Covering Prefixes Outbound Route Filter for BGP-4
draft-ietf-bess-orf-covering-prefixes-06

[Ballot comment]
The Gen-ART review pointed out that the draft was difficult to read.

For what it is worth, I found the draft relatively hard to read and I knew much of the terminology already. But I was able to understand what the draft specified. But I think it would be useful make some additional edits along the lines of Adrian’s suggestions or perhaps beyond. One thing that I often find useful is to explain the semantics of a concept or field as early as possible. There were a few cases in this document where you talked about something for a while but it was only clear later what its meaning was. Example: there’s a lot of rules about the minlen field early in the draft, but it is only on page six that the spec actually says what it does. Explaining what it is for would have made understanding easier.

In any case, these are just comments from my perspective. This is a No-Obj position.

[Ballot comment]
I found myself wishing that the Abstract and/or Introduction included a sentence describing what a "covering prefix" was. "ORF" is nicely explained in the Introduction, but all I get on "covering prefix" is that they're applicable in Virtual Hub-and-Spoke VPNs and BGP/MPLS Ethernet VPN networks.

I actually know most of the terms defined in the Terminology section, but "covering prefix" isn't explained there, either.

The first clue I could find (searching for "cover") is on page 8, in this sentence.

  However, because Loc-RIB also
  contains a more specific covering route (3:192.0.2.0/89),
  2:192.0.2.0/88 does not match. 

I can guess what a covering prefix is using context clues, but I'm guessing.

[Ballot comment]
I found myself wishing that the Abstract and/or Introduction included a sentence describing what a "covering prefix" was. I actually know most of the terms defined in the Terminology section, and I can guess what a covering prefix is, but I'm guessing.

[Ballot comment]
I agree with Adrian's suggestions for this document.  Additionally, I would like to see the acronym RT expanded on first use. While making any other edits, please s/Contstrain/Constrain.

[Ballot comment]
Some minor editorial bits and pieces we can pickup after the telechat. (Thanks to Dave Black and Alvaro Retana for the reviews).

---

Something can be added to the Introduction (which is a bit short) to explain what a covering prefix is. Probably breaking the second paragraph after the first sentence and adding a new sentence that begins "A covering prefix is..."

---

The fields in Figures 1 are briefly described after the figure, but in some cases the description is exceeding brief. For example, minlen.

Can you look at the text and see where you can beef it up either with a forward reference to where the field is described, or with a simple statement about what the field is used for.

---

Final paragraph of Section 3

OLD>
  When the ROUTE-REFRESH message includes one or more CP-ORF entries,
  the BGP speaker MUST re-advertise routes that have been affected by
  ORF entries carried by the message.  While the speaker MAY also re-
  advertise the routes that have not been affected by the ORF entries
  carried in the message, this memo RECOMMENDS not to re-advertise the
  routes that have not been affected.

  When the ROUTE-REFRESH message includes one or more CP-ORF entries,
  the BGP speaker MUST re-advertise routes that have been affected by
  CP-ORF entries carried by the message.  While the speaker MAY also re-
  advertise the routes that have not been affected by the CP-ORF entries
  carried in the message, it is RECOMMENDED not to re-advertise the
  routes that have not been affected.

[Ballot comment]
Some minor editorial bits and pieces we can pickup after the telechat. (Thanks to Dave Black and Alvaro Retana for the reviews).

---

Something can be added to the Introduction (which is a bit short) to explain what a covering prefix is. Probably breaking the second paragraph after the first sentence and adding a new sentence that begins "A covering prefix is..."

---

The fields in Figures 1 are briefly described after the figure, but in some cases the description is exceeding brief. For example, minlen.

Can you look at the text and see where you can beef it up either with a forward reference to where the field is described, or with a simple statement about what the field is used for.

---

Section 3 has  "RECOMMENDS" which is not a 2119 word. To use "RECOMMENDED" you will need to reword slightly.

---

Section 8 has a paragraph that begins  "Section 5…” I think this applies specifically to the first bullet in the list (of two) immediately above. If I'm right, can you move the paragraph into that bullet?

---

Can you move RFC 4364 to be an Informative reference.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Covering Prefixes Outbound Route Filter for BGP-4) to Proposed Standard


The IESG has received a request from the BGP Enabled Services WG (bess)
to consider the following document:
- 'Covering Prefixes Outbound Route Filter for BGP-4'
  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 2015-02-18. 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 defines a new Outbound Route Filter (ORF) type, called
  the "Covering Prefixes ORF (CP-ORF)".  CP-ORF is applicable in
  Virtual Hub-and-Spoke VPNs.  It also is applicable in BGP/MPLS
  Ethernet VPN (EVPN) networks.


The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-bess-orf-covering-prefixes/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-bess-orf-covering-prefixes/ballot/


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

  http://datatracker.ietf.org/ipr/2397/
  http://datatracker.ietf.org/ipr/2398/

AD review
=====

Thanks for this document. I was hard-pushed to find anything to talk
about, so I guess you did a good job or I am losing my touch.

The points below are pretty minor, but they will get pulled up in
IETF last call reviews, so I think we should fix them in a new
revision before i start last call.

I'll put the document into "Revised I-D needed" state, and start the
last call as soon as I see a new revision.

Thanks for the work,
Adrian

---

In section 3

  When a BGP speaker receives a ROUTE-REFRESH message that contains a
  CP-ORF, and that ROUTE-REFRESH message violates any of the encoding
  rules specified in Section 2, the BGP speaker MUST log the event and
  ignore the entire ROUTE-REFRESH message.

I think you need to allow for event logging to implement thresholds to
avoid the logs becoming a gating factor when there is something evil
going on. Probably that makes

s/MUST/SHOULD/
And add "although an implementation MAY apply logging thresholds to
avoid excessive messaging or log file overflow."

---

Section 7 needs to include a request to the IANA to update the
references to the code points to point to this document when
published as an RFC.

---

Section 8 has

  o  When negotiating the ORF capability, advertise willingness to
      receive the CP-ORF only to known, trusted iBGP peers

which implies that there is a mechanism to
- negotiate the ORF capability
- advertise willingness to receive CP-ORF

Do you need a small section on this? Probably just a reference to the
negotiation process for the ORF capability, and a note saying how the
CP-ORF willingness is indicated.

---

I completely understand where you are coming from with section 8, but I
also know how our friends in the Security Area will respond.

Can you add a very short section noting...

  Security considerations for BGP are presented in [RFC4271] while
  further security analysis of BGP is found in [RFC6952].

(you'll have to add an informative reference to 6952)

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?

  The type of RFC which is requested is Proposed Standard.
  It defines information exchange between BGP peers, together with the
  format of the messages containing the information, as well as the
  processing rules. As such the type of RFC requested is appropriate.
  The type of RFC being requested appears 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

  A BGP speaker can send Outbound Route Filters (ORF) to a peer.  The
  peer uses ORFs to filter routing updates that it sends to the BGP
  speaker.  Using ORF, a BGP speaker can realize a "route pull"
  paradigm, in which the BGP speaker, on demand, pulls certain routes
  from the peer.
  This document defines a new ORF-type, called the "Covering Prefixes
  ORF (CP-ORF)".  CP-ORF is applicable in Virtual Hub-and-Spoke VPNs.
  It also is applicable BGP/MPLS Ethernet VPN (EVPN) networks.

Working Group Summary

  There has been no controversy relating to the technical aspect of
  this Document. A late IPR disclosure was made against this document
  (see question 8). The WG did not oppose to the progress of the
  document.

Document Quality

  The WG Chairs are aware of one implementation plan of the
  technologies described in this document. It should be noted that the
  contexts (Virtual Hub-and-Spoke VPNs and EVPNs) in which this
  Document applies are fairly recent thus explaining that
  implementations are not yet available
 
Personnel

  Martin Vigoureux is the Document Shepherd
  Adrian Farrel 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 did an extensive review of the document,
  checking for technology soundness, consistency with related
  documents and iana registries. The Document is ready.


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

  The Document was quite importantly discussed on the L3VPN mailing
  list since its first version. The most important changes/additions
  to the draft happened at that time. The document has been presented
  several times and discussed substantially at WG face to face meetings
  Although there was no reaction the the WG LC (support or opposition)
  the Document Shepherd has no concern about the depth/breadth of the
  reviews that have been performed.


(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 need.


(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 particular concern nor issues.


(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.

  IPR disclosures exist against this Document. IPR disclosures came
  after the decision to adopt the Document as a WG item. Authors of
  the Document are themselves authors of the disclosed IPR. The
  document has been downgraded back to an individual document and
  re-polled for adoption, and adopted.


(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?

  Consensus is solid. Several members of the WG participated to the
  discussion on this document and expressed their support at the time
  of adoption.


(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 extreme situation.


(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.

  I-Dnits is clean


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

  no need for that.


(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. at the time of this write-up only draft-ietf-l2vpn-evpn is not
  an RFC (but is currently in AUTH48 state).


(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 modify 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 IANA section is consistent with the body of the document. The Document
  makes use of two Code-Points from two different registries, the policy of which is
  FCFS. The cope-points were allocated at the time of a previous version of this
  Document (draft-ietf-l3vpn-orf-covering-prefixes-02).


(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.

  No new IANA registry is requested.


(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 pieces of text, thus no such review/test performed.