control or > management plane with the Label Stack Entry (LSE) or group of LSEs > in the preceding label stack that characterizes the type of the PSH. > Any attempt to rely on the value in any other context is > unreliable. > > Or (similar to sentence in IANA section): > Although some existing network > devices may use such a method, it needs to be stressed that the > correct interpretation of the Post-stack First Nibble (PFN) in a PSH > can be made only in the context of the Label Stack Entry (LSE) or group of > LSEs > in the preceding label stack that characterizes the type of the PSH. > Any attempt to rely on the value in any other context is > unreliable. > GIM>> Thank you for your creative options. I will propose another re-wording > using the first option with s/of using/established through/: > Although some existing network > devices may use such a method, it needs to be stressed that the > correct interpretation of the Post-stack First Nibble (PFN) in a PSH > can be made only in the context established through the control or > management plane with the Label Stack Entry (LSE) or group of LSEs > in the preceding label stack that characterizes the type of the PSH. > Any attempt to rely on the value in any other context is > unreliable. --> > > > 4) <!-- [rfced] How may we update the text starting with "including..." to > improve clarity? > > Original: > * To stress the importance that any MPLS packet not carrying plain > IPv4 or IPv6 packets contains a PSH, including any new version of > IP (Section 2.4). > > Perhaps: > * To stress that any MPLS packet not carrying plain > IPv4 or IPv6 packets contains a PSH. This also applies to packets of > any new version of IP (see Section 2.4). > GIM>> Excellent! I agree. > --> > > > 5) <!-- [rfced] The sentences below are from the last two paragraphs of > Section 1. > In the first sentence, will readers understand what is meant by "the > heuristic"? Would it be helpful to add more context, like that included > in the second sentence? > > Original: > Based on the analysis of load-balancing techniques in Section 2.1.1, > this document, in Section 2.1.1.1, introduces a requirement that > deprecates the use of the heuristic and recommends using a dedicated > label value for load balancing. > ... > Furthermore, this document updates [RFC4928] by deprecating the > heuristic method for identifying the type of packet encapsulated in > MPLS. > > Perhaps: > Section 2.1.1 of this document includes an analysis of load-balancing > techniques; based on this, Section 2.1.1.1 introduces a requirement > that deprecates the use of the heuristic method for identifying the type > of packet encapsulated in MPLS and recommends using a > dedicated label value for load balancing. > ... > Furthermore, this document updates [RFC4928] by deprecating this > heuristic method. > GIM>> I like the proposed update of the first paragraph. Since it is followed > by two sentences, would "this heuristic method" reference be clear to a > reader? Would keeping that part unchanged be acceptable? > --> > > > 6) <!-- [rfced] Would you like to alphabetize the list of abbreviations in > Section 1.3 > ("Abbreviations")? Or do you prefer the current order? > > Similarly, would you like to alphabetize the terms in Section 1.2 > ("Definitions") or keep the current order? > GIM>> Yes, alphabetize them, please. > --> > > > 7) <!-- [rfced] We updated this text as shown below. Specifically, we moved > the > third sentence of the first paragraph to follow the list and updated "A." > to read "Example A:". Let us know any concerns. > > Original: > Figure 1 shows an MPLS packet with Layer 2 header X and a label stack > Y ending with Label-n. Then, there are three examples of an MPLS > payload displayed in Figure 2. The complete MPLS packet thus would > consist of [X Y A], or [X Y B], or [X Y C]. > > A. The first payload is a bare IP packet, i.e., no PSH. The PFN in > this case overlaps with the IP version number. > > B. The next payload is a bare non-IP packet; again, no PSH. The PFN > here is the first nibble of the payload, whatever it happens to be. > > C. The last example is an MPLS Payload that starts with a PSH > followed by the embedded packet. Here, the embedded packet could be > IP or non-IP. > > Updated: > Figure 1 shows an MPLS packet with a Layer 2 header X and a label stack > Y ending with Label-n. Figure 2 displays three examples of an > MPLS payload: > > Example A: The first payload is a bare IP packet, i.e., no PSH. The > PFN in this case overlaps with the IP version number. > > Example B: The next payload is a bare non-IP packet; again, no PSH. > The PFN here is the first nibble of the payload, whatever it > happens to be. > > Example C: This example is an MPLS Payload that starts with a PSH > followed by the embedded packet. Here, the embedded packet could > be IP or non-IP. > > Thus, the complete MPLS packet would consist of [X Y A], [X Y B], or > [X Y C]. > GIM>> Thank you for your updates that improve readability of the document. > --> > > > 8) <!-- [rfced] For readability, may we update this list as follows? > > Original: > There are four common ways to load balance an MPLS packet: > > 1. One can use the top label alone. > > 2. One can do better by using all of the non-SPLs (Special Purpose > Labels) [RFC7274] in the stack. > > 3. One can do even better by "divining" the type of embedded packet, > and using fields from the guessed header. The ramifications of > using this load-balancing technique are discussed in detail in > Section 2.1.1.1. > > 4. One can do best by using either an Entropy Label [RFC6790] or a > Flow-Aware Transport (FAT) Pseudowire Label [RFC6391] (see > Section 2.1.1.1). > > Perhaps: > There are four common ways to load balance an MPLS packet: > > 1. Use the top label alone. > > 2. Use all of the non-SPLs (Special Purpose > Labels) [RFC7274] in the stack. This is better than using the > top label alone. > > 3. Divine the type of embedded packet > and use fields from the guessed header. The ramifications of > using this load-balancing technique are discussed in detail in > Section 2.1.1.1. This way is better than the two ways above. > > 4. Use either an Entropy Label [RFC6790] or a > Flow-Aware Transport (FAT) Pseudowire Label [RFC6391] (see > Section 2.1.1.1). This is the best way. > GIM>> I agree with the proposed updates with a suggestion to maintain > quotation marks as "divine". > --> > > > 9) <!-- [rfced] Would including some text to introduce the numbered list in > Section 2.1.1.1 be helpful? If so, please provide the text. > GIM>> I think that the current text is sufficient but I am open to any text > other authors propose. > --> > > > 10) <!-- [rfced] Would it be helpful to update "Support for" to "The framework > for" in this sentence? > > Original: > Support for MPLS Network Actions (MNAs) is described in > [I-D.ietf-mpls-mna-fwk] and is an enhancement to the MPLS > architecture. > > Perhaps: > The framework for MPLS Network Actions (MNAs) is described in [RFC9789] and > is an enhancement to the MPLS architecture. > GIM>> I agree with the proposed change. > --> > > > 11) <!-- [rfced] This sentence notes that the PFN value of 0x0 has two > different > formats, but the IANA registry in Section 3 lists the value 0x0 three > times. Please review and let us know if any updates are needed. > > Original: > This issue is described in section 3.6.1 of [I-D.ietf-mpls-mna-fwk] > and is further illustrated by the PFN value of 0x0 which has two > different formats depending on whether the PSH is a pseudowire > control word or a DetNet control word ... > GIM>> Your observation is correct. Value 0x0 is used by three services that > are listed in the IANA registry in Section 3. But two of these services use > four-octet long format, while one - eight-octet long format. Thus, three > entries in the registry but only two formats. > --> > > > 12) <!-- [rfced] How may we clarify "leading to [RFC4928]"? > > Original: > It was then discovered that > non-IP packets, misidentified as IP when the heuristic failed, were > being badly load balanced, leading to [RFC4928]. > > Perhaps: > It was then discovered that > non-IP packets, misidentified as IP when the heuristic failed, were > being badly load-balanced, leading to the scenario described in [RFC4928]. > GIM>> Thank you for your creative editing! I agree with the proposed update. > --> > > > 13) <!-- [rfced] What does "it" refer to here? > > Original: > It would assist with the progress toward a simpler, more coherent > system of MPLS data encapsulation if the use a PSH for non-IP > payloads encapsulated in MPLS was obsoleted. > > Perhaps: > If the use a PSH for non-IP > payloads encapsulated in MPLS were obsoleted, this would assist with > the progress toward a simpler, more coherent > system of MPLS data encapsulation > > Or: > Obsoleting the use a PSH for non-IP > payloads encapsulated in MPLS would assist with the progress toward a > simpler, more coherent > system of MPLS data encapsulation. > GIM>> Thank you for proposing two excellent options.I slightly prefer the > second with a minor modification (two options ;-) : > s/the use a PSH/the use of a PSH/ or s/the use a PSH/using a PSH/ > --> > > > 14) <!-- [rfced] Please review "to load-balancing MPLS data flows". Should the > "load balance" be used instead of the "load-balancing"? Or > is the current correct? > > Original: > However, before that > can be done, it is important to collect sufficient evidence that > there are no marketed or deployed implementations using the heuristic > practice to load-balancing MPLS data flows. > > Perhaps: > However, before that > can be done, it is important to collect sufficient evidence that > there are no marketed or deployed implementations using the heuristic > practice to load balance MPLS data flows. > GIM>> I think that the current form is acceptable. What do other authors > think? > --> > > > 15) <!-- [rfced] We removed the expansion "Network Service Header" in Table 1 > as > this is expanded previously in the document. If no objections, we will > ask IANA to update the "Post-Stack First Nibble" registry accordingly > prior to publication. > > Link to registry: > https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.iana.org%2Fassignments%2Fpost-stack-first-nibble&data=05%7C02%7Cmatthew.bocci%40nokia.com%7C8f9821d8e9c94a4affb208dd93f38fd0%7C5d4717519675428d917b70f44f9630b0%7C0%7C0%7C638829396764446385%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=gz3KCSRJkFUXqjZhW6jTKBtAxqfOPeeoJY0WaeOwpIk%3D&reserved=0<https://www.iana.org/assignments/post-stack-first-nibble> > > Original: > | NSH | 0x0 | NSH (Network Service Header) > | | | Base Header, payload > > Current: > | NSH | 0x0 | NSH Base Header, paylod > GIM>> I agree; your update makes the table easier to read. > --> > > > 16) <!-- [rfced] Abbreviations > > a) FYI - We updated the expansion for LSE as follows to align with the > expansion used in RFCs-to-be 9789 and 9791. Also, "Label Stack Element" has > not been used in published RFCs. > > Original: > Label Stack Element > > Updated: > Label Stack Entry > GIM>> Great catch, thank you. I agree. > > > b) FYI - We have added expansions for the following abbreviations > per Section 3.6 of RFC 7322 ("RFC Style Guide"). Please review each > expansion in the document carefully to ensure correctness. > > Deterministic Networking (DetNet) > Virtual Private LAN Service (VPLS) > Media Access Control (MAC) > GIM>> Thank you for your thorough work with the document. I agree. > --> > > > 17) <!-- [rfced] Please review the "Inclusive Language" portion of the online > Style Guide <https://www.rfc-editor.org/styleguide/part2/#inclusive_language> > and let us know if any changes are needed. Updates of this nature typically > result in more precise language, which is helpful for readers. > > Note that our script did not flag any words in particular, but this should > still be reviewed as a best practice. > GIM>> Thank you for checking that. I couldn't find anything that raises a red > flag. > --> > > > Thank you. > > RFC Editor/rv > > > > On May 13, 2025, at 9:19 PM, rfc-edi...@rfc-editor.org wrote: > > *****IMPORTANT***** > > Updated 2025/05/13 > > RFC Author(s): > -------------- > > Instructions for Completing AUTH48 > > Your document has now entered AUTH48. 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Kompella, S. Bryant, M. Bocci, G. Mirsky, L. Andersson, > J. Dong > WG Chair(s) : Tarek Saad, Tony Li, Adrian Farrel > > Area Director(s) : Jim Guichard, Ketan Talaulikar, Gunter Van de Velde
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