Label Switched Path (LSP) Ping/Traceroute for Segment Routing (SR) IGP-Prefix and IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data Planes
draft-ietf-mpls-spring-lsp-ping-13

[Ballot discuss]
Section 5.3 indicates that "Advertising Node Identifier" and "Receiving Node Identifier" are "4 or 6 octets." There are two issues that arise with the way this is currently specified, both of which can lead to a lack of interoperability:

1. While implementors might infer that "Protocol=1" results in a 4-byte value, and that "Protocol=2" results in a 6-byte value, it's a bit unclear what length is to be used here for "Protocol=0."

2. The descriptions for both of these fields include: "When Protocol is set to 1, then the 32 rightmost bits represent OSPF Router ID."  This implies that the field is *wider* than 32 bits when Protocol=1, which leaves deep ambiguity about the circumstances under which the field is allowed to be 4 octets.

I would strongly recommend that this section add clear language that unambiguously spells out how implementations are expected to select the field width for the four variable-width fields in this Sub-TLV (the two I cite above as well as the interface ID fields).

[Ballot comment]
Sections 5.1, 5.2, and 5.3 define "Reserved" fields without indication of how these fields should be treated. Recommend each of these be defined to "MUST be set to 0 on send, MUST be ignored on receipt" -- this is the scheme that maximizes the ability to use them in the future.

Section 5.3 sefines three values for "Adj Type": 0, 4, and 6. Please either state that all other values are and will always be an error, or create an IANA registry for this field.

Section 5.3 sefines three values for "Protocol": 0, 1, and 2. Please either state that all other values are and will always be an error, or create an IANA registry for this field.

[Ballot comment]
Authors have identified corrections:
- 5.1 requires reference to ietf-spring-segment-routing for definition
- 5.2 requires reference to ietf-spring-segment-routing for definition
- 5.3 need to remove reference to section 3.5 and only reference ietf-spring-segment-routing
(as section in document is being renumbered, best not to reference)
- change ietf-spring-segment-routing from normative reference to informative reference
for consistency with RFC8029 and other MPLS Ping documents which do as informative reference
to definitions (will consult with SPRING AD (Alvaro) before making change)

[Ballot comment]
(1) I’m surprised that there’s not even a passing reference to draft-ietf-spring-oam-usecase, given that it points to this draft in several places, among other things as “adding functionality to the use cases described by this document”.  I'm not advocating for a web of references, just surprised.

(2) The definition of a field with the name “Protocol” in Section 5. (Segment ID sub-TLV) got me a little confused when I went looking for a registry and found the values corresponding to the Downstream Detailed Mapping TLV (Section 6).  The name is ok, but I was wondering:  Can you reuse the existing registry for the values used on the Segment ID sub-TLV?  If so, then the values for OSPF/ISIS would change.  If not, then please have IANA set one up.

(3) What happens if there’s any error (invalid length, unknown protocol, etc.) in the sub-TLVs defined in Section 5?  I’m assuming that the action is specific to the TLV that contains them, or that there is something already specified in rfc8029 — please include a pointer, or specifics if needed.  I see that Section 7.4. (Segment ID Check) says that other values (for Protocol) “MUST be treated as Protocol value of 0” — that’s ok for now, but when/if other values are used this document would have to be Updated.  It may be better to say “any other unassigned value” (or maybe unrecognized, or something along those lines).

(4) I would really like to see a registry definition for Adj. Type (in 5.3).

[Ballot comment]
I can't emphasize strongly enough that my understanding of segment routing is neophyte-level on a good day, but I do have a question about Section 8.

I'm understanding that on a network path where some network elements support segment routing while others do not, what you can measure is a ping or traceroute to the first network element that doesn't support segment routing (or is it to the last network element that does support segment routing?), but you don't have any visibility along the path beyond that - do I have that right?

Assuming so ...

I didn't see anything about this topic before Section 8/page 16. Perhaps it's worth mentioning whether this works earlier in the document, perhaps in the Introduction?

My last point might not be in scope for this document, or even the SPRING working group, but if this is a limitation, any suggestions you could make to network operators with mixed networks (which I could imagine would be the rule, rather than the exception, as the technology is deployed) about what they can do to benefit most from this technology might be appreciated.

[Ballot comment]
I share Kathleen's concern. A related issue is the trust model: this allows one endpoint to potentially learn a lot about the MPLS topology. Is that an issue?

[Ballot comment]
I don't see mention of the possibility of the new LSP Ping and traceroute being used for reconnaissance. Is there a reason that i snot applicable or should it be added as a consideration?  Thanks.

Thanks for addressing the SecDir review:
https://mailarchive.ietf.org/arch/msg/secdir/HhRollkdh9Y581j7HlQys8kP4nE

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

The IANA Services Operator has completed its review of draft-ietf-mpls-spring-lsp-ping-09. If any part of this review is inaccurate, please let us know.

The IANA Services Operator has a question about one of the actions requested in the IANA Considerations section of this document.

The IANA Services Operator understands that, upon approval of this document, there are three actions which we must complete.

First, 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/

the following, three TEMPORARY registrations are to be made permanent and their references changed as follows:

Sub-Type Sub-TLV Name Reference
-------- ----------------- -------------------------
34 IPv4 IGP-Prefix Segment ID Section 5.1 [ RFC-to-be ]
35 IPv6 IGP-Prefix Segment ID Section 5.2 [ RFC-to-be ]
36 IGP-Adjacency Segment ID Section 5.3 [ RFC-to-be ]

Second, a new registry is to be created called the Protocol registry on the Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters registry page located at:

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

Code points in the range of 0-250 will be assigned by Standards Action as defined in RFC 8126. The range of 251-254 are reserved for experimental use and will not be assigned. There are initial registrations in the new registry as follows:

Value Meaning Reference
-------- ---------------- --------------------------
0 Unknown Section 3.4.1.2 of RFC8029
1 Static Section 3.4.1.2 of RFC8029
2 BGP Section 3.4.1.2 of RFC8029
3 LDP Section 3.4.1.2 of RFC8029
4 RSVP-TE Section 3.4.1.2 of RFC8029
5 OSPF Section 6 [ RFC-to-be ]
6 ISIS Section 6 [ RFC-to-be ]
7-250 Unassigned
251-254 Experimental use [ RFC-to-be ]
255 Reserved [ RFC-to-be ]

Third, in the Return Codes registry also on the Multi-Protocol 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 Return Code is to be registered as follows:

Value: [ TBD-at-registration ]
Meaning: Mapping for this FEC is not associated with the incoming interface
Reference: [ RFC-to-be ]

IANA Question --> What range should the new value be registered in?

The IANA Services Operator understands that these three actions are the only ones 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

The following Last Call announcement was sent out (ends 2017-10-06):

From: The IESG
To: IETF-Announce
CC: mpls@ietf.org, db3546@att.com, mpls-chairs@ietf.org, draft-ietf-mpls-spring-lsp-ping@ietf.org, Loa Andersson , loa@pi.nu
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Label Switched Path (LSP) Ping/Traceroute for Segment Routing IGP Prefix and Adjacency SIDs with MPLS Data-plane) to Proposed Standard


The IESG has received a request from the Multiprotocol Label Switching WG
(mpls) to consider the following document: - 'Label Switched Path (LSP)
Ping/Traceroute for Segment Routing IGP
  Prefix and Adjacency SIDs with MPLS Data-plane'
  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 2017-10-06. 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


  A Segment Routing architecture leverages source routing and tunneling
  paradigms and can be directly applied to use of a Multi Protocol
  Label Switching (MPLS) data plane.  A node steers a packet through a
  controlled set of instructions called segments, by prepending the
  packet with a Segment Routing header.

  The segment assignment and forwarding semantic nature of Segment
  Routing raises additional consideration for connectivity verification
  and fault isolation for an LSP within a Segment Routing architecture.
  This document illustrates the problem and defines extensions to
  perform LSP Ping and Traceroute for a Segment Routing network with a
  MPLS data plane.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-mpls-spring-lsp-ping/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-mpls-spring-lsp-ping/ballot/


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

  The MPLS working group request that

      Label Switched Path (LSP) Ping/Traceroute for
      Segment Routing Networks with MPLS Data-plane

            draft-ietf-mpls-spring-lsp-ping-06

  is published as an RFC on the Standards Track.

(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?

  This document specifies protocol and protocol information
  elements, it assigns IANA code points from registries and ranges
  there Standartds action is required. It also creates an IANA
  registry there Standards Action is the allocation policy for one
  of the ranges. Code points are allocated from this range.

(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

  When segement routing uses the MPLS data plane nature or segment
  assignment and forwarding semantic entails additional
  considerations for connectivity verification and fault isolation.
  This document illustrates the problem that arises when LSP are
  used with a Segment Routing architecture. The document also
  describe a mechanism to perform that allows normal  LSP Ping and
  Traceroute opeations to be performed over Segment Routing network
  running over an MPLS data plane.

Working Group Summary

  The working group is solidly behind this document.

Document Quality

  Are there existing implementations of the protocol? Have a
  significant number of vendors indicated their plan to
  implement the specification? Are there any reviewers that
  merit special mention as having done a thorough review,
  e.g., one that resulted in important changes or a
  conclusion that the document had no substantive issues? If
  there was a MIB Doctor, Media Type or other expert review,
  what was its course (briefly)? In the case of a Media Type
  review, on what date was the request posted?

  We know of at least two implementations.
  We have also started an implementation poll on the MPLS wg
  mailing list, as soon as further imformation is received we will
  update the write-up.

  No, Yang doctor, MIB doctor or other types of special reviews
  are necessary. The working group last call was announced on the
  SPRING wg mailing list.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

  Loa Andersson 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 document has quite a history, in itself it is a merger of two
  documents, but the understanding that we would have to do some
  work on LSP Ping for SPRING controlled networks has been there
  since the SPRING work started. The shepherd has been part of these
  discussions and also (as wg chair) promoted the merging of the
  two documents. The shepherd has reviewed the documents when they
  were first published as individual document, monitored the merging
  process and reviewed the merged document as part of the working
  group adoption poll. The shepherd also reviewed the document as
  part of the wglc.

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

  No such conserns.


(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 such reviews necessary.

(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 such concerns. This is a well reviewed document and there is
  working group consensus.

(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.

  The authors have all stated on the mailing list that they are
  unaware of any IPRs that are relevant for this document. We have
  requested input on IPRs on the MPLS working mailing list.

(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 against this document.

(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?

  The working group fully support this document. 

(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 such threats.

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

  The draft passes the nits tools with a comment on code, which
  seems not to be correct.

  There is also a "funny" reference, the first informative reference
  does have an odd format. One of the authors have opened a ticket
  on this since the error seems to be in the  the XML bibliography.

  Nuber of authors, there are 6 authors listed for this document.
  The document is a merger of of two early individual document, of
  which a least one resulted from discussins between two group with
  similar ideas.
  The merger resulted in a large number of co-authors, during the wg
  process this has been cut back to 6 -co-authors. After discussion
  with the authors the shepherd is convinced that the 6 listed
  authors have significantly contributed to the document, both
  participating in discussion and contbuting text. We would
  therefore like to have all the 6 co-authors listed on the front
  page.

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

  No formal reviews necessary.

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

  Yes, the references are correctly split into normative and
  informative.

(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 but two normative references are to existing RFCs, of the
  four, the two documents are spring wg drafts.

  draft-ietf-spring-segment-routing is in AD evaluation.
  draft-ietf-spring-segment-routing-mpls is in AD evaluation.

(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 downward refrences.

(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.

  Publication of this document will not change the status of any
  existing RFC.


(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).

  The shepherd has reviewed the IANA section, and also requested/
  suggested necessary changes. The document create a new IANA (sub-)
  registry, the allocation policies are clearly defined. The
  document include the intial contents for this registry.
  The name of the new registry will be "Protocol" registry and it
  will be placed under the "Multi-Protocol Label Switching (MPLS)
  Label Switched Paths (LSPs) Ping Parameters"

  Note to authors and chairs: Are we happy naming the new registry
  "Protocol"?

(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.

  The new registry does not require appointment of a experts.

(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.

  No such reviews necessary.

Request for posting confirmation emailed to previous authors: Nagendra Kumar , mpls-chairs@ietf.org, George Swallow , Carlos Pignataro , Sriganesh Kini , Hannes Gredler , Mach Chen , Nobo Akiya

Request for posting confirmation emailed to previous authors: Nagendra Kumar , George Swallow , Carlos Pignataro , Sriganesh Kini , Hannes Gredler , Mach Chen , Nobo Akiya

Request for posting confirmation emailed to previous authors: George Swallow , Nagendra Kumar , Hannes Gredler , mpls-chairs@ietf.org, Carlos Pignataro , Sriganesh Kini , Mach Chen , Nobo Akiya

Request for posting confirmation emailed to previous authors: George Swallow , Nagendra Kumar , Hannes Gredler , mpls-chairs@ietf.org, Carlos Pignataro , Sriganesh Kini , Mach Chen , Nobo Akiya

Request for posting confirmation emailed to previous authors: "Mach Chen" , "Nagendra Kumar" , "George Swallow" , mpls-chairs@ietf.org, "Carlos Pignataro" , "Nobo Akiya" , "Sriganesh Kini" , "Hannes Gredler"

Request for posting confirmation emailed to previous authors: "Mach Chen" , "Nagendra Kumar" , "George Swallow" , mpls-chairs@ietf.org, "Carlos Pignataro" , "Nobo Akiya" , "Sriganesh Kini" , "Hannes Gredler"