Framework and Requirements for Ethernet VPN (EVPN) Operations, Administration, and Maintenance (OAM)
draft-ietf-bess-evpn-oam-req-frmwk-10

[Ballot comment]
Here's the text of my previously-a-discuss for reference:

Section 2.3:

  EVPN Network OAM mechanisms MUST provide in-band monitoring
  capabilities. As such, OAM messages MUST be encoded so that they
  exhibit identical entropy characteristics to data traffic in order
  that they share the same fate.

It’s not obvious to me what you mean by “identical entropy characteristics to data traffic”. Surely, different flows may have different entropy characteristics, so, *which* data traffic? Similarly, with which data traffic are you saying the OAM messages must share fate?

Donald proposed:

How about something more like:
EVPN Network OAM mechanisms MUST provide in-band monitoring capabilities. OAM messages SHOULD be encoded so that they exhibit similar entropy characteristics to data traffic in order maximize the fate sharing between OAM and data.

That's fine. (s/in order maximize/in order to maximize/)

I'm switching to "no objection" in anticipation of the document being updated.

Previous comment:

Thanks for the clear and readable document. I have one nit and one question.

1. Section 1, nit:

“EVPN is an Layer 2” s/an/a/

[Ballot comment]
Hi,

Thanks for this document.

It's a bit unclear to me whether the descriptions/definitions of MIP/MEP/MA/MD are coming from CFM or RFC 6136.  Section 1.1 suggests that they are coming from CFM (but without a normative reference to 802.1Q), but the terminology implies that they are being taken from RFC 6136.
Certainly, there seem to be places in this document where more meaning of these terms seems to be expected than what is provided in the terminology section.  Section 2.6 refers to CCMs, but I think that a reader would only understand what these are if they have read CFM.  Hence, I think that this document would probably benefit from having a normative reference to 802.1Q rather than informative.

Minor comments:

    2.1 OAM Layering

    "and shows which devices have visibility into what OAM layer(s)."

Perhaps indicate by the 'o' symbol. Otherwise the fact that the Link OAM is the end point of the physical links, whereas the other OAM endpoints are may cause confusion.

Figure 2:
- Would it be helpful to move the 'o' marks to the end of the PE devices, to line up with the Link OAM end points?

- Is "Service CFM" the right term here?  Does this mean "Service OAM - CFM"?

- Probably helpful to add an informative reference to 802.3 Link OAM, which is in figure 2.

2.2 EVPN Service OAM

- I'm not sure how clear "towards the device" is when the point is already within the device.

- The up and down arrows for the MEPS ("^" and "V") seem to potentially make Figure 3 more confusing.  Also "down" should be changed to "Down" in the last CE.

Nits:

I'm not sure why the PE nodes are numbered by CE nodes are not.

Regards,
Rob

[Ballot comment]
Hi,

Thanks for this document.

It's a bit unclear to me whether the descriptions/definitions of MIP/MEP/MA/MD are coming from CFM or RFC 6136.  Section 1.1 suggests that they are coming from CFM (but without a normative reference to 802.1Q), but the terminology implies that they are being taken from RFC 6136.
Certainly, there seem to be places in this document where more meaning of these terms seems to be expected than what is provided in the terminology section.  Section 2.6 refers to CCMs, but I think that a reader would only understand what these are if they have read CFM.  Hence, I think that this document would probably benefit from having a normative reference to 802.1Q rather than informative.

Minor comments:

    2.1 OAM Layering

    "and shows which devices have visibility into what OAM layer(s)."

Perhaps indicate by the 'o' symbol. Otherwise the fact that the Link OAM is the end point of the physical links, whereas the other OAM endpoints are may cause confusion.

Figure 2:
- Would it be helpful to move the 'o' marks to the end of the PE devices, to line up with the Link OAM end points?
- Is "Service CFM" the right term here?  Does this mean "Service OAM - CFM"?
- Probably helpful to add an informative reference to 802.3 Link OAM, which is in figure 2.

2.2 EVPN Service OAM

- I'm not sure how clear "towards the device" is when the point is already within the device.
- The up and down arrows for the MEPS ("^" and "V") seem to potentially make Figure 3 more confusing.  Also "down" should be changed to "Down" in the last CE.

Nits:

I'm not sure why the PE nodes are numbered by CE nodes are not.

Regards,
Rob

[Ballot comment]
Thank you to Melinda Shore for the SECDIR review.

Section 4.  Since Section 2.2 described a process where the “EVPN PE MUST learn the MAC address of locally attached CE MEPs by snooping on CFM frames ...”, is there is reason not to add the DoS caution from [RFC4762] of “Some means to limit the number of MAC addresses ... that a PE can learn SHOULD be implemented.”

[Ballot discuss]
Section 2.3:

  EVPN Network OAM mechanisms MUST provide in-band monitoring
  capabilities. As such, OAM messages MUST be encoded so that they
  exhibit identical entropy characteristics to data traffic in order
  that they share the same fate.

It’s not obvious to me what you mean by “identical entropy characteristics to data traffic”. Surely, different flows may have different entropy characteristics, so, *which* data traffic? Similarly, with which data traffic are you saying the OAM messages must share fate?

[Ballot comment]
Thanks for the clear and readable document. I have one nit and one question.

1. Section 1, nit:

“EVPN is an Layer 2” s/an/a/

[Ballot comment]
Thanks for the clear and readable document. I have one nit and one question.

1. Section 1, nit:

“EVPN is an Layer 2” s/an/a/

2. Section 2.3:

  EVPN Network OAM mechanisms MUST provide in-band monitoring
  capabilities. As such, OAM messages MUST be encoded so that they
  exhibit identical entropy characteristics to data traffic in order
  that they share the same fate.

It’s not obvious to me what you mean by “identical entropy characteristics to data traffic”. Surely, different flows may have different entropy characteristics, so, *which* data traffic? Similarly, with which data traffic are you saying the OAM messages must share fate?

[Ballot comment]
Thanks for the document and thanks to David Black for TSVART review.

Nits/comments:

* P-MAC and C-MAC are these defined somewhere else? References would be nice here.

* Section 1.3,  Section 2.1 and Section 2.2 describes P nodes in different ways and that has created confusion to me. Can this be well defined in the terminology section once and just be used in other place?

* Section 2.5 : "[802.3]" is this supposed to be a reference? it leads to nowhere.

* Section 3.1.1.2.1 : first time encountered "network management station (NMS)", if this document is not introducing it then I would suggest to at this to section 1.3 and add some descriptive texts, otherwise define it.

* Section 3.1.2.1 : would be nice to expand MTU.

* Section 3.2.1: I  can't really parse - "EVPN Network OAM SHOULD provide mechanisms for measuring packet loss for a given service [RFC7680] [RFC6673]." are these IPPM mechanisms recommended to be used for EVPN networks? or are those merely examples?

[Ballot comment]
Thanks for the document and thanks to David Black for TSVART review.

Nits/comments:

* P-MAC and C-MAC are these defined somewhere else? References would be nice here.

* Section 1.3,  Section 2.1 and Section 2.2 describes P nodes in different ways and that has created confusion to me. Can this be well defined in the terminology section once and just be used other place?

* Section 2.5 : [802.3] is this supposed to be a reference? it leads to no where.

* Section 3.1.1.2.1 : first time encountered "network management station (NMS)", if this document is not introducing it then I would suggest to at this to section 1.3 and add some descriptive texts.

* Section 3.1.2.1 : would be nice to expand MTU.

* Section 3.2.1: I  can't really parse - "EVPN Network OAM SHOULD provide mechanisms for measuring packet loss for a given service [RFC7680] [RFC6673]." are these IPPM mechanisms recommended to be used for EVPN networks? or are those merely examples?

[Ballot comment]
Thanks for the document and thanks to David Black for TSVART review.

Nits/comments:

* P-MAC and C-MAC are these defines somewhere else? References would be nice here.

* Section 1.3,  Section 2.1 and Section 2.2 describes P nodes in different ways and that has created confusion to me. Can this be well defined in the terminology section once and just be used other place?

* Section 2.5 : [802.3] is this supposed to be a reference? it leads to no where.

* Section 3.1.1.2.1 : first time encountered "network management station (NMS)", if this document is not introducing it then I would suggest to at this to section 1.3 and add some descriptive texts.

* Section 3.1.2.1 : would be nice to expand MTU.

* Section 3.2.1: I  can't really parse - "EVPN Network OAM SHOULD provide mechanisms for measuring packet loss for a given service [RFC7680] [RFC6673]." are these IPPM mechanisms recommended to be used for EVPN networks? or are those merely examples?

[Ballot comment]
Thank you for the work put into this document.

Please find below some non-blocking COMMENT points (but replies would be appreciated).

I hope that this helps to improve the document,

Regards,

-éric

== COMMENTS ==

Minor regret for a doc shepherd write-up, which is dated 9 months ago...

-- Section 1 --
Introducing C-MAC and B-MAC could be useful for the reader.

-- Section 1.3 --
Slighlty puzzled by MA/MEP/MIP as those are only about the M of OAM. Should those be OAMA, OAMEP, OAMIP ? Or at least should there be some explanations ?

-- Section 2.2 --
I must confess my lack of knowledge about CFM frames but I am puzzled by "snooping on CFM frames and advertising them to remote PEs as a MAC/IP"
1) if the CFM frame are not IP, then how can it be advertised in a MAC/IP ? (i.e., the CE may not use IP at all)
2) if the CFM frame are IP, then which version of IP ? and how to recognize them ?
Or did I miss something obvious ?

-- Section 3.1.2.1 --
Does this section cover OAM designed by other WG ? E.g., draft-ietf-ippm-ioam-data or draft-ietf-6man-ipv6-alt-mark

-- Section 3.2.1 --
Mostly the same comment as for 3.1.2.1, this section is only about synthetic traffic injection.

[Ballot comment]
All comments below are very minor change suggestions that you may choose to
incorporate in some way (or ignore), as you see fit. There is no need to let me
know what you did with these suggestions.

The following URLs in the document failed to return content:
* http://www.ietf.org/1id-abstracts

[Ballot comment]
[ section 2.4 ]

* Up to you if you want to include ICMPv6 [RFC4443] in the list of
  applicable mechanism.

  =)

[ section 3.1.1.2+ ]

* I can't tell what the mandatory to implement behaviour is.  3.1.1.2 says
  that implementations MUST support event-driven defect indication which
  can be categorized into two types.

  Both types say they SHOULD be supported.  If the overall behaviour is
  a MUST, shouldn't one of these be MTI?  Or is that not important and the
  point is that any implementation MUST choose at least one to support?

[Ballot comment]
Thanks to David Black for the tsvart review, and for the authors addressing his comments.

Sec 2.2 It would help to define "up" and "down" connections.

Sec 3.2.1 & 3.2.2. I am not sure of the extent which IPPM metrics and methods can apply to these layers. But there are some references that can guide loss, delay, and jitter measurements:

Loss: RFC 7680, RFC 6673

Delay: RFC 7679, RFC 2681

Jitter: RFC 3393

I encourage the authors to peruse IPPM's published RFCs on datatracker to see if other documents would be similarly useful.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has reviewed draft-ietf-bess-evpn-oam-req-frmwk-04, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any registry actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, we do not object.

If this assessment is not accurate, please respond as soon as possible.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2021-02-16):

From: The IESG
To: IETF-Announce
CC: Matthew Bocci , bess-chairs@ietf.org, bess@ietf.org, draft-ietf-bess-evpn-oam-req-frmwk@ietf.org, martin.vigoureux@nokia.com, matthew.bocci@nokia.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (EVPN Operations, Administration and Maintenance Requirements and Framework) to Informational RFC


The IESG has received a request from the BGP Enabled ServiceS WG (bess) to
consider the following document: - 'EVPN Operations, Administration and
Maintenance Requirements and
  Framework'
  as Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2021-02-16. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This document specifies the requirements and reference framework for
  Ethernet VPN (EVPN) Operations, Administration and Maintenance (OAM).
  The requirements cover the OAM aspects of EVPN and PBB-EVPN.  The
  framework defines the layered OAM model encompassing the EVPN service
  layer, network layer and underlying Packet Switched Network (PSN)
  transport layer.





The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-oam-req-frmwk/



No IPR declarations have been submitted directly on this I-D.

Document shepherd writeup for draft-ietf-bess-evpn-oam-frmwk-04

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)? Why is
this the proper type of RFC? Is this type of RFC indicated in the title
page header?

Informational. This is properly indicated in the header.


(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary:

This document specifies the requirements and reference framework for
  Ethernet VPN (EVPN) Operations, Administration and Maintenance (OAM).
  The requirements cover the OAM aspects of EVPN and PBB-EVPN.  The
  framework defines the layered OAM model encompassing the EVPN service
  layer, network layer and underlying Packet Switched Network (PSN)
  transport layer.

Working Group Summary:

EVPN is an becoming widely adopted as a technology for implementing layer 2 VPNS.
OAM is required to aid in the maintenance of EVPN and to make it deployable
by service providers. There is strong consensus that this work is required by the BESS
working group, and this draft is required to set the context for determining the
applicability of existing OAM protocols or making extensions or indeed defining new ones.
Theer was no particularly controversial aspects to the draft.

Document Quality:

EVPN is widely implemented and deployed. This draft is an informational set of
requirements and a framework to guide the development of OAM for EVPN and as such
does not require implementations in its own right, yet.

The draft received a number of comments during WG last call which were addressed.

I have no concerns about the quality of the document.

Personnel:

Document Shepherd: Matthew Bocci (matthew.bocci@nokia.com)
Responsible Area Director: Martin Vigoureux (martin.vigoureux@nokia.com)

(3) Briefly describe the review of this document that was performed by
the Document Shepherd. If this version of the document is not ready for
publication, please explain why the document is being forwarded to the
IESG.

I reviewed Version 3 of the draft. I had a few minor editorial comments which
were addressed in Version 4.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

No concerns. The draft was reviewed by a number of participants during WG last call
and comments addressed.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that took
place.

No formal reviews required.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No specific concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why?

Yes.


(8) Has an IPR disclosure been filed that references this document? If
so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

No disclosures.

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others being
silent, or does the WG as a whole understand and agree with it?

There is solid consensus behind the daft. There were a significant number
of participants who indicated support during WG LC who are not co-authors.


(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

None indicated.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.


ID nits passes.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, YANG Doctor, media type, and URI type
reviews.

No formal review requirements.

(13) Have all references within this document been identified as either
normative or informative?

Yes


(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

All normative references are to published RFCs.


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

No

(16) Will publication of this document change the status of any existing
RFCs? Are those RFCs listed on the title page header, listed in the
abstract, and discussed in the introduction? If the RFCs are not listed
in the Abstract and Introduction, explain why, and point to the part of
the document where the relationship of this document to the other RFCs
is discussed. If this information is not in the document, explain why
the WG considers it unnecessary.

This document does not require a change to the status of any existing document.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 8126).


There are no IANA actions.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful
in selecting the IANA Experts for these new registries.

None

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, YANG modules,
etc.

There are no sections written in a formal language.

(20) If the document contains a YANG module, has the module been checked
with any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings,
what is the justification for not fixing them at this time? Does the
YANG module comply with the Network Management Datastore Architecture
(NMDA) as specified in RFC8342?

The document does not define any YANG modules.

Document shepherd writeup for draft-ietf-bess-evpn-oam-frmwk-04

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)? Why is
this the proper type of RFC? Is this type of RFC indicated in the title
page header?

Informational. This is properly indicated in the header.


(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary:

This document specifies the requirements and reference framework for
  Ethernet VPN (EVPN) Operations, Administration and Maintenance (OAM).
  The requirements cover the OAM aspects of EVPN and PBB-EVPN.  The
  framework defines the layered OAM model encompassing the EVPN service
  layer, network layer and underlying Packet Switched Network (PSN)
  transport layer.

Working Group Summary:

EVPN is an becoming widely adopted as a technology for implementing layer 2 VPNS.
OAM is required to aid in the maintenance of EVPN and to make it deployable
by service providers. There is strong consensus that this work is required by the BESS
working group, and this draft is required to set the context for determining the
applicability of existing OAM protocols or making extensions or indeed defining new ones.
Theer was no particularly controversial aspects to the draft.

Document Quality:

EVPN is widely implemented and deployed. This draft is an informational set of
requirements and a framework to guide the development of OAM for EVPN and as such
does not require implementations in its own right, yet.

The draft received a number of comments during WG last call which were addressed.

I have no concerns about the quality of the document.

Personnel:

Document Shepherd: Matthew Bocci (matthew.bocci@nokia.com)
Responsible Area Director: Martin Vigoureux (martin.vigoureux@nokia.com)

(3) Briefly describe the review of this document that was performed by
the Document Shepherd. If this version of the document is not ready for
publication, please explain why the document is being forwarded to the
IESG.

I reviewed Version 3 of the draft. I had a few minor editorial comments which
were addressed in Version 4.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

No concerns. The draft was reviewed by a number of participants during WG last call
and comments addressed.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that took
place.

No formal reviews required.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

No specific concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why?

Yes.


(8) Has an IPR disclosure been filed that references this document? If
so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

No disclosures.

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others being
silent, or does the WG as a whole understand and agree with it?

There is solid consensus behind the daft. There were a significant number
of participants who indicated support during WG LC who are not co-authors.


(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

None indicated.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.


ID nits passes.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, YANG Doctor, media type, and URI type
reviews.

No formal review requirements.

(13) Have all references within this document been identified as either
normative or informative?

Yes


(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

All normative references are to published RFCs.


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

No

(16) Will publication of this document change the status of any existing
RFCs? Are those RFCs listed on the title page header, listed in the
abstract, and discussed in the introduction? If the RFCs are not listed
in the Abstract and Introduction, explain why, and point to the part of
the document where the relationship of this document to the other RFCs
is discussed. If this information is not in the document, explain why
the WG considers it unnecessary.

This document does not require a change to the status of any existing document.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 8126).


There are no IANA actions.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful
in selecting the IANA Experts for these new registries.

None

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, YANG modules,
etc.

There are no sections written in a formal language.

(20) If the document contains a YANG module, has the module been checked
with any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings,
what is the justification for not fixing them at this time? Does the
YANG module comply with the Network Management Datastore Architecture
(NMDA) as specified in RFC8342?

The document does not define any YANG modules.