Internet DRAFT - draft-pignataro-opsawg-oam-whaaat-question-mark
draft-pignataro-opsawg-oam-whaaat-question-mark
OPS Area Working Group C. Pignataro
Internet-Draft NC State University
Updates: 6291 (if approved) A. Farrel
Intended status: Best Current Practice Old Dog Consulting
Expires: 23 July 2024 20 January 2024
Guidelines for Charactering "OAM"
draft-pignataro-opsawg-oam-whaaat-question-mark-02
Abstract
As the IETF continues to produce and standardize different
Operations, Administration, and Maintenance (OAM) protocols and
technologies, various qualifiers and modifiers are prepended to the
OAM acronym. While, at first glance, the most used appear to be well
understood, the same qualifier may be interpreted differently in
different contexts. A case in point is the qualifiers "in-band" and
"out-of-band" which have their origins in the radio lexicon and which
have been extrapolated into other communication networks.
This document considers some common qualifiers and modifiers that are
prepended, within the context of packet networks, to the OAM acronym,
and lays out guidelines for their use in future IETF work.
This document updates RFC 6291 by adding to the guidelines for the
use of the term "OAM".
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 23 July 2024.
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Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. In-Band and Out-of-Band OAM . . . . . . . . . . . . . . . . . 3
2.1. Historical Uses . . . . . . . . . . . . . . . . . . . . . 5
3. Active, Passive, Hybrid, and Compound OAM . . . . . . . . . . 5
4. Extended OAM Acronyms . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
It is not uncommon for historical and popular terms to have
fundamental nuances in how they are interpreted or understood. This
was, for example, the case with the acronym for Operations,
Administration, and Maintenance, "OAM", and [RFC6291] provided
guidelines for its use as well as definitions of its constituent
parts.
Characterizations or qualifiers for "OAM" within packet networks
often encounter similar problems, such as with the adjective phrases
"in-band" and "out-of- band". This document considers some common
qualifiers and modifiers that are prepended to the OAM acronym, and
lays out guidelines for their use in future IETF work to achieve
unambiguous characterization.
Additionally, this document recommends avoiding the creation and use
of extended acronyms for the qualifiers of "OAM". For example, the
first "O" in "OOAM" could mean out-of-band, overlay, or something
else.
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This document updates [RFC6291] by adding to the guidelines for the
use of the term "OAM".
2. In-Band and Out-of-Band OAM
Historically, the terms "in-band" and "out-of-band" were used
extensively in telephony signaling [RFC4733] and appear also in radio
communications. In both these cases, there is an actual "Band"
(i.e., a "Channel" or "Frequency") to be within or outside.
While those terms, useful in their simplicity, continued to be
broadly used to mean "within something" and "outside said something",
a challenge is presented for IP communications and packet switch
networks (PSNs) which do not have a "band" per se, and, in fact, has
multiple "somethings" that OAM can go within or outside. A
frequently encountered case is the use of in-band to mean either in-
packet or in-path.
Within the IETF, the terms "in-band" and "out-of-band" cannot be
reliably understood consistently and unambiguously. Context-specific
redefinitions of these terms lack ability to be generalized, and can
be confused by participants from other contexts. More importantly,
the terms are not self-defining any more and cannot be understood by
someone exposed to them for the first time, since there is no "band"
in IP.
The guidance in this document is to avoid the terms "*-band" and
instead find finer-granularity descriptive terms. The definitions
presented in this document are for use in all future IETF documents
that refer to OAM, and the terms "in-band OAM" and "out-of-band OAM"
are not to be used in future documents.
Path: OAM in relation to a path.
Path-Congruent OAM:
The OAM messages follow the exact same path as the observed
data traffic. This was sometimes referred to as "in-band".
Non-Path-Congruent OAM:
The OAM messages do not follow the same path as the observed
data traffic. This was sometimes referred to as "out-of-band".
[RFC6669] gives an example of "Path-Congruent OAM", and further
describes that the OAM Packets "share their fate with data
packets."
Packet: OAM in relation to a user data packet.
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In-Packet OAM:
The OAM messages are carried as part of data traffic. This was
sometimes referred to as "in-band".
Dedicated-Packet OAM:
The OAM messages have their own OAM packets, separate from data
traffic. This was sometimes referred to as "out-of-band".
The MPLS echo request/reply messages [RFC8029] are an example of
"Dedicated-Packet OAM", since they are described as "An MPLS echo
request/reply is a (possibly labeled) IPv4 or IPv6 UDP packet".
In Situ OAM [RFC9197] is an example of "In-Packet OAM", given that
it 'records OAM information within the packet while the packet
traverses a particular network domain. The term "in situ" refers
to the fact that the OAM data is added to the data packets rather
than being sent within packets specifically dedicated to OAM.'
Initially "In Situ OAM" [IETF96-In-Band-OAM] was also referred to
as "In-band OAM", but was renamed due to the overloaded meaning of
"in-band OAM". Further, [RFC9232] also intertwines the terms "in-
band" with "in situ", though [I-D.song-opsawg-ifit-framework]
settled on using "In Situ". Other similar uses, including
[P4-INT-2.1] and [I-D.kumar-ippm-ifa], still use variations of
"in-band", "in band", or "inband".
Packet Treatment: OAM in relation to the treatment of user data
packets, as for example QoS treatment.
Equal-QoS-Treatment OAM:
The OAM packets receive the same QoS treatment as user data
packets. This was sometimes referred to as "in-band".
Different-QoS-Treatment OAM:
The OAM packets receive different QoS treatment as user data
packets. This was sometimes referred to as "out-of-band".
For a case of either "Non-Path-Congruent OAM" or "Different-QoS-
Treatment OAM", [I-D.ietf-detnet-oam-framework] says "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." [I-D.ietf-raw-architecture] uses similar text.
Combined: OAM in relation to multiple criteria. For example, in
relation to both topological congruence and packet treatment.
Examples include [I-D.ietf-detnet-oam-framework] and
[I-D.ietf-raw-architecture].
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[I-D.ietf-detnet-oam-framework] uses Combined OAM when it says
"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". [I-D.ietf-raw-architecture] uses similar
text.
2.1. Historical Uses
There are many examples of "in-band OAM" and "out-of-band OAM" in
published RFCs. While interpreting those, it is important to
understand the semantics of what "band" is a proxy for, and to be
more explicit if those documents are updated. This document does not
change the meaning of any terms in any prior RFCs.
For example, [RFC5085] says "as in-band traffic with the PW's data,
or out-of-band", and "in-band (i.e., following the same data-plane
faith as PW data)". Hence, the term "band" refers to the "Pseudowire
data".
3. Active, Passive, Hybrid, and Compound OAM
[RFC7799] provides clear definitions for active and passive
performance assessment such that the construction of metrics and
methods can be described as either "Active" or "Passive". Even
though [RFC7799] does not include the specific terms "Active",
"Passive", or "Hybrid" as modifiers of "OAM", the following terms are
used in many RFCs and are provided here for use in all future IETF
documents that refer to OAM.
Active OAM:
Depends on dedicated instrumentation OAM packets.
Passive OAM:
Depends solely on the observation of one or more existing data
packet streams, and does not use dedicated OAM packets.
Hybrid OAM:
Uses instrumentation or modification of data packets themselves.
[RFC9341] and [RFC9197] are examples labeled "Hybrid OAM" under
this definition.
Compound OAM:
Uses a combination of at least two of Active OAM, Passive OAM, and
Hybrid OAM (i.e., a combination of atomic OAM packets, data packet
modification for OAM, and no OAM packet). Note that [RFC7799]
also uses the term "Hybrid" to refer to metric types in-between
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active and passive, for OAM there are no in-betweens per se, only
active, passive, hybrid, or a combination.
Compound OAM can further be characterized in a more explicit way,
for nuanced use-cases.
* Active-Passive OAM.
* Active-Hybrid OAM.
* Hybrid-Passive OAM.
* Active-Hybrid-Passive OAM.
[RFC7799] adds to the confusion by describing "passive methods" as
"out of band". Following the guidelines of this document, OAM may be
qualified according to the terms described in Sections 2 and 3 of
this document, and the term "out of band OAM" is not to be used in
future documents.
4. Extended OAM Acronyms
This document recommends avoiding the creation and use of extended
acronyms for the qualifiers of "OAM". For example, the first "O" in
"OOAM" could mean out-of-band, overlay, or something else.
[RFC9197] currently uses the acronym "IOAM" for In Situ Operations,
Administration, and Maintenance. While this document does not
obsolete that acronym, it still recommends that "In situ OAM" is used
instead to avoid potential ambiguity.
5. Security Considerations
Security is improved when the terms used and their definitions are
unambiguous.
6. Acknowledgements
The creation of this document was triggered when observing one of
many on-mailing-list discussions of what these terms mean, and how to
abbreviate them. Participants on that mailing thread include,
alphabetically: Adrian Farrel, Alexander Vainshtein, Florian Kauer,
Frank Brockners, Greg Mirsky, Italo Busi, Loa Andersson, Med
Boucadair, Michael Richardson, Quan Xiong, Stewart Bryant, Tom Petch,
Eduard Vasilenko, and Xiao Min.
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The authors wish to thank Hesham Elbakoury, Michael Richardson,
Stewart Bryant, Greg Mirsky, Med Boucadair, and Loa Andersson for
their review and very useful comments.
7. References
7.1. Normative References
[RFC6291] Andersson, L., van Helvoort, H., Bonica, R., Romascanu,
D., and S. Mansfield, "Guidelines for the Use of the "OAM"
Acronym in the IETF", BCP 161, RFC 6291,
DOI 10.17487/RFC6291, June 2011,
<https://www.rfc-editor.org/info/rfc6291>.
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
7.2. Informative References
[I-D.ietf-detnet-oam-framework]
Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., Bernardos,
C. J., Varga, B., and J. Farkas, "Framework of Operations,
Administration and Maintenance (OAM) for Deterministic
Networking (DetNet)", Work in Progress, Internet-Draft,
draft-ietf-detnet-oam-framework-11, 8 January 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-detnet-
oam-framework-11>.
[I-D.ietf-raw-architecture]
Thubert, P., "Reliable and Available Wireless
Architecture", Work in Progress, Internet-Draft, draft-
ietf-raw-architecture-16, 20 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-raw-
architecture-16>.
[I-D.kumar-ippm-ifa]
Kumar, J., Anubolu, S., Lemon, J., Manur, R., Holbrook,
H., Ghanwani, A., Cai, D., Ou, H., Li, Y., and X. Wang,
"Inband Flow Analyzer", Work in Progress, Internet-Draft,
draft-kumar-ippm-ifa-07, 7 September 2023,
<https://datatracker.ietf.org/doc/html/draft-kumar-ippm-
ifa-07>.
[I-D.song-opsawg-ifit-framework]
Song, H., Qin, F., Chen, H., Jin, J., and J. Shin,
"Framework for In-situ Flow Information Telemetry", Work
in Progress, Internet-Draft, draft-song-opsawg-ifit-
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framework-21, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-song-opsawg-
ifit-framework-21>.
[IETF96-In-Band-OAM]
Brockners, F., Bhandari, S., Dara, S., Pignataro, C.,
Gedler, H., Youell, S., and J. Leddy, "IETF 96, OPSWG: In-
Band OAM", IETF-96 Proceedings, IETF-96 slides-96-opsawg-
8.pdf, 19 July 2016,
<https://www.ietf.org/proceedings/96/slides/slides-96-
opsawg-8.pdf>.
[P4-INT-2.1]
"In-band Network Telemetry (INT) Dataplane Specification,
Version 2.1", 11 November 2020,
<https://p4.org/p4-spec/docs/INT_v2_1.pdf>.
[RFC4733] Schulzrinne, H. and T. Taylor, "RTP Payload for DTMF
Digits, Telephony Tones, and Telephony Signals", RFC 4733,
DOI 10.17487/RFC4733, December 2006,
<https://www.rfc-editor.org/info/rfc4733>.
[RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual
Circuit Connectivity Verification (VCCV): A Control
Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085,
December 2007, <https://www.rfc-editor.org/info/rfc5085>.
[RFC6669] Sprecher, N. and L. Fang, "An Overview of the Operations,
Administration, and Maintenance (OAM) Toolset for MPLS-
Based Transport Networks", RFC 6669, DOI 10.17487/RFC6669,
July 2012, <https://www.rfc-editor.org/info/rfc6669>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[RFC9197] Brockners, F., Ed., Bhandari, S., Ed., and T. Mizrahi,
Ed., "Data Fields for In Situ Operations, Administration,
and Maintenance (IOAM)", RFC 9197, DOI 10.17487/RFC9197,
May 2022, <https://www.rfc-editor.org/info/rfc9197>.
[RFC9232] Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and
A. Wang, "Network Telemetry Framework", RFC 9232,
DOI 10.17487/RFC9232, May 2022,
<https://www.rfc-editor.org/info/rfc9232>.
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[RFC9341] Fioccola, G., Ed., Cociglio, M., Mirsky, G., Mizrahi, T.,
and T. Zhou, "Alternate-Marking Method", RFC 9341,
DOI 10.17487/RFC9341, December 2022,
<https://www.rfc-editor.org/info/rfc9341>.
Authors' Addresses
Carlos Pignataro
North Carolina State University
United States of America
Email: cpignata@gmail.com, cmpignat@ncsu.edu
Adrian Farrel
Old Dog Consulting
United Kingdom
Email: adrian@olddog.co.uk
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