Interconnect Solution for Ethernet VPN (EVPN) Overlay Networks
draft-ietf-bess-dci-evpn-overlay-10

[Ballot comment]
I agree with Mirja's comment, and am curious about what aspects of this document
are believed to make it standards-track.

ID Nits reports:

  ** The abstract seems to contain references ([RFC7432]), which it
    shouldn't.  Please replace those with straight textual mentions of the
    documents in question.

[Ballot comment]
I have some nits to provide:
Section 1:
  BUM: it refers to the Broadcast, Unknown unicast and Multicast
I suggest dropping "it" (so,  "BUM: refers to the Broadcast, Unknown unicast and Multicast")

Section 2:
"While this model provides a scalable and efficient multi-tenant  solution within the Data Center, it might not be easily extended to the Wide Area Network (WAN) in some cases due to the requirements and existing deployed technologies. "
I must admit that I don't quite understand the point of "in some cases due to the requirements" - what is this trying to say? Is it needed? If so, is the "in some cases" bit needed (the "it might not be" feels like weasel words already).

Nit: "This document describes a Interconnect " -> "This document describes an Interconnect "

Question: "This document describes a Interconnect solution for EVPN overlay networks, assuming that the NVO Gateway (GW) and the WAN Edge functions can be decoupled in two separate systems or integrated into the same system."
I suspect that I'm missing something, but I don't quite understand the "assuming that" bit. You are saying that they can either be separate or combined, is there a 3rd option? Or is the "assuming" redundant?

Questions: You say "Per-flow load balancing is not a strong requirement since a deterministic path per service is usually required..." -- doesn't this make it not just not a strong requirement, but rather a non-goal, or something to be avoided? ("Not a strong requirement" sounds like it would be a nice-to-have, but that conflicts with "deterministic path").

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

The IANA Services Operator has reviewed draft-ietf-bess-dci-evpn-overlay-06, 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 2018-02-09):

From: The IESG
To: IETF-Announce
CC: martin.vigoureux@nokia.com, draft-ietf-bess-dci-evpn-overlay@ietf.org, bess-chairs@ietf.org, bess@ietf.org, aretana.ietf@gmail.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Interconnect Solution for EVPN Overlay networks) to Proposed Standard


The IESG has received a request from the BGP Enabled ServiceS WG (bess) to
consider the following document: - 'Interconnect Solution for EVPN Overlay
networks'
  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 2018-02-09. 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


  This document describes how Network Virtualization Overlays (NVO) can
  be connected to a Wide Area Network (WAN) in order to extend the
  layer-2 connectivity required for some tenants. The solution analyzes
  the interaction between NVO networks running Ethernet Virtual Private
  Networks (EVPN) and other L2VPN technologies used in the WAN, such as
  Virtual Private LAN Services (VPLS), VPLS extensions for Provider
  Backbone Bridging (PBB-VPLS), EVPN or PBB-EVPN. It also describes how
  the existing Technical Specifications apply to the Interconnection
  and extends the EVPN procedures needed in some cases. In particular,
  this document describes how EVPN routes are processed on Gateways
  (GWs) that interconnect EVPN-Overlay and EVPN-MPLS networks, as well
  as the Interconnect Ethernet Segment (I-ES) to provide multi-homing,
  and the use of the Unknown MAC route to avoid MAC scale issues on
  Data Center Network Virtualization Edge (NVE) devices.





The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-bess-dci-evpn-overlay/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-bess-dci-evpn-overlay/ballot/

The following IPR Declarations may be related to this I-D:

  https://datatracker.ietf.org/ipr/2586/
  https://datatracker.ietf.org/ipr/2951/



The document contains these normative downward references.
See RFC 3967 for additional information:
    rfc7041: Extensions to the Virtual Private LAN Service (VPLS) Provider Edge (PE) Model for Provider Backbone Bridging (Informational - IETF stream)

=== AD Review of draft-ietf-bess-dci-evpn-overlay-05 ===
https://mailarchive.ietf.org/arch/msg/bess/rpSun0o4TPdELPaH-rwBBmHKWJg/?qid=0d6b835ab5ffc06fe92f964807e5d533

Dear authors:

I just finished reading this document.

As with draft-ietf-bess-evpn-overlay, it seems to me that this document is
better suited as an Applicability Statement [1] instead of a Technical
Specification -- both would result in a Standards Track document.  It is
hard for me to clearly identify what this document is specifying, vs
explaining how to use existing mechanisms (already specified elsewhere) to
achieve the DCI.  I don't want to dig too deep into this point, but it
would be nice if you at least considered refocusing the text.

I do have some more comments below.  I'll wait for an updated draft before
starting the IETF Last Call.

Thanks!

Alvaro.

[1] https://tools.ietf.org/html/rfc2026#section-3.2


Major:

M1. I don't feel too good about using Normative Language to describe the
requirements (2.1 and 3.1) because the normative part of this document
should be the solution itself, not the requirements (which the solution
will then solve).  As I read the requirements, with the Normative Language
in them, there are questions that come up, which wouldn't be there if
rfc2119 keywords were not used.

M1.1. There's an important use of the words "supported" and "implemented",
what do they mean from a Normative point of view?  Are you using them from
the point of view of the operator implementing something in their network,
or the solution (the software feature) including them?  How do you
Normatively enforce that?  Some examples of their use are: "Per-service
load balancing MUST be supported. Per-flow load balancing MAY be
supported..." (2.1), "The following optimizations MAY be supported..."
(2.1), "Multi-homing MUST be supported. Single-active multi-homing with
per-service load balancing MUST be implemented. All-active multi-homing,
i.e. per-flow load-balancing, SHOULD be implemented as long as the
technology deployed in the WAN supports it" (3.1).  In summary, I think
that the requirements would be better served with non-rfc2119 language.

M1.2. The use of "MUST be supported" doesn't stop when talking about the
requirements:

M1.2.1. In 2.4: "As already discussed, single-active multi-homing, i.e.
per-service load-balancing multi-homing MUST be supported in this type of
interconnect."  Assuming you take off the Normative Language in 2.1, take
out "as already discussed"...

M1.2.2. In 2.5: "The following features MAY be supported..."  I'm assuming
"MAY" is used here because the optimizations are optional; saying so would
be better as some of the descriptions in the sub-sections include other
Normative Language.

M1.2.2. In 2.3 an option exists...but in both cases "MUST be supported" is
used.  As I asked above, what does this mean from the enforcement of the
Normative Language point of view? If we think about interoperability, then
maybe a more prescriptive sentence would work better.  Suggestion: s/the
provisioning of the VCID for such PW MUST be supported on the MAC-VRF/the
VCID MUST be provisioned...

M1.2.3. In 3.2.2./3.3.2: "Single-active multi-homing MUST be supported on
the GWs." ...

M1.2.4. 3.4.3/3.5.2: "Single-active as well as all-active multi-homing MUST
be supported."


M2. From 2.5.3: "Individual AC/PW failures MAY be detected by OAM
mechanisms."  The "MAY" seems to just be stating a fact; s/MAY/may

M2.1. The two "MAYs" in the bullets following the "for instance" seem out
of place too.  If the intent is to just list two possibilities (examples)
then the "MAYs" should not be Normative.


M3. Security Considerations.  Please see my note above about thinking that
this document is more appropriate to be an Applicability Statement (than a
Technical Specification).  The Security Considerations section basically
directs the reader to existing work.  I would like to see a statement (for
the benefit of the security reviewers) along the lines of: "This document
defines...as a result there are no new security considerations."  Note that
considering this document a Technical Specification by definition it means
it adds something -- so please focus on that here.


M4. References: The reference to draft-ietf-bess-evpn-overlay should be
Normative.


Minor:

P1. The "Conventions and Terminology" (Section 5) should be moved to the
front of the document.

P2. Please add references to VPLS, EVPN, VXLAN, 802.1q/ag, etc, etc. on
first mention.  All these technologies are important in understanding the
document, but only some are properly referenced later.  Ideally, there
would be a reference when a mayor technology is mentioned (specially the
first time) and when other important features are mentioned and assumed --
for example: in "Even if optimized BGP techniques like RT-constraint are
used..." it would be nice to put a reference to RT-constraint.  It's all
about the completeness of the document...

P2.1. In 2.3: "the usual MPLS procedures between GW and WAN Edge router"; a
reference here would be nice.

P3. Please use the template in rfc8174, instead of the one in rfc2119.

P4. In 3.4.1, I can't really parse this text: "Normally each GW will setup
one (two) BGP EVPN session(s) to the DC RR(s) and one(two) session(s) to
the WAN RR(s)."  Specifically the "one (two)" part.

P5. The IANA Considerations section is empty [
https://tools.ietf.org/html/rfc8126#section-9.1].


Nits:

N1. I know that many of the abbreviations are well-known by now, but please
expand as needed, specially in the first few sections to give the readers a
better idea of the content.  Note that PBB and VPLS are in the "RFC Editor
Abbreviations List" [2], but, surprisingly EVPN is not.  [Note to
self/shepherd: ask the RFC Editor to add EVPN when this document gets to
them.]

N1.1. Figure 2 includes "EVPN-Ovl", which is not expanded or explained
anywhere.  I'm guessing this is just a general EVPN-Overlay, but the reader
shouldn't have to guess.

N2. Section 4 doesn't exist.

N3. 3.4.1: "Optionally, different I-ESI values MAY be configured..."
"Optionally...MAY" is redundant.

[2] https://www.rfc-editor.org/materials/abbrev.expansion.txt

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 RFC is requested. It is indicated in the header.
It matches with the content of the Document which defines protocol procedures.

(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 describes how Network Virtualization Overlay networks
  (NVO) can be connected to a Wide Area Network (WAN) in order to
  extend the layer-2 connectivity required for some tenants. The
  solution analyzes the interaction between NVO networks running EVPN
  and other L2VPN technologies used in the WAN, such as VPLS/PBB-VPLS
  or EVPN/PBB-EVPN, and proposes a solution for the interworking
  between both.

Working Group Summary

  The BESS WG supports the publication of this Document as a Proposed Standard RFC

Document Quality

  Several implementations of this technology exist.
  The Document is clear and well written.

Personnel

  Martin Vigoureux is the Document Shepherd
  Alvaro Retana is the Responsible AD

(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.

  The Document Shepherd has done a complete and general review of the Document.
  A new version has been published as a result. This Document is ready to be submitted to IESG.

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

  No concern.

(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 portion of the Document requires a review from a particular or broader perspective.

(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 concern.

(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.

  All Authors and Contributors have made a statement regarding their knowledge of IPR which would relate to this Document.

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

  Two IPR disclosures have been made against this Document.
  The WG did not raise any issue with the existence of these IPR.

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
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  The consensus is solid.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
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  No.

(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.

  ID nits should be clear.

(12) Describe how the document meets any required formal review
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  No formal review required.

(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 such reference.

(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 Normative reference.

(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
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  The publication of this Document will not change the status of any RFC.

(17) Describe the Document Shepherd's review of the IANA considerations
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document. Confirm that all protocol extensions that the document makes
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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 Document makes to request to IANA.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
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  No registry required.

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  No section of the Document are written in a formal language which require automatic checks.

Request for posting confirmation emailed to previous authors: Senthil Sathappan , Senad Palislamovic , Jorge Rabadan , Wim Henderickx , Dennis Cai , bess-chairs@ietf.org, Ali Sajassi