Analysis of IPv6 Link Models for 802.16 Based Networks
draft-ietf-16ng-ipv6-link-model-analysis-03

[Ballot discuss]
What is going to be role of RSN (routing over wireless networks). Are routing considerations going to be here or there. If in this WG, then routing issues need to be detailed.

[Ballot discuss]
What is going to be role of RSN (routing over wireless networks). Are routing considerations going to be here or there. If in this WG, then routing issues need to be detailed.

[Ballot discuss]
The Security Considerations proposed as an Editor's Note are an imporvement, but the reference to 802.16e  should be supplemented by model specific references.  I understand that security considerations for the different link models are not introduced by this document, but I believe that - at a minimum - references to the specifications where these security considerations are documented is needed.  It is too hard for the reader to find this information.  Security Considerations for the Ethernet Like Link Model are adequately addressed in RFCs 2461 and 2462 (normative references [1] and [2]).  The point-to-point link model is defined in RFC 3314 but says only "[This specification] does not specify a protocol, and it introduces no new security considerations."  The Shared IPv6 Prefix Link Model does not have a well-defined reference, so I assume the security considerations are not well documented.  If the security considerations for point-to-point and shared prefix models are not specified elsewhere, I believe they should be added to this document.

[Ballot discuss]
The Security Considerations proposed as an Editor's Note are an imporvement, but the reference to 802.16e  should be supplemented by model specific references.  I understand that security considerations for the different link models are not introduced by this document, but I believe that - at a minimum - references to the specifications where these security considerations are documented is needed.  It is too hard for the reader to find this information.  Security Considerations for the Ethernet Like Link Model are adequately addressed in RFCs 2461 and 2462 (normative references [1] and [2]).  The point-to-point link model is defined in RFC 3314 but says only "[This specification] does not specify a protocol, and it introduces no new security considerations."  The Shared IPv6 Prefix Link Model does not have a well-defined reference, so I assume the security considerations are not well documented.  If the security considerations for point-to-poeint and shared prefix models are not specified elsewhere, I believe they should be added to this document.

[Ballot discuss]
It seems clear that the model used for modelling 802.16 subnets could
have a significant implication on the operation of routing protocols. This would be most obviously true if OSPF or IS-IS tried to operate over
one of these subnets. The extent to which this model will have an impact
on routing protocols depends upon where in the overall network the
802.16 subnet resides, with the least impact on routing occurring in the
place that these networks are actually expected to occur: On the edge,
where connectivity is intentionally limited.

Fully resolving how it might fit into other parts of the network seems
like a larger task that it would be reasonable to require the authors to
take on, and may be the role of a different working group. Therefore, I
propose that we add a note that warns that the choice of model may have
an impact on routing, but that this impact is outside of the scope of
this document. For example, the note might be along the lines of:

    The model used for modelling 802.16 networks may have a
    significant impact on Internet routing. However, the specific
    routing aspects of this model are outside of the scope of this
    document.

Optionally you might consider appending one more sentence to this
paragraph along the lines of:

  The impact on routing is likely to be the most straightforward
  on the provider edge if connectivity is intentionally limited to
  point to point connectivity from one PE to any one of multiple CEs,
  and also to pre-configured multicast from the PE to multiple CEs.

[Ballot comment]
Nits:
Section 3.1 para 1:
  for constructing their global IPv6 addresses, however this model does
  not any multicast capability.  The following figures illustrates high
      ^                                                ^^^^^^^^^^^
  provide?                                            illustrate a
  level view of this link model wherein one more prefixes advertised on
                                            ^
                                            or

[Ballot comment]
3.2.3.1.  Reuse of existing standards

  This solution reuses RFC 2461, 2462, and if PPP is used, RFC 2472 and
  RFC 2516.  No changes in these protocols are required, the protocols
  must only be configured properly.

Some of these RFCs are not "Standards" - RFC2516 is an an Informational RFC Editor's submission, for example.

[Ballot comment]
Gen-ART Review by Gonzalo Camarillo.

  Acronyms (e.g., MS, BS, and MLD) should be expanded on their first use.

  The draft talks about WiMAX defining the WiMAX transport connection but
  does not provide a reference.

[Ballot comment]
INTRODUCTION, paragraph 2:
>          Analysis of IPv6 Link Models for 802.16 based Networks

  Add "IEEE" in front of 802.16 and other IEEE spec numbers throughout
  the document.


Section 6., paragraph 0:
>    3.  IPv6 Link Models for 802.16 based Networks . . . . . . . . . .  4
>      3.1.  Shared IPv6 Prefix Link Model  . . . . . . . . . . . . . .  4
>        3.1.1.  Prefix Assignment  . . . . . . . . . . . . . . . . . .  5
>        3.1.2.  Address Autoconfiguration  . . . . . . . . . . . . . .  5
>        3.1.3.  Duplicate Address Detection  . . . . . . . . . . . . .  5
>        3.1.4.  Considerations . . . . . . . . . . . . . . . . . . . .  6
>        3.1.5.  Applicability  . . . . . . . . . . . . . . . . . . . .  7
...
>    4.  Renumbering  . . . . . . . . . . . . . . . . . . . . . . . . . 12
>    5.  Effect on Dormant Mode . . . . . . . . . . . . . . . . . . . . 13

  It's confusing to see some characteristics being discussed in
  subsections (e.g., Prefix Assignment) and others in standalone
  sections (e.g., Renumbering). Also, a discussion of DAD for the
  point-to-point model seems to be missing?


  Expand acronyms on first use (MS, BS, CS, etc.)


Section 802.16, paragraph 2:
>    And finally this document provides a
>    recommendation for choosing one link model that best suits for the
>    deployment.

  Section 6 doesn't state _a_ recommendation. It basically says that all
  three models are useful in some deployments. Not sure how useful
  this is.

[Ballot comment]
I understand that security considerations for the different link models are not introduced by this document, but I would suggest that a reference to the rfcs where these security considerations are documented is appropriate.  If the security considerations are not specified elsewhere, I would suggest adding them to this document.

Ad review posted:

I have reviewed this document again.
Please see a few comments below:

> 3.1.  Shared IPv6 Prefix Link Model
This section should start with a definition of
the model.

> 3.1.4.5.  Changes to Host Implementation
>
>    This link model requires no other implementation changes except that
>    the hosts are required to perform duplicate address detection for all
>    addresses even if the host is reusing the interface identifier.
Is this a remnant from an earlier revision? If you employ
MLD snooping as opposed to looking at NAs, it would
appear that the above is not true.
>    802.16 [1] [2] is a connection oriented access technology for the
>    last mile without bi-directional native multicast support. 802.16 has
>    only downlink multicast support and there is no mechanisms defined
>    for mobile stations to be able to send multicast packets that can be
>    mapped to downlink multicast connection.  This could be a problem for
>    IP protocols (e.g.  ARP, IPv6 ND) that traditionally assume the
>    availability of multicast at the link layer.
This statement may need to be revised according to DJ's
recent comments on the list.
>    3.  If neither PPP nor VLAN is used, the set of 802.16 connections
>        can be viewed as a virtual point-to-point link for the purpose of
>        neighbor discovery and address configuration.  For IPv6 CS, this
>        may be used to implement the point-to-point link.
The key issue is not what you do with ND, but rather
what the scope of the link local multicast is; that
determines what happens to RAs, NAs, etc.

>    When the p2p link model is used, the BS acts as a bridge.  For each
>    MS, the BS bridges the unique prefix or set of prefixes assigned by
>    the AR to the link between itself and the MS.  This means, in
>    particular, that the per MS prefix or set of prefixes are routed on
>    both sides (wireless and wired) of the BS, and that the BS needs to
>    participate in all 802 standard bridging protocols.
The expression "routed on both sides" may not be
appropriate here. The BS is not a router.

Question: why is it that the BS needs to participate in
all bridging protocols? From the perspective of the
MS it shouldn't even see the existence of a tunnel
behind the BS.

>    One way to construct an Ethernet like link is to implement bridging
>    [13] between BSs and AR like switched Ethernet.  In the Figure 4,
>    bridging performs link aggregation between BSs and AR.  Bridging also
>    supports multicast packet filtering.  Another way to implement this
>    model is by using VLAN function [11].

I do not understand how VLANs relate to this. Please explain or
remove.

>    In this model, an IPv6 prefix is shared by multiple MSs on top of
>    IEEE 802.16 point-to-multipoint links.  Also this model supports
>    multiple access routers and multiple hosts behind an MS as shown in
>    Figure 4.

Yes, but a question: should this be taken as a claim that the
other models do not support multiple hosts? The document
does not say anything about this.
>    conjunction with IP convergence sublyaer with IPv6 classifiers.
Typo.

PROTO Write-up

(1.a) Who is the Document Shepherd for this document? Has the
Document Shepherd personally reviewed this version of the
document and, in particular, does he or she believe this
version is ready for forwarding to the IESG for publication?

Daniel Park is the Document Shepherd for this document. I've reviewed
this document and it is ready for advancing to the IESG for publication.

(1.b) Has the document had adequate review both from key WG members
and from key non-WG members? Does the Document Shepherd have
any concerns about the depth or breadth of the reviews that
have been performed?

Many 802.16 and IPv6 experts reviewed this document. This document
is result of a Design Team including the 16ng WG technical advisors,
IEEE 802.16 liaison as well as WiMAX key members that was formed to
analysis the IPv6 link models for 802.16 networks. This document went
through the 2 weeks WGLC in the 16ng WG. I have no concern about
the depth or breadth of the reviews that have been performed.

(1.c) Does the Document Shepherd have concerns that the document
needs more review from a particular or broader perspective,
e.g., security, operational complexity, someone familiar with
AAA, internationalization or XML?

None.

(1.d) Does the Document Shepherd have any specific concerns or
issues 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.

(1.e) 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 strong WG consensus in advancing this document.

(1.f) 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
entered into the ID Tracker.)

No.

(1.g) Has the Document Shepherd personally verified that the
document satisfies all ID nits? (See
http://www.ietf.org/ID-Checklist.html and
http://tools.ietf.org/tools/idnits/). Boilerplate checks are
not enough; this check needs to be thorough. Has the document
met all formal review criteria it needs to, such as the MIB
Doctor, media type and URI type reviews?

No nits found. There is a minor nit in RFC 3978 boilerplate that was
reported by the idnits tool. This will be fixed in the subsequent
revision.

(1.h) Has the document split its references into normative and
informative? 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
strategy for their completion? Are there normative references
that are downward references, as described in [RFC3967]? If
so, list these downward references to support the Area
Director in the Last Call procedure for them [RFC3967].

The document splits its references into normative and informative.
In Normative References, [3]'s WGLC ended on October last year
and several comments as well as expert reviews happened to this
document. After revision, it will be ready for advancement soon.

(1.i) Has the Document Shepherd verified that the document IANA
consideration section exists and is consistent with the body
of the document? If the document specifies protocol
extensions, are reservations requested in appropriate IANA
registries? Are the IANA registries clearly identified? If
the document creates a new registry, does it define the
proposed initial contents of the registry and an allocation
procedure for future registrations? Does it suggested a
reasonable name for the new registry? See
[I-D.narten-iana-considerations-rfc2434bis]. If the document
describes an Expert Review process has Shepherd conferred with
the Responsible Area Director so that the IESG can appoint the
needed Expert during the IESG Evaluation?

The IANA considerations section exists. This document has no
actions for IANA.

(1.j) Has the Document Shepherd verified that sections of the
document that are written in a formal language, such as XML
code, BNF rules, MIB definitions, etc., validate correctly in
an automated checker?

Does not apply to this document.

(1.k) The IESG approval announcement includes a Document
Announcement Write-Up. Please provide such a Document
Announcement Writeup? Recent examples can be found in the
"Action" announcements for approved documents. The approval
announcement contains the following sections:

Technical Summary
Relevant content can frequently be found in the abstract
and/or introduction of the document. If not, this may be
an indication that there are deficiencies in the abstract
or introduction.

Relevent content can frequently and easily be found in the abstract and
introduction of this document. This document explains different IPv6 link
models that are suitable for 802.16 based networks and analyzes them
and their applicability under different deployment scenarios.

Working Group Summary
Was there anything in WG process that is worth noting? For
example, was there controversy about particular points or
were there decisions where the consensus was particularly
rough?

None.

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?

This document suggests a couple of link model to be used for 802.16
networks. Ethernet like link model would be used when the deployment
requires the use of Ethernet CS. For IPv6CS, point-to-point link model
appears to the choice because of its simplicity for performing the DAD
and does not break any existing applications or require defining any
new protocol. Those will be implemented in 802.16 networks soon.
The quality of the document is good.

Personnel
Who is the Document Shepherd for this document? Who is the
Responsible Area Director?

Daniel Park is the Document Shepherd for this document.
Jari Arkko is the Responsible Area Director.

==============================================================

Daniel (Soohong Daniel Park)
Mobile Convergence Laboratory, SAMSUNG Electronics.