Re: [Detnet] WG Last Call: draft-ietf-detnet-mpls-oam-08

[Ethan Grossman <[e-mail]>]

Hi Greg,
Based on the draft 9 you sent me, here are my comments. I don't mean to be
"too" picky but I do think these are important to the clarity of the
document.
Ethan.

=================
START
=================

Was:

"[RFC8655] introduces and explains Deterministic Networks (DetNet)
   architecture and how the Packet Replication, Elimination, and
   Ordering functions (PREOF) can be used to ensure low packet drop
   ratio in DetNet domain."


Is:

" ... can be used to ensure low packet drop ratios in a DetNet domain."


(or "can be used to ensure a low packet drop ratio in a DetNet domain.")

============

Was:

   "Operations, Administration, and Maintenance (OAM) protocols are used
   to detect and localize network defects, and to monitor network
   performance.  Some OAM functions (e.g., failure detection) are
   usually performed proactively in the network, while others (e.g.,
   defect localization) are typically performed on demand.  These tasks
   are achieved by a combination of active and hybrid, as defined in
   [RFC7799], OAM methods."


Is:

   " . . .These tasks can be achieved through a combination of active
and hybrid OAM methods, as defined in [RFC7799]."

==============

Was:

"  DetNet Deterministic Networks"

Is:

"  DetNet Deterministic Network"

==============

Was:

   "F-Label A Detnet "forwarding" label that identifies the LSP used to
   forward a DetNet flow across an MPLS PSN, e.g., a hop-by-hop label
   used between label switching routers (LSR)."

Is:

   "F-Label A Detnet "forwarding" label. The F-label identifies the LSP used to
   forward a DetNet flow across an MPLS PSN, e.g., a hop-by-hop label
   used between LSRs"

Also then add to Acronyms section:

"LSR Label Switching Router."

==============

Was:

 "S-Label A DetNet "service" label that is used between DetNet nodes
   that implement also the DetNet service sub-layer functions.  An
   S-Label is also used to identify a DetNet flow at DetNet service sub-
   layer."

Is:

 "S-Label A DetNet "service" label. An S-Label is used between DetNet nodes
   that implement DetNet Service sub-layer functions.  An
   S-Label is also used to identify a DetNet flow within the DetNet
service sub-layer."

(Or maybe consolidate?)

"S-Label A DetNet "service" label. An S-Label identifies a DetNet flow
between DetNet Service nodes within the DetNet service sub-layer."

===============

Was:

"Underlay Network or Underlay Layer: The network that provides

   connectivity between the DetNet nodes.  MPLS network providing LSP
   connectivity between DetNet nodes is an example of the underlay
   layer."

Is:

"Underlay Network or Underlay Layer: The network that provides

   connectivity between DetNet nodes. One example of an underlay

   layer is an MPLS network that provides LSP connectivity between
DetNet nodes."

==============

Was:

   "DetNet Node - a node that is an actor in the DetNet domain.  DetNet
   domain edge node and node that performs PREOF within the domain are
   examples of DetNet node."

Is:

   "DetNet Node - a node that is an actor in the DetNet domain.
Examples of DetNet nodes include DetNet domain Edge nodes, and DetNet
nodes that perform PREOF within the DetNet domain."

===================

Was:

"   OAM protocols and mechanisms act within the data plane of the

   particular networking layer.  And thus it is critical that the data
   plane encapsulation supports OAM mechanisms in such a way to comply
   with the OAM requirements listed in [I-D.tpmb-detnet-oam-framework]."

Is:

"   OAM protocols and mechanisms act within the data plane of the

   particular networking layer, thus it is critical that the data
   plane encapsulation supports OAM mechanisms that comply
   with the OAM requirements listed in [I-D.tpmb-detnet-oam-framework]."

====================

Was:

"   One of such examples that require special consideration is"

Is:

"One such example that requires special consideration is"

===================

Was:

"The Det Net data plane encapsulation in transport network with MPLS

   encapsulation specified in [RFC8964].  For the MPLS underlay network,
   DetNet flows to be encapsulated analogous to pseudowires (PW) over
   MPLS packet switched network, as described in [RFC3985], [RFC4385].
   Generic PW MPLS Control Word (CW), defined in [RFC4385], for DetNet

   displayed in Figure 1."

Is:

 "Operation of a DetNet data plane with an MPLS underlay network is
specified in [RFC8964].  Within the MPLS underlay network, DetNet
flows are to be encapsulated analogous to pseudowires as specified in
[RFC3985] and [RFC4385]. For reference, the Generic PW MPLS CW (as
defined in [RFC4385] and used with DetNet) is reproduced below in
Figure 1."

================

Was:

"   PREOF in the DetNet domain composed by a combination of nodes that

   perform replication and elimination functions.  The elimination
   function always uses the S-Label and packet sequencing information,
   e.g., the value in the Sequence Number field of DetNet CW (d-CW).
   The replication sub-function uses the S-Label information only.  For

   data packets Figure 2 presents an example of PREOF in DetNet domain."

Is:

"   PREOF in the DetNet domain is composed of a combination of nodes that

   perform replication and elimination functions.  The Elimination
sub-function always uses the S-Label in conjunction with the packet
sequencing information (i.e., the Sequence Number encoded in the d-CW). The
Replication sub-function uses the S-Label information only. An example of a
PREOF sequence of operations for data packets in a DetNet domain is shown
in Figure 2."

===============

Was "   DetNet OAM, like PW OAM, uses PW Associated Channel Header defined in

   [RFC4385].  Figure 3 displays the encapsulation of a DetNet MPLS

   [RFC8964] active OAM packet."

Is:

"   DetNet OAM, like PW OAM, uses the PW Associated Channel Header as
defined in [RFC4385]. Encapsulation of a DetNet MPLS [RFC8964] active
OAM packet is shown in Figure 3."

==================

Was:

"   The d-ACH encodes the following fields:


      Bits 0..3 MUST be 0b0001.  This value of the first nibble allows
      the packet to be distinguished from an IP packet [RFC4928] and a

      DetNet data packet [RFC8964]."

Is:

"   The d-ACH encodes the following fields:


      Bits 0..3 MUST be 0b0001.  This value of the first nibble
distinguishes an IP packet [RFC4928] from a DetNet data packet [RFC8964]."

=======================

Was: (all cases like "five-bits field" or "20 bits-long field")

Is: All should be consistent (model from RFC 8964) like "4-bit field"
for all such phrases.

======================

Was: (includes an example of above item)

"      Flags - is a five-bits field.  Flags field contains five one-bit flags."

Is:

"      Flags - 5-bit field containing five 1-bit flags."

=================

Was:

"Flags defined in this specification presented in Figure 6."

Is:

"The flags defined in this specification are presented in Figure 6."

==========

Was:

"Active OAM packet MUST include d-ACH immediately following the S-label."

Is:

"An Active OAM packet MUST include a d-ACH immediately following the S-label."

==============

Was:

"   At the DetNet service sub-layer, special functions MAY be applied to

   the particular DetNet flow, PREOF, to potentially lower packet loss,
   improve the probability of on-time packet delivery and ensure in-
   order packet delivery.  PREOF rely on sequencing information in the
   DetNet service sub-layer.  For a DetNet active OAM packet, 28 MSBs of
   the d-ACH MUST be used as the source of the sequencing information by

   PREOF."

Is:

"   At the DetNet service sub-layer, special functions (notably PREOF)
MAY be applied to the particular DetNet flow to potentially lower
packet loss,

   improve the probability of on-time packet delivery, and ensure in-
   order packet delivery.  PREOF relies on sequencing information in the
   DetNet service sub-layer; for a DetNet active OAM packet, PREOF MUST use
the 28 MSBs of the d-ACH as the source of this sequencing information."

==========

Was:

"   Hybrid OAM methods are used in performance monitoring and defined
in   [RFC7799] as:"

Is:

"   Hybrid OAM methods are used in performance monitoring; they are
defined in   [RFC7799] as:"

===============

Was:

   "A hybrid measurement method may produce metrics as close to passive,
   but it still alters something in a data packet even if that is the
   value of a designated field in the packet encapsulation.  One example
   of such a hybrid measurement method is the Alternate Marking method
   described in [RFC8321].  Reserving the field for the Alternate
   Marking method in the DetNet Header will enhance available to an
   operator set of DetNet OAM tools."

Is:

   "A hybrid measurement method may produce metrics with results that
are close to the results of passive measurement, but it inevitably
alters something in a data packet even if it is only the value of a
designated field in the packet encapsulation.  One example of such a
hybrid measurement method is the Alternate Marking method described in
[RFC8321].  Reserving a field in the DetNet Header for Alternate
Marking can be useful in providing additional options to the
operator-provided set of DetNet OAM tools."

===============

Was:

"   Active DetNet OAM is required to provide the E2E fault management
and    performance monitoring for a DetNet flow. Interworking of
DetNet active OAM with MPLS data plane with the IEEE 802.1
Time-Sensitive Networking (TSN) domain based on [RFC9037]."

Is:

"Active DetNet OAM can be used to provide E2E fault management and
performance monitoring for a DetNet flow. In the case of DetNet with
an MPLS data plane and a TSN underlay network, this implies
interworking of DetNet active OAM with TSN OAM, which is specified in
[RFC9037]."


(Also update TSN definition:

Was:

"   TSN Time-Sensitive Network"

Is:

"   TSN IEEE 802.1 Time-Sensitive Networking"

===============================

Was:

"   In the case of the peering model is used in the fault management OAM,

   then the node that borders both TSN and DetNet MPLS domains MUST
   support [RFC7023].  [RFC7023] specified the mapping of defect states
   between Ethernet Attachment Circuits (ACs) and associated Ethernet
   PWs that are part of an end-to-end (E2E) emulated Ethernet service.
   Requirements and mechanisms described in [RFC7023] are equally
   applicable to using the peering model to achieve E2E FM OAM over
   DetNet MPLS and TSN domains.  The Connectivity Fault Management (CFM)
   protocol [IEEE.CFM] or in [ITU.Y1731] can provide fast detection of a
   failure in the TSN segment of the DetNet service.  In the DetNet MPLS
   domain BFD (Bidirectional Forwarding Detection), specified in
   [RFC5880] and [RFC5885], can be used.  To provide E2E failure
   detection, the TSN segment might be presented as a concatenated with
   the DetNet MPLS and the Section 6.8.17 [RFC5880] MAY be used to
   inform the upstream DetNet MPLS node of a failure of the TSN segment.
   Performance monitoring can be supported by [RFC6374] in the DetNet
   MPLS and [ITU.Y1731] in the TSN domains, respectively.  Performance
   objectives for each domain should refer to metrics that additive or

   be defined for each domain separately."

Is:

"  When the peering model is used in CFM OAM,

   then the node that borders both TSN and DetNet MPLS domains MUST
   support [RFC7023]. [RFC7023] specifies the mapping of defect states
   between Ethernet Attachment Circuits and associated Ethernet
   PWs that are part of an E2E emulated Ethernet service, and are also
applicable to E2E CFM OAM across DetNet MPLS and TSN domains. In the TSN
segment of the DetNet service the CFM protocol ([IEEE.CFM] or [ITU.Y1731])
can provide fast detection of a failure.  In the DetNet MPLS domain, BFD
([RFC5880] and [RFC5885]) can be used.


To provide E2E failure detection, the TSN segment might be presented
as concatenated with the DetNet MPLS, and [RFC5880] Section 6.8.17 MAY
be used to inform the upstream DetNet MPLS node of a failure of the
TSN segment.

   Performance monitoring can be supported by [RFC6374] in the DetNet
   MPLS and [ITU.Y1731] in the TSN domains, respectively.  Performance
   objectives for each domain may refer to metrics that are additive
over the domains, or may be defined for each domain separately."

===================

Was:

"   The following considerations are to be realized when using the

   tunneling model of OAM interworking between DetNet MPLS and TSN

   domains:"

Is:


"   The following considerations apply when using the

   tunneling model of OAM interworking between DetNet MPLS and TSN

   domains:"

===============

Was:

"

   *  Active OAM test packet MUST be mapped to the same TSN Stream ID as

      the monitored DetNet flow."

Is:


"

   *  Active OAM test packets MUST be mapped to the same TSN Stream ID as

      the monitored DetNet flow."

=================

Was:

"   *  Active OAM test packets MUST be treated in the TSN domain based on

      its S-label and CoS marking (TC field value)."

Is:


"   *  Active OAM test packets MUST be treated in the TSN domain based on

      its S-label and CoS marking (TC field value)."

(Maybe existing text is OK, but since you are using MUST here, you
need to add definitions for "CoS" and "TC field value". Presumably CoS
is Class of Service and maybe TC Field is Traffic Control or Traffic
Class?, but a quick google search didn't immediately provide clarity
to me here as to what exactly is being required here).

====================

Was:

"For example, if BFD is

   used for proactive path continuity monitoring in the DetNet MPLS
   domain, a TSN endpoint of the DetNet service has also support BFD as

   defined in [RFC5885]."

Is:

"For example, if BFD is used for proactive path continuity monitoring
in the DetNet MPLS domain, a TSN endpoint of the DetNet service MUST
also support BFD as defined in [RFC5885]."

(Adding a MUST there - is that correct?)

====================

Was:

"To provide the performance monitoring

   over a DetNet IP domain STAMP [RFC8762] and its extensions [RFC8972]

   can be used."

Is:

"To provide performance monitoring over a DetNet IP domain, STAMP
[RFC8762] and its extensions [RFC8972] can be used."

===============

Was:

"This document describes a new IANA-managed registry to identify

   DetNet MPLS OAM Flags Bits. "

Is:

"This document describes a new IANA-managed registry to identify

   DetNet MPLS OAM Flags bits. "

============

Was:

"   Security considerations discussed in DetNet specifications:

   [RFC8655], [RFC9055], [RFC8964] are applicable to this document."

Is:

"   The security considerations discussed in DetNet specifications

   [RFC8655], [RFC9055], [RFC8964] are applicable to this document."

===================

END

===================


On Thu, Oct 13, 2022 at 12:29 PM Greg Mirsky <[e-mail]> wrote:

> Hi Ethan,
> I would greatly appreciate it. I've attached the working version in TXT
> format in case you need it.
>
> Best regards,
> Greg
>
> On Wed, Oct 12, 2022 at 4:33 PM Ethan Grossman <ethan=
> [e-mail]> wrote:
>
>> Hi Greg, do you want me to go through the rest of the (updated) doc at
>> this level of grammatical detail, or do you want to leave it to Editorial?
>> Ethan.
>>
>> On Wed, Oct 12, 2022 at 4:27 PM Greg Mirsky <[e-mail]>
>> wrote:
>>
>>> Hi Ethan,
>>> thank you for your thorough review and very helpful suggestions.  I've
>>> applied all updates to the working version of the draft with a small
>>> modification. I hope that these modifications are acceptable. Please check
>>> the attached diff that highlights all updates suggested by Andy and you.
>>>
>>> Best regards,
>>> Greg
>>>
>>> On Wed, Oct 12, 2022 at 3:15 PM Ethan Grossman <ethan=
>>> [e-mail]> wrote:
>>>
>>>> I have read the document and though I can't comment on the technical
>>>> details of OAM or MPLS I find the document is basically readable and
>>>> understandable. I have a few minor comments on grammar and spelling - I
>>>> suppose such things can be left to Editorial (and at a certain point I
>>>> figured I would stop doing this and let Editorial handle it) but you'll
>>>> have to deal with them eventually. Below are the first few that I noticed.
>>>> Ethan.
>>>> ===============
>>>> Was: "This document defines format and use principals of the
>>>> Deterministic Network (DetNet)"
>>>> Spelling - should be "...use principles..."
>>>>
>>>> Was "Operations, Administration and Maintenance (OAM) protocols are used
>>>>    to detect, localize defects in the network, and monitor network
>>>>    performance."
>>>> Grammar: How about "Operations, Administration and Maintenance (OAM)
>>>> protocols are used
>>>>    to detect and localize defects in the network, and to monitor
>>>> network
>>>>    performance."
>>>>
>>>> Was: "Some OAM functions, e.g., failure detection, work in the network
>>>> proactively, while others, e.g., defect localization,
>>>>    usually performed on-demand."
>>>> Grammar, maybe "Some OAM functions (e.g., failure detection) are
>>>> usually performed proactively in the network, while others (e.g.,
>>>> defect localization) are usually performed on demand."
>>>>
>>>> Was "format and use principals"
>>>> Spelling: "principles"
>>>>
>>>> Was: "Janos Farcas"
>>>> Spelling "Farkas"
>>>> =============
>>>>
>>>>
>>>> On Tue, Oct 11, 2022 at 7:22 AM Janos Farkas <Janos.Farkas=
>>>> [e-mail]> wrote:
>>>>
>>>>> All,
>>>>>
>>>>>
>>>>>
>>>>> This starts working group last call on
>>>>>
>>>>> https://datatracker.ietf.org/doc/draft-ietf-detnet-mpls-oam/
>>>>>
>>>>>
>>>>>
>>>>> The working group last call ends on October 25th.
>>>>>
>>>>> Please send your comments to the working group mailing list.
>>>>>
>>>>>
>>>>>
>>>>> No IPR has been disclosed against this document.
>>>>>
>>>>>
>>>>>
>>>>> Positive comments, e.g., "I've reviewed this document and believe it
>>>>> is ready for publication", are welcome!
>>>>>
>>>>> This is useful and important, even from authors.
>>>>>
>>>>>
>>>>>
>>>>> Thank you,
>>>>>
>>>>> János (DetNet Co-Chair & doc Shepherd)
>>>>> _______________________________________________
>>>>> detnet mailing list
>>>>> [e-mail]
>>>>> https://www.ietf.org/mailman/listinfo/detnet
>>>>>
>>>> _______________________________________________
>>>> detnet mailing list
>>>> [e-mail]
>>>> https://www.ietf.org/mailman/listinfo/detnet
>>>>
>>> _______________________________________________
>>> detnet mailing list
>>> [e-mail]
>>> https://www.ietf.org/mailman/listinfo/detnet
>>>
>> _______________________________________________
>> detnet mailing list
>> [e-mail]
>> https://www.ietf.org/mailman/listinfo/detnet
>>
>