Definition of P2MP PW TLV for Label Switched Path (LSP) Ping Mechanisms
draft-ietf-pals-p2mp-pw-lsp-ping-05

[Ballot comment]
* I think the P2MP Pseudowire Sub-TLV in Section 4.1 is a bit under-specified. It is unclear how the address family of the originating router's IP address is communicated. Is this purely derived from the IP Addr Len (i.e. Len is 4 => IPv4, Len is 16 => IPv6)? If so, I think it would be useful to state this explicitly and add some validity checking and error handling for values other than 4 and 16. [Authors clarified that this is intentionally conveyed this way as they do not expect to support any other address families]

* Are there no alignment requirements for the IP address in "Originating Routers IP Addr" inside the sub-TLV? I would think that alignment on a 4 byte boundary might be needed.

[Ballot comment]
I share Suhas' concerns.

Please expand the following acronyms upon first use and in the title;
see https://www.rfc-editor.org/materials/abbrev.expansion.txt for guidance.

- P2MP - Point-to-Multipoint
- PW - pseudowire
- LSP - Label Switched Path
- VPLS - Virtual Private LAN Service
- TE - Traffic Engineering (?)
- FEC - Forwarding Equivalence Class
- LSR - Label Switching Router
- GAL - Generic Associated Channel Label
- ACH - Associated Channel Header
- CE - ???
- PE - Provider Edge

[Ballot comment]
Please expand LSP and FEC on first mention. Please consider expanding PSN and LDP (I see they are marked as "well-known" in the abbreviation list, but I think expansion would be helpful in context.)

[Ballot comment]
I like the solution, but the document could do with some editing.

Major:
1: Sec 1.  Introduction
O:  Multi-segment Pseudowires support is out of scope of this document at  present and may be included in future.
P:  Multi-segment Pseudowires support is out of scope of this document.
C: Once published as an RFC, the document doesn't change. Could be "... may be addressed in a future document", but I'd suggest leaving it out.

2: General
The document has many unexpanded acronyms, e.g: ACH in "... MPLS label stack and IPv4 or IPv6 ACH."  In the Introduction you have: "such as P2MP ATM over PSN." - while PSN might count as a well known acronym, it feels like, in an Intro it should be less opaque - see https://www.rfc-editor.org/materials/abbrev.expansion.txt for RFC known acronyms.

3: The "Controlling Echo Responses" section feels weak -- it says that  "The procedures ... **can** be applied to P2MP PW LSP Ping." (emphasis added) - it feels like this should be a SHOULD? I think better a description of the DoS implications (other than just pointing at RFC6425) is also important.


Nits:
1: The document would benefit from some serious grammar checking -- e.g:
"... Echo Request to inform the receiver at P2MP MPLS LSP tail, of the P2MP PW being tested." - extra ','.
"For Inclusive P-Trees, P2MP MPLS LSP label itself can uniquely identify the Throughout the document..." - missing 'the' - things like this, and confusion over plurals (especially near acronyms) makes the document hard to read / review.

2: "P2MP ATM over PSN.  Requirements for ... " - extra space (nit!)

3: Sec 8.  Security Considerations
"The proposal introduced in this document does not introduce any new security considerations beyond that already apply to [RFC6425]." -- this sentence is poorly formed. Perhaps "beyond those that..."? Or "beyond those in"?

[Ballot comment]
  The LSP Ping Echo request IPv4/UDP packets is encapsulated with the
  MPLS label stack as described in previous sections, followed by one
  of the two encapsulation options:

IPv4 only?

And here Tianran Zhou's OPS DIR review:
No issue found. This document is well written, and is ready for publication.
Only a couple of nits, for the authors consideration:

1. in section 1, "Multipoint LDP (mDLP)"

Is the acronym "mLDP"?

2. in section 1,
"Multi-segment Pseudowires support is out of scope of this document at
  present and may be included in future."

At this stage, the I-D is stable. I think you can just say "Multi-segment Pseudowires support is out of scope of this document".

3. in section 6,
"MLDP" should align with the previous acronym in section 1, i.e. "mLDP".

And there is auto check result from the system:

  == Unused Reference: 'RFC5085' is defined on line 325, but no explicit
    reference was found in the text

  ** Obsolete normative reference: RFC 4379


    Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--).

    Run idnits with the --verbose option for more detailed information about
    the items above.

[Ballot comment]
Document: draft-ietf-pals-p2mp-pw-lsp-ping-03.txt

Assuming I am understanding this document correctly, it's just a refinement
of MPLS Echo to point out a specific receiver to respond. Is that correct?
If so, perhaps you could make that clear in the intro.

This document is pretty acronym heavy. Please ensure that every acronym
is expanded on first use. Examples include LSP, VPN, VPLS, etc.
Similarly, LSP Tail/Bud, etc. need citations.

Figure 2 would benefit from some explanations of the packet flow. Where
does the echo packet start, where does it stop? Who answers, etc.

[Ballot discuss]
Document: draft-ietf-pals-p2mp-pw-lsp-ping-03.txt

Assuming I am understanding this document correctly, it's just a refinement
of MPLS Echo to point out a specific receiver to respond. Is that correct?
If so, perhaps you could make that clear in the intro.

This document is pretty acronym heavy. Please ensure that every acronym
is expanded on first use. Examples include LSP, VPN, VPLS, etc.
Similarly, LSP Tail/Bud, etc. need citations.

Figure 2 would benefit from some explanations of the packet flow. Where
does the echo packet start, where does it stop? Who answers, etc.

[Ballot discuss]
I think the P2MP Pseudowire Sub-TLV in Section 4.1 is a bit under-specified. It is unclear how the address family of the originating router's IP address is communicated. Is this purely derived from the IP Addr Len (i.e. Len is 4 => IPv4, Len is 16 => IPv6)? If so, I think it would be useful to state this explicitly and add some validity checking and error handling for values other than 4 and 16.

[Ballot comment]
Are there no alignment requirements for the IP address in "Originating Routers IP Addr" inside the sub-TLV? I would think that alignment on a 4 byte boundary might be needed.

[Ballot comment]
I understand that this document does not introduce any new mechanisms compared to rfc6425, however, I think both documents enable an amplification attack. Is this not a concern or should that be discussed somewhere?

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

The IANA Services Operator has completed its review of draft-ietf-pals-p2mp-pw-lsp-ping-03.txt. If any part of this review is inaccurate, please let us know.

The IANA Services Operator understands that, upon approval of this document, there is a single action which we must complete.

In the Sub-TLVs for TLV Types 1, 16, and 21 subregistry of the TLVs registry on the Multiprotocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters registry page located at:

https://www.iana.org/assignments/mpls-lsp-ping-parameters/

a single, new sub-type is to be registered as follows:

Sub-Type: [ TBD-at-registration ]
Sub-TLV Name: P2MP Pseudowire
Reference: [ RFC-to-be ]

The IANA Services Operator understands that this is the only action required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed.

Thank you,

Sabrina Tanamal
IANA Services Specialist
PTI

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC: db3546@att.com, draft-ietf-pals-p2mp-pw-lsp-ping@ietf.org, agmalis@gmail.com, pals-chairs@ietf.org, Andrew Malis , pals@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Definition of P2MP PW TLV for LSP-Ping Mechanisms) to Proposed Standard


The IESG has received a request from the Pseudowire And LDP-enabled
Services WG (pals) to consider the following document:
- 'Definition of P2MP PW TLV for LSP-Ping Mechanisms'
  as Proposed Standard

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
ietf@ietf.org mailing lists by 2017-06-09. 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


  LSP-Ping is a widely deployed Operation, Administration, and
  Maintenance (OAM) mechanism in MPLS networks.  This document
  describes a mechanism to verify connectivity of Point-to-Multipoint
  (P2MP) Pseudowires (PW) using LSP Ping.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-pals-p2mp-pw-lsp-ping/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-pals-p2mp-pw-lsp-ping/ballot/


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

As required by RFC 4858, this is the current template for the Document Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(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?

Proposed Standard

(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:

  LSP Ping is a widely deployed Operations, Administration, and
  Maintenance (OAM) mechanism in MPLS networks. This document
  describes a mechanism to verify connectivity of Point-to-Multipoint
  (P2MP) Pseudowires (PW) using LSP Ping.

Working Group Summary:

There was nothing special in the WG process worth noting.

Document Quality:

This is a short draft that received several good reviews and comments along its path (see the acknowledgements section for the comment sources), and also a Routing Directorate review. It has not yet been implemented (to my knowledge), but there is at least one implementation planned.

Personnel:

Andy Malis is the Document Shepherd. Deborah Brungard is the Responsible Area Director.

(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.

This draft was reviewed and commented on by the document shepherd, which resulted in an update before IESG submission.

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

No.

(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.

(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.

None.

(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, IPR polls took place both at WG adoption and WG LC stages.

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

There are no IPR 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 were no objections at any stage to this draft.

(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.)

No.

(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.

Nits runs cleans with two minor comments, there is one unused reference (which is fine with me), and one RFC reference that needs to be updated by a recent replacement. This can be done by the RFC Editor.

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

N/A

(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?

No. draft-ietf-pals-p2mp-pw is currently in IESG review. All other normative references are 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.

No.

(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 5226).

This draft requests one IANA allocation, and no new registries.

(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, etc.

N/A