OSPFv2 Multi-Instance Extensions
draft-ietf-ospf-multi-instance-09

[Ballot comment]
Yep, I agree with all the "what a hack" comments. OTOH, I
do agree that its not likely that a 256th auth type will be
needed here.

I also agree that the abstract is very unclear and should be
rewritten.

[Ballot comment]
I'm with Peter on this draft - I too lack the background and ultimately trust that the AD is doing the right.  But, I am curious why this wouldn't be a version # change especially if it affects all implementations.

[Ballot comment]
Although the authors appear to have documented the interoperability implications of reducing the AuType field from 2 octets to 1 octet, that still feels like a hack to me. However, I lack the context to judge whether the implications have been fully understood or documented. (Note also that this issue is not even mentioned in the shepherd writeup!)

[Ballot discuss]
1. In Section 3:

> Its setting to a non-zero value may be accomplished through configuration
  or implied by some usage beyond the scope of this document.

I have no clue what 'implied by some usage beyond the scope of this document'. An example clarifying this would be helpful.

2. In Section 6:

> Previously, there was concern that certain implementations would log
  every single authentication type mismatch.  Additionally, if
  ospfIfAuthFailure SNMP generation is enabled as specified in
  [OSPF-MIB], a separate trap would be generated for each received OSPF
  packet with a non-zero Instance ID.  However, discussions with
  implementers have led us to the conclusion that this is not as severe
  a problem as we'd first thought and it will be even less of a problem
  by the time the mechanism in this draft is standardized, implemented,
  and deployed.  Most implementations will dampen both the logging of
  errors and the generation of identical SNMP traps.  Hence, the more
  drastic mechanisms to avoid legacy OSPF routers from receiving
  multicast OSPF packets with non-zero Instance IDs have been removed.

This does not work. 'this is not as severe a problem as we'd first thought' is not good enough - having a notification generated or a long entry created for each authentication type mismatch or even throttled once a second or once a minute is a problem.

Luckily for SNMP notifications (please use this more generic term rather than trap) there is a solution if together with the OSPFv2 MIB (RFC 4750) is implemented, also the SNMP-NOTIFICATION-MIB in RFC 3413 is implemented, and the ospfIfAuthFailure and ospfVirtIfAuthFailure notifications are being disabled using the entries in the SnmpNotifyFilterTable. I suggest to add this recommendation for all routers that implement RFC 4750.

[Ballot comment]
I have a few additional Comments that I think would improved the
document and I hope you will consider incorporating them into a new
revision.

---

The Abstract is very dense. Nothing wrong with what you have written,
but it's quite hard work. How about...

  OSPFv3 includes a mechanism to support multiple instances of the
  protocol running on the same interface.  OSPFv2 can utilise such a
  mechanism in order to support multiple routing domains on the same
  subnet.

  This document defines the OSPFv2 instance ID to enable separate
  OSPFv2 protocol instances on the same interface.  Unlike OSPFv3 where
  te instance ID can be used for multiple purposes, such as putting the
  same interface in multiple areas, the OSPFv2 instnce ID is reserved
  for identifying protocol instances.

  This document updates RFC 2328.

Note that I have left out of the Abstract the statementabout how a
different funciton is supported by a diffenent protocol extension defined
in a different document!

---

You are inconsistent about whether to say "OSPF" or "OSPFv2" when
refering to OSPFv2. Given that you keep comparing to OSPFv3, I think it
would be helful to always say "OSPFv2".

---

You use phrases such as "OSPFv2 currently doesn't offer" which are, of
course, correct before this becomes an RFC, whereupon they become wrong.
If you can avoid this sortof thing by saying "This document defines..."
then the draft is future-proofed.

---

Can you please replace the future tense with the present tense. For
example, Section 3

  OSPF [OSPFV2] describes the conceptual interface data structure in
  section 9.  The OSPF Interface Instance ID will be added to this
  structure.  The OSPF Interface Instance ID will default to 0.

---

Section 3.1

  When sending OSPF packets, if the OSPF Interface Instance ID has a
  non-zero value, it will be set in the OSPF packet header.

Surely the zero value is also set in the packet header. That is, the
field is not left uninitialised.

[Ballot discuss]
I would be happy to ballot Yes on this document, but there are a couple
of minor areas where I think the document needs work.

---

I have a hot button about redrawing and redefining protocol fields.
There is a risk in this duplicaton, and problems for future extensions.
Your figure in Section 2 reproduces material from RFC 2328. How much of
this is necessary? Is it helpful to sometimes say that a field is "as
specified in [OSPFV2]" and sometimes write text that duplicates RFC 2328
without actually changing anything?

I think you might get away with the figure and text that says:

  All fields are as defined in [OSPFV2] except that the Instance ID
  field is new, and the AuType field is reduced to 8 bits from 16 bits
  without any change in meaning. The Insatnce ID fiels is interpreted as
  follows:

---

In Section 8 you need to inform IANA that you have reduced the available
range of values for AuType. This changes the registry.

---
                                                                       
The registry in Section 8 shows a number of instance ID value settings
(namely "Base IPv4 Multicast", "Base IPv4 In-band Management Instance",
and "Local Policy") without any discussion of the meaning in this
document. That will not do! You must add description of the meaning of
these settings somewhere in the body of the document.

---

Section 8 describes the allocation policy for the range 3-127 as
"Reserved for local policy assignment". There is no such allocation
policy in RFC 5226. Do you mean "Private Use"? It is hard for me to
guess given the totla lack of description of this range of settings as
noted in my previous point.

Upon approval of this document, IANA will create the following registry
at http://www.iana.org/assignments/ospfv2-parameters

Registry Name: OSPF Instance IDs
Registration Procedure: Standards Action
Reference: [RFCXXXX]

| Value      | Designation          |
+-------------+----------------------+
| 0          | Base IPv4 Unicast    |
|            | Instance            |
|            |                      |
| 1          | Base IPv4 Multicast  |
|            | Instance            |
|            |                      |
| 2          | Base IPv4 In-band    |
|            | Management Instance  |
|            |                      |
| 3-127      | Local Policy        |
|            |                      |
|            |                      |
| 128-255    | Unassigned          |

State changed to In Last Call from Last Call Requested.

The following Last Call Announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (OSPF Multi-Instance Extensions) to Proposed Standard


The IESG has received a request from the Open Shortest Path First IGP WG
(ospf) to consider the following document:
- 'OSPF Multi-Instance Extensions'
  as a 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 2011-12-12. 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


  OSPFv3 includes a mechanism for supporting multiple instances on the
  same interface.  OSPFv2 could benefit from such a mechanism in order
  to support multiple routing domains on the same subnet.  The OSPFv2
  instance ID is reserved for support of separate OSPFv2 protocol
  instances.  This is different from OSPFv3 where it could be used for
  other purposes such as putting the same interface in multiple areas.
  OSPFv2 supports this capability using a separate subnet or the OSPF
  multi-area adjacency capability.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-ospf-multi-instance/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-ospf-multi-instance/


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

  (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?

        Manav Bhatia, Yes

  (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? 

Yes, No

  (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?

No

  (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. Has an IPR disclosure related to this document
        been filed? If so, please include a reference to the
        disclosure and summarize the WG discussion and conclusion on
        this issue.

No

  (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? 

This draft is describing a mechanism to support multiple
        routing domains on the same subnet, a mechanism that already
        exists in OSPFv3. It modifies the OSPF packet header and takes
        8 bits from the 16 bits of Authentication Type to indicate the
        Instance ID. The mechanism described in this draft is backward
        compatible with routers that cannot support multiple instances.

There is strong consensus in the WG behind this draft.

  (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 the Internet-Drafts Checklist
        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?

Yes

  ------------------------------------------------------------------------

  idnits 2.12.12

  tmp/draft-ietf-ospf-multi-instance-06.txt:

  Checking boilerplate required by RFC 5378 and the IETF Trust (see

  http://trustee.ietf.org/license-info):

------------------------------------------------------------------------

    No issues found here.

  Checking nits according to http://www.ietf.org/id-info/1id-guidelines.txt:

------------------------------------------------------------------------

    No issues found here.

  Checking nits according to http://www.ietf.org/id-info/checklist :

------------------------------------------------------------------------

  -- The draft header indicates that this document updates RFC2328, but the
    abstract doesn't seem to mention this, which it should.

  Miscellaneous warnings:

------------------------------------------------------------------------

    No issues found here.

  Checking references for intended status: Proposed Standard

------------------------------------------------------------------------

    (See RFCs 3967 and 4897 for information about using normative references
    to lower-maturity documents in RFCs)

    No issues found here.

    Summary: 0 errors (**), 0 warnings (==), 1 comment (--).

    Run idnits with the --verbose option for more detailed information about
    the items above.

------------------------------------------------------------------------

  (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].

Yes, No

  (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 suggest a
        reasonable name for the new registry? See [RFC5226]. 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?

Yes (to all questions above)

  (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?

Yes

  (1.k) 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 draft extends OSPFv2 to support multiple routing domains
    on the same subnet - a capability that already exists in OSPFv3.
    This is different from OSPFv3 where it could be used for
    other purposes such as putting the same interface in multiple areas.
    OSPFv2 supports this capability using a separate subnet or the OSPF
    multi-area adjacency capability.

    Working Group Summary

    The only discussion worth noting was the behavior of
    legacy routers receiving OSPF packets with non-Zero instance
    ID. It was concluded that the such packets would be
    misinterpreted as having mismatched authentication type
    and would get dropped. Such errors should get logged and
    should result in the generation of SNMP traps. There was
    concern that this could be an issue if every packet would
    result in SNMP trap generation. However, it was discussed that
    this will not be an issue since most implementations will damp
    the logging of errors and generation of identical SNMP traps.

    Document Quality

    There is one known implementation.