Requirements for Scalable DNS-Based Service Discovery (DNS-SD) / Multicast DNS (mDNS) Extensions
draft-ietf-dnssd-requirements-06

[Ballot comment]
Section 5:

  SSD should support rich internationalized labels within Service
  Instance Names, as DNS-SD/mDNS does today.  SSD must not negatively
  impact the global DNS namespace or infrastructure.

A reference to soon-to-be-RFC-draft-ietf-precis-framework would be nice here.

[Ballot discuss]
[Updating to reflect that the IPR disclosure issue is addressed. There is an IPR disclosure that appears for this document, but it was a mistakenly filed disclosure that still remains in the system. We will deal with that issue separately.]

Section 5:

OLD
  Devices on different links may have the same mDNS name (perhaps due
  to vendor defaults), because link-local mDNS names are only
  guaranteed to be unique on a per-link basis.  Also, even devices that
  are on the same link may have similar-looking names, such as one
  device with the name "Bill" and another device using the similar-
  looking name "Bi11" (using the digit "1" in place of the letter "l").
  This may lead to a local label disambiguation problem between
  presented results.
 
  SSD should support rich internationalized labels within Service
  Instance Names, as DNS-SD/mDNS does today.  SSD must not negatively
  impact the global DNS namespace or infrastructure.

The part about name collisions is fine, and should be said. The part about disambiguating similar characters is a rat's nest I really think you need to avoid. We can discuss this further, but the i18n community is dealing with this issue right now and it's a mess you really don't want to get into. I think you should simply stick to something like this:

NEW
  Devices on different links may have the same mDNS name (perhaps due
  to vendor defaults), because link-local mDNS names are only
  guaranteed to be unique on a per-link basis. SSD needs to deal with
  name collisions beyond local link considerations.
 
  SSD should support rich internationalized labels within Service
  Instance Names, as DNS-SD/mDNS does today and should look to work in
  using internationalize strings in application protocols
  [soon-to-be-RFC-draft-ietf-precis-framework].  SSD must not
  negatively impact the global DNS namespace or infrastructure.

[Ballot comment]
  Wireless networks such as Wi-Fi [IEEE.802.11] may be adversely
  affected by excessive mDNS traffic due to the higher network overhead
  of multicast transmissions.

It's excessive becasue they are adversely affected not the other way around.

[Ballot comment]
The IETF should definitively focus on this problem space. Thanks.

Some comments below:

- I agree with Martin's comment.

- Section 4, REQ8 looks a very fundemental requirement for all service discovery mechanism. It does not look like a specific requirement for SSD

- Some of the requirements will be hard to fulfill, if taken literally:
  REQ9:  SSD should operate efficiently on common link layers and link
          types.

  REQ12:  SSD should enable a way to provide a consistent user
          experience whether local or remote services are being
          discovered.

- Very surprised that the Security Considerations don't lead to formal requirements
For example, in connection with "6.1 Scope of Discovery" and "6.5 Access Control", I was expecting a requirement such as
  REQXX:  the owner of the advertised service must be able to configure whether his service should be advertised beyond the local link

The way the requirements are specified: all services will be visible to everybody, and the access control will accept/reject the service request. That reminds me of the typical airport wireless situation: you try every wireless network to see which one will accept you.

[Ballot comment]
- I agree with Martin's comment.

- Section 4, REQ8 looks a very fundemental requirement for all service discovery mechanism. It does not look like a specific requirement for SSD

- Some of the requirements will be hard to fulfill, if taken literally:
  REQ9:  SSD should operate efficiently on common link layers and link
          types.

  REQ12:  SSD should enable a way to provide a consistent user
          experience whether local or remote services are being
          discovered.

- Very surprised that the Security Considerations don't lead to formal requirements
For example, in connection with "6.1 Scope of Discovery" and "6.5 Access Control", I was expecting a requirement such as
  REQXX:  the owner of the advertised service must be able to configure whether his service should be advertised beyond the local link

The way the requirements are specified: all services will be visible to everybody, and the access control will accept/reject the service request. That reminds me of the typical airport wireless situation: you try every wireless network to see which one will accept you.

[Ballot discuss]
Procedural issue - The shepherd writeup says:

  (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 draft includes the boilerplate confirming that the document "is
  submitted in full conformance with the provisions of BCP 78 and BCP
  79". No disclosures have been made, nor are expected to be made in an
  Informational requirements draft.

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

  No.

There was an IPR disclosure made on the earlier pre-WG version of this document back in 2013. Were the authors asked whether that disclosure also applies to this version of the document? Is the WG aware of this disclosure? Did the WG discuss the disclosure? Were any concerns raised?

Section 5:

OLD
  Devices on different links may have the same mDNS name (perhaps due
  to vendor defaults), because link-local mDNS names are only
  guaranteed to be unique on a per-link basis.  Also, even devices that
  are on the same link may have similar-looking names, such as one
  device with the name "Bill" and another device using the similar-
  looking name "Bi11" (using the digit "1" in place of the letter "l").
  This may lead to a local label disambiguation problem between
  presented results.
 
  SSD should support rich internationalized labels within Service
  Instance Names, as DNS-SD/mDNS does today.  SSD must not negatively
  impact the global DNS namespace or infrastructure.

The part about name collisions is fine, and should be said. The part about disambiguating similar characters is a rat's nest I really think you need to avoid. We can discuss this further, but the i18n community is dealing with this issue right now and it's a mess you really don't want to get into. I think you should simply stick to something like this:

NEW
  Devices on different links may have the same mDNS name (perhaps due
  to vendor defaults), because link-local mDNS names are only
  guaranteed to be unique on a per-link basis. SSD needs to deal with
  name collisions beyond local link considerations.
 
  SSD should support rich internationalized labels within Service
  Instance Names, as DNS-SD/mDNS does today and should look to work in
  using internationalize strings in application protocols
  [soon-to-be-RFC-draft-ietf-precis-framework].  SSD must not
  negatively impact the global DNS namespace or infrastructure.

[Ballot comment]
I'm glad to see this moving forward. I have a few minor comments, but just do the right thing.

I was at at least one BOF where this was discussed, so I kind of knew what to expect, but I didn't find the title clear. Could the word "multi-link" be added someplace?

This text:

      It is common practice for enterprises and
      institutions to use wireless links for client access and wired
      networks for server infrastructure, typically on different
      subnets.
     
didn't seem quite right. Is it saying

      It is common practice for enterprises and
      institutions to use wireless links for client access to wired
                                                          ^^
      networks for server infrastructure, typically on different
      subnets. 
     
? As written, this excludes my office network, which includes both clients on wired and wireless links, and I suppose that's an environment where this extension might be useful ...

(an embarrassingly small nit) In this text:

  SSD should support rich internationalized labels within Service
  Instance Names, as DNS-SD/mDNS does today.  SSD must not negatively
  impact the global DNS namespace or infrastructure.
 
the two requirements don't seem particularly related, and I wonder if the second would get more attention if it was a separate paragraph.

[Ballot comment]

- section 6 intro: I'm not sure I buy that the set of relevant
threats is only a union as stated. There are often new threats
in new environments.

- 6.6: I think one can also leak private information by
searching in too broad a scope, e.g. if the client can be
fingerprinted allowing re-identification. I think that's
different from the example given, and maybe worth noting too.

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-dnssd-requirements-04, which is currently in Last Call, and has the following comments:

We understand that, upon approval of this document, there are no IANA Actions that need completion.

While it is helpful for the IANA Considerations section of the document to remain in place upon publication, if the authors prefer to remove it, IANA doesn't object.

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

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Correction: Last Call:  (Requirements for Scalable DNS-SD/mDNS Extensions) to Informational RFC


The IESG has received a request from the Extensions for Scalable DNS
Service Discovery  WG (dnssd) to consider the following document:
- 'Requirements for Scalable DNS-SD/mDNS Extensions'
  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
ietf@ietf.org mailing lists by 2015-01-07. 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


  DNS-SD/mDNS is widely used today for discovery and resolution of
  services and names on a local link, but there are use cases to extend
  DNS-SD/mDNS to enable service discovery beyond the local link.  This
  document provides a problem statement and a list of requirements.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-dnssd-requirements/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-dnssd-requirements/ballot/


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

  http://datatracker.ietf.org/ipr/2114/

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Requirements for Scalable DNS-SD/mDNS Extensions) to Informational RFC


The IESG has received a request from the Extensions for Scalable DNS
Service Discovery  WG (dnssd) to consider the following document:
- 'Requirements for Scalable DNS-SD/mDNS Extensions'
  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
ietf@ietf.org mailing lists by 2014-01-07. 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


  DNS-SD/mDNS is widely used today for discovery and resolution of
  services and names on a local link, but there are use cases to extend
  DNS-SD/mDNS to enable service discovery beyond the local link.  This
  document provides a problem statement and a list of requirements.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-dnssd-requirements/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-dnssd-requirements/ballot/


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

  http://datatracker.ietf.org/ipr/2114/

(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.

(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:

DNS-SD/mDNS is widely used today for discovery and resolution of services and names on a local link, but there are use cases to extend DNS-SD/mDNS to enable service discovery beyond the local link.  This document provides a problem statement and documents a set of requirements against which solutions can be designed and measured.

Working Group Summary:

The WG generally reached strong consensus on all points, including all requirements, in the document.

There was some specific discussion about whether wireless links should be treated differently, but it was agreed that REQ9 should be generalised and say "SSD should operate efficiently on common link layers and link types."

The evolution of the other requirements was quite smooth with good consensus.

Document Quality:

As a requirements document, a number of implementors/vendors have expressed an interest in working towards a common, interoperable solution for service discovery across multiple links.

No specialist review was required.

A separate threat analysis is being documented through draft-rafiee-dnssd-mdns-threatmodel-01.

Personnel:

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

Document shepherd: Tim Chown

Responsible AD: Ted Lemon

(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 shepherd has reviewed the draft through its iterations in the dnssd WG and believes it represents full and fair consensus of the WG. The document was in reasonable shape by IETF89, and a small number of final points were agreed at IETF90. The shepherd ensured that the authors applied the updates agreed by the WG.

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

The document has been reviewed and commented on by a number of experienced WG members, and thus I am happy with the quality of review of the document.

(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. Though a threat analysis activity for dnssd has been spun out into a separate dcoument, draft-rafiee-dnssd-mdns-threatmodel-01, which is being presented and discussed at IETF91. I believe the main requirements text can advance as is meanwhile.

(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.

The requirements document has allowed consensus to be agreed within the dnssd WG on the properties required of potential solution(s) and solution elements.

The WG showed a strong consensus to advance the document.

(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 draft includes the boilerplate confirming that the document "is submitted in full conformance with the provisions of BCP 78 and BCP 79". No disclosures have been made, nor are expected to be made in an Informational requirements draft.

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

No.

(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 a strong consensus on the document, and progressing it.

The only person expressing anything like strong views against parts of the document is Doug Otis, who has expressed comments about trill, and use of ULA overlays. The chairs do not believe his comments are relevant to the WG.

(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.

None.

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

None applicable.

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

Yes.

Some references need updating, but this can be handled by the RFC Editor, paricularly homenet-arch, now RFC7368, and making the format of the mDNS and DNS-SD references consistent.

(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.

(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).

N/A

(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.

N/A

(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.

None.