Re: [ippm] [OPSAWG] New I-D -> Guidelines for Charactering "OAM"

   - Hi Carlos and Adrian,

thank you for starting this work. I believe that having a common dictionary
helps in having more productive discussions. I took the liberty of inviting
all the WGs which you invited to review the document and added DetNet WG.
Please feel free to trim the distribution list.
I've read the document and have several general questions to start our
discussion:

   - It seems that the motivation of this document is the assumption that
   "in-band OAM" and "out-of-band OAM" are not representative or cannot be
   understood or correctly attributed, interpreted by the IETF community. Is
   that correct?
   - As we discuss and try to establish (change) the IETF dictionary, it is
   important to analyze the terminology used by other SDOs. I believe that it
   is beneficial to maintain consistent terminology which will minimize
   misunderstandings among experts with different experiences of working at
   different centers of technological expertise.
   - I that DetNet OAM Framework
   <https://datatracker.ietf.org/doc/draft-ietf-detnet-oam-framework/>
   provides sufficiently clear interpretation of terms that can be generalized
   for non-DetNet networks:

   *  In-band OAM is an active OAM that is in-band within the monitored
      DetNet OAM domain when it traverses the same set of links and
      interfaces receiving the same QoS and Packet Replication,
      Elimination, and Ordering Functions (PREOF) treatment as the
      monitored DetNet flow.

   *  Out-of-band OAM is an active OAM whose path through the DetNet
      domain is not topologically identical to the path of the monitored
      DetNet flow, or its test packets receive different QoS and/or
      PREOF treatment, or both.

As can be seen, the interpretation of "in-band" accepted by the DetNet WG
includes not only topological equivalence between the monitored data flow
and path traversed by active OAM but also QoS equivalence between them. I
believe that is essential in differentiating in-band OAM from out-of-band
OAM.

   - I find the use of "path congruence" in inherently meshed
   packet-switched networks confusing if not misleading. (Note that RFC 6669
   <https://www.rfc-editor.org/rfc/rfc6669> explains congruence by using
   in-band term.) Is there evidence of the term being used besides a single
   case in RFC 6669?
   - Similarly, "in-packet" vs. "dedicated packet". I believe that RFC 7799
   <https://www.rfc-editor.org/rfc/rfc7799> has that addressed by using
   "active", "passive", and "hybrid" terminology. Although these terms applied
   to measurement methods, i.e., performance monitoring component of OAM, but,
   in my opinion, can be extended to fault management OAM.
   - It seems like the definition of Compound/Combined misses the point
   that RFC 7799 already defines a hybrid measurement method (not OAM but
   measurement methods) as a method in which elements of active and
   passive measurement methods are used. Hence, hybrid is already a
   combination of active and passive measurement methodologies and the
   introduction of compound or combined terms is unnecessary, a duplication of
   the existing and accepted terminology (at least in IPPM WG). And
   "Active-Hybrid-Passive OAM" is the result of that omission because,
   according to the definition in RFC 7799, Active-Passive is Hybrid. Thus,
   Active-Hybrid-Passive is nothing else but Hybrid-Hybrid. Does that make
   sense?
   - I cannot agree that RFC 7799 "adds to the confusion" by pointing that

   Passive performance metrics are assessed independently of the packets
   or traffic flows, and solely through observation.  Some refer to such
   assessments as "out of band".

Indeed, passive measurement methods are not required to use packets that
are in-band with the monitored data flow. Usually, the management plane
protocol is used to collect, to perform the observation function. In some
cases, in-band active OAM packets may be used, e.g., direct loss
measurement in ETH-OAM.

FWIW, I believe that RFC 7799 and DetNet OAM Requirements already provide a
clear terminology for OAM in general and its elements, i.e., Fault
Management and Performance Monitoring.

Regards,
Greg

On Fri, Jan 5, 2024 at 12:39 PM Carlos Pignataro <cpignata@gmail.com> wrote:

> Hi, Ops Area WG,
>
> Every now and again, there are discussions on how to best characterize or
> qualify a particular kind of "OAM", as well as misunderstandings due to
> having different definitions and contexts for a given term. A case in point
> is "in-band" or "out-of-band" OAM, as recently surfaced at
> https://mailarchive.ietf.org/arch/msg/opsawg/jREEH1sFOZ-uxZNky-RTggpxkuk/.
>
> To alleviate this issue, Adrian and I wrote a short I-D to provide
> forward-looking guidance on "foobar OAM".
>
> We would appreciate feedback and input on this position, which aims at
> updating the guidelines for the "OAM" acronym, with unambiguous guidelines
> for their modifiers.
>
> Guidelines for Charactering "OAM":
>
> https://datatracker.ietf.org/doc/draft-pignataro-opsawg-oam-whaaat-question-mark/
>
> Look forward to input and comments to make this more clear and effective!
>
> Adrian & Carlos.
>
>
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