Hi Andrew, I apologize that the quote came across as confusing. The reference to RFC 7799 is related to the definitions of active and hybrid OAM methods. Yes, I also agree with Matthew that some OAM functions can be used without requiring OAM packets to receive the same QoS treatment from the network as the monitored data flow. Furthermore, for certain OAM functions, such as direct loss measurement, even topological equivalence between the paths traversed by OAM packets and data packets is not required. On the other hand, there are some OAM functions, e.g., active performance measurement, where the combination of the topological and QoS equivalence is necessary to make the observation results most useful to an operator. I hope that makes sense.
Regards, Greg On Thu, Jun 5, 2025 at 7:12 PM Andrew G. Malis <[email protected]> wrote: > Greg, > > I just looked through 7799 and fail to find the terms "in-band", "QoS", or > "quality". Thus I don't see the definition you quoted? from that RFC. > > I also agree with Matthew that there are times when VCCV (or OAM in > general) requires a different QoS treatment in order to work even on the > same physical path through the network, and thus should be left up to the > operator. > > Cheers, > Andy > > > On Wed, Jun 4, 2025 at 9:44 PM Greg Mirsky <[email protected]> wrote: > >> Hi Andy, >> >> Thank you for your thoughtful analysis of not only RFC 5085 but the >> discussion at large. I've pointed to definitions of in-band OAM in RFC >> 9722 <https://datatracker.ietf.org/doc/rfc9772/>: >> >> * In-band OAM is an active or hybrid OAM method, as defined in >> >> [RFC7799], that traverses the same set of links and interfaces and >> >> receives the same Quality of Service treatment as the monitored >> >> object. In this context, the monitored object refers to either >> >> the entire Geneve tunnel or a specific tenant flow within a given >> >> Geneve tunnel. >> >> As you see, the first sentence provides the general definition of in-band >> OAM, while the second clarifies its applicability in the case of Geneve >> environments. Thus, for this discussion, I propose the following: >> >> * In-band OAM is an active or hybrid OAM method, as defined in >> >> [RFC7799], that traverses the same set of links and interfaces and >> >> receives the same Quality of Service treatment as the monitored >> >> object. >> >> If someone is confused about the meaning of "same", it can be replaced >> with "identical" to make it more straightforward. >> >> Regards, >> >> Greg >> >> On Wed, Jun 4, 2025 at 8:48 PM Andrew G. Malis <[email protected]> wrote: >> >>> Hi Med, Carlos, Greg, et al! >>> >>> RFC 5085 doesn't make any reference to QoS treatment as a part of path >>> congruence. It only relies on label equivalence for MPLS PWs and the L2TPv3 >>> session for IP PWs to provide in-band VCCV. >>> >>> Greg does have a point that QoS/traffic class packet forwarding >>> treatment can have an effect on in-band QoS, and I see that is discussed in >>> the characterization draft, but it wasn't included in 5085 as written. >>> >>> So I find the text in the draft to be an accurate quote, except that I >>> wouldn't refer to only section 6. I would either refer to the RFC as a >>> whole, or if you do want section references, I would include sections 3 and >>> 5.1.1 in addition to section 6. >>> >>> However, Greg's comment may not be just about the accuracy of the quote, >>> but not including QoS treatment to ensure path congruence as a part of the >>> definition of in-band OAM. >>> >>> So if my interpretation of Greg's comment is correct, then I would ask >>> Greg to write an alternative example of in-band OAM in prior IETF work that >>> includes QoS treatment to ensure path congruence to include in the draft. >>> >>> Cheers, >>> Andy >>> >>> >>> On Wed, Jun 4, 2025 at 4:48 AM <[email protected]> wrote: >>> >>>> Hi Andy/Stewart/Matthew, >>>> >>>> >>>> >>>> I hope you are doing well. >>>> >>>> >>>> >>>> I’m soliciting your feedback on this text which is included in >>>> draft-ietf-opsawg-oam-characterization: >>>> >>>> >>>> >>>> An example of "Path-Congruent OAM" is the Virtual Circuit >>>> >>>> Connectivity Verification (VCCV), described is Section 6 of >>>> >>>> [RFC5085] as "The VCCV message travels in-band with the Session >>>> >>>> and follows the exact same path as the user data for the session". >>>> >>>> Thus, the term "in-band" in [RFC5085] refers to using the same >>>> >>>> path as the user data. This term is also used in Section 2 of >>>> >>>> [RFC6669] with the same meaning, and the word "congruent" is >>>> >>>> mentioned as synonymous. >>>> >>>> >>>> >>>> Do you see any disconnect between this text and RFC5085? >>>> >>>> >>>> >>>> FWIW, draft-ietf-opsawg-oam-characterization defines “Path-Congruent >>>> OAM” as follows: >>>> >>>> >>>> >>>> The OAM information follows the exact same path as the observed >>>> >>>> data traffic. This was sometimes referred to as "in-band". >>>> >>>> >>>> >>>> Thank you. >>>> >>>> >>>> >>>> Cheers, >>>> >>>> Med >>>> >>>> >>>> >>>> PS: Please see below for more context. >>>> >>>> >>>> >>>> *De :* Greg Mirsky <[email protected]> >>>> *Envoyé :* mercredi 4 juin 2025 07:32 >>>> *À :* Carlos Pignataro <[email protected]> >>>> *Cc :* Ops Area WG <[email protected]> >>>> *Objet :* [OPSAWG]Re: WG LAST CALL: Guidelines for Charactering "OAM" >>>> >>>> >>>> >>>> Hi Carlos, >>>> >>>> please find my notes below tagged GIM2>>. >>>> >>>> >>>> >>>> Regards, >>>> >>>> Greg >>>> >>>> >>>> >>>> On Tue, Jun 3, 2025 at 1:21 AM Carlos Pignataro <[email protected]> >>>> wrote: >>>> >>>> Greg: >>>> >>>> >>>> >>>> While I’ll defer to Tal for a detailed response, I’ve provided three >>>> key points inline. >>>> >>>> See “CMP:” below >>>> >>>> >>>> >>>> On Jun 1, 2025, at 7:49 PM, Greg Mirsky <[email protected]> wrote: >>>> >>>> >>>> >>>> Hi Tal, >>>> >>>> thank you for explaining updates. Please find my follow-up notes below >>>> tagged GIM>>. >>>> >>>> >>>> >>>> Regards, >>>> >>>> Greg >>>> >>>> >>>> >>>> On Thu, May 29, 2025 at 5:59 PM Tal Mizrahi <[email protected]> >>>> wrote: >>>> >>>> Hi Greg, >>>> >>>> Thanks again for reviewing the draft. Your comments for the previous >>>> versions have helped in improving the draft. >>>> Please see my responses to the latest comments that you have sent to >>>> the authors off-list when you kindly reviewed an intermediate version >>>> of the draft. >>>> >>>> >>>> On Tue, May 13, 2025 at 8:38 PM Greg Mirsky <[email protected]> >>>> wrote: >>>> > >>>> > Hi Tal, >>>> > >>>> > Thank you for your work on addressing my comments. I reviewed the >>>> working version of the draft and have some comments and questions, which >>>> are below. >>>> > Section 2: >>>> > >>>> > It is noted that "A frequently encountered case is the use of >>>> "in-band" to mean either in-packet or on-path." If that is the case, and >>>> there are many IETF documents that use these interpretations of "in-band," >>>> it seems like it would be easy to provide several references in support of >>>> that assumption. >>>> >>>> [TM] Following your comment we have focused the following two >>>> paragraphs. >>>> The following paragraph demonstrates the use of the term "in-band" in >>>> the context of path-congruent OAM: >>>> >>>> Connectivity Verification (VCCV), described is Section 6 of >>>> [RFC5085] as "The VCCV message travels in-band with the Session >>>> and follows the exact same path as the user data for the session". >>>> Thus, the term "in-band" in [RFC5085] refers to using the same >>>> path as the user data. This term is also used in Section 2 of >>>> [RFC6669] with the same meaning, and the word "congruent" is >>>> mentioned as synonymous. >>>> >>>> GIM>> I don't think that your interpretation of "in-band" in RFC 5085 >>>> is accurate. The VCCV message not only traverses the same path as a data >>>> packet because the same labels are applied along the path, but it also >>>> receives the same forwarding treatment by the network because the same >>>> Traffic Class is used for the VCCV message as for the data packet. Thus, it >>>> is in-band with the monitored data flow, and topological equivalence is >>>> only one element, while it must be complemented by the QoS equivalence. >>>> >>>> >>>> >>>> CMP: As an author of RFC 5085, I can confirm that you are completely >>>> wrong on this. >>>> >>>> GIM2>> That is your personal opinion, not the opinion of other authors, >>>> and even less the opinion of PWE3 (later PALS) WG. As the PALS WG is >>>> winding down, the MPLS WG may be the community to provide a more >>>> authoritative interpretation of RFC 5085. >>>> >>>> >>>> >>>> CMP: That said, you do not need to be an author to know this, you can >>>> actually **read** the RFC, where it says: >>>> >>>> CMP: *"in-band (i.e., following the same data-plane faith as PW >>>> data).”* >>>> >>>> *CMP: “ travels in-band with the Session and follows the exact >>>> same path as the user data for the session"* >>>> >>>> CMP: Let’s not make up ‘interpretations’. >>>> >>>> >>>> >>>> >>>> >>>> ____________________________________________________________________________________________________________ >>>> 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. Si vous avez >>>> recu ce message par erreur, veuillez le signaler >>>> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages >>>> electroniques etant susceptibles d'alteration, >>>> Orange decline toute responsabilite si ce message a ete altere, deforme ou >>>> falsifie. Merci. >>>> >>>> This message and its attachments may contain confidential or privileged >>>> information that may be protected by law; >>>> they should not be distributed, used or copied without authorisation. >>>> If you have received this email in error, please notify the sender and >>>> delete this message and its attachments. >>>> As emails may be altered, Orange is not liable for messages that have been >>>> modified, changed or falsified. >>>> Thank you. >>>> >>>>
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