Re: [Detnet] OAM terms

["Pascal Thubert (pthubert)" <[e-mail]>]

Hello Fabrice,

Please see below!

From: detnet <[e-mail]> On Behalf Of Fabrice Theoleyre
Sent: mercredi 7 juillet 2021 8:11
To: Pascal Thubert (pthubert) <[e-mail]>
Cc: [e-mail]; Balázs Varga A <[e-mail]>; Black, David <[e-mail]>; Janos Farkas <[e-mail]>; [e-mail]; DetNet WG <[e-mail]>
Subject: Re: [Detnet] OAM terms

Hi Pascal,

Thanks for taking this initiative.


   [OAM]:  OAM stands for Operations, Administration, and Maintenance, and
      covers the processes, activities, tools, and standards involved
      with operating, administering, managing and maintaining any
      system.  This document uses the terms Operations, Administration,
      and Maintenance, in conformance with the IETF 'Guidelines for the
      Use of the "OAM" Acronym in the IETF' [RFC6291] and the system
      observed by the RAW OAM is the Track.

   Active OAM:  Active OAM uses specially constructed test packets
      crafted to observe a particular Track, subTrack, or Segment of a
      Track.

   In-Band OAM:  An active OAM packet is considered in-band [for] the
      monitored Track when it traverses the same set of links and
      interfaces, [and if the OAM packets receive] the same QoS and PAREO treatment as the data
      flows that are injected in the Track.

   Out-of-Band OAM:  An active OAM packet is out-of-band if its datapath
      is topologically the same as of that of the Track, subTrack or
      Segment being observed, but the QoS or PAREO treatment is
      different (e.g., lower CoS).

   Limited OAM:  An active OAM packet is a Limited OAM packet when it [is]
      observes the RAW operation over a node, a segment, or a subTrack
      of the Track, though not from Ingress to Egress.  It is injected
      in the datapath and extracted from the datapath around the
      particular function or subnetwork (e.g., around a relay providing
      a service layer replication point) that is being tested.



> [FT] I modified directly the text for typos / direct reformulations  [modif]

[PT]  many thanks, I applied


   Reverse OAM:  A Reverse OAM packet is an Out-of-Band OAM packet that
      traverses the Track from West to East and North-South in one of
      either direction, to capture and report OAM measurements upstream.

> [FT] Shall we consider also the case where each intermediary hop reports directly and autonomously the control information to the OAM source? To my mind, saying that an OAM packet collects everything may be quite restrictive, and we may not be able to address all the cases.


[PT]  great point,  what about

    A Reverse OAM packet is an Out-of-Band OAM packet that traverses the Track
    from egress to ingress on the reverse direction, to capture and  report OAM
    measurements upstream. The collection may capture all information along the
    whole Track, or it may only learn select data across all, or only a
     particular subTrack, or Segment of a Track.



[FT] in that case, Reverse OAM: a reverse OAM packet is an Out-of-Band OAM packet that reports OAM measurements from intermediary routers to the OAM source.

[PT]  Well, the PSE may be distributed and learn from incoming reverse OAM at any point in the network.


Keep safe;

Pascal