Bidirectional Forwarding Detection (BFD) Management Information Base
draft-ietf-bfd-mib-22

[Ballot comment]
The document says it doesn't create a compliance requirement for v0.  Does it define a compliance requirement for v1? Should this document update that RFC?

[Ballot comment]
  In particular, it describes managed objects to configure and/or
  monitor Bidirectional Forwarding Detection for [RFC5880], [RFC5881],
  [RFC5883] and [RFC7130], BFD versions 0 and/or 1, on devices
  supporting this feature.

bfdSessVersionNumber OBJECT-TYPE
        SYNTAX    Unsigned32 (0..7)
        MAX-ACCESS read-create
        STATUS    current
        DESCRIPTION
            "The version number of the BFD protocol that this session
            is running in. Write access is available for this object
            to provide ability to set desired version for this
            BFD session."

So the MIB module is for BFD version 0 and 1, but I can set the version to [0..7].
What does it mean to set the value to 6?
What is the likelihood that version [2..7] have the exact same set of arguments? So anyway we would need an updated MIB module.

Discussing this matter with Bert Wijnen, a proposal would be to add to the description clause that only valid versions as supported by the implementation can be accepted. Others would return an error.

And finally, valid question from Bert: if you prepare for the future, why limit this to max version 7, and not 256?

[Ballot comment]
Section 6:
"Even if the network itself is secure "for example by using IPSec",
  even then, there is no control as to who on the secure network is
  allowed to access and GET/SET "read/change/create/delete" the objects
  in these MIB modules."

I don't understand what is being quoted here. Also, I think what is meant here is that IPSec itself does not provide access control, not that "there is no control." I would suggest something like:

Even if IPSec is used to secure network traffic, it does not provide control over who on the network is allowed to access and GET/SET "read/change/create/delete" the objects in these MIB modules.

"It is RECOMMENDED that implementers consider the security features as
  provided by the SNMPv3 framework (see [RFC3410], section 8),
  including full support for the SNMPv3 cryptographic mechanisms "for
  authentication and privacy"."
 
Again I don't understand what is being quoted here.

[Ballot discuss]

I'm not sure if a text change will be needed for this discuss or
not, I'd like to understand it better before I'd suggest one in any
case.

The security considerations says:

"The bfdSessAuthenticationType, bfdSessAuthenticationKeyID, and
bfdSessAuthenticationKey objects hold security methods and
associated security keys of BFD sessions.  These objects SHOULD be
considered highly sensitive objects.  In order to prevent this
sensitive information from being improperly accessed, implementers
MAY disallow access to these objects."

I don't understand why these SHOULD (and not MUST) be considered
highly sensitive - maybe that's just me not knowing enough about
MIBs though - what's the logic there? Allowing access to a
cleartext key that can then by used to muck with routing seems like
a bad plan in all cases. Also, if you said they MUST be considered
highly sensitive can you say what that'd mean in practice that's
different from the current SHOULD? (Maybe the MAY in the 2nd
sentence would change?) Finally, if you keep the SHOULD, then what
is the counterexample that justifies the SHOULD rather than a MUST?

[Ballot comment]


I didn't quite get the meaning of this:

"The Authentication Type used for this BFD session.  This field is
valid only when the Authentication Present bit is set. Max-access
to this object as well as other authentication related objects are
set to read-create in order to support management of a single key
ID at a time, key rotation is not handled. Key update in practice
must be done by atomic update using a set containing all affected
objects in the same varBindList or otherwise risk the session
dropping."

That's in the definition of bfdSessAuthenticationType. Can you
explain? (Its probably just my ignorance of SNMP though;-)

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-bfd-mib-17.  Authors should review the comments and/or questions below.  Please report any inaccuracies and respond to any questions as soon as possible.

IANA's reviewer has the following comments/questions:

IANA understands that, upon approval of this document, there is
a single action which IANA must complete.

In the SMI Network Management MGMT Codes Internet-standard MIB registry
in the Network Management Parameters registry located at:

http://www.iana.org/assignments/smi-numbers

a new MIB will be registered as follows:

Decimal: [ TBD by IANA at time of registration ]
Name: bfdMIB
Description: Bidirectional Forwarding
References: [ RFC-to-be ]

IANA understands this to be the only action required of IANA upon
approval of this document.

IANA requests that the IANA Considerations section of the document remain in place upon publication.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (BFD Management Information Base) to Proposed Standard


The IESG has received a request from the Bidirectional Forwarding
Detection WG (bfd) to consider the following document:
- 'BFD Management Information Base'
  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 2014-04-28. 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 draft defines a portion of the Management Information Base (MIB)
  for use with network management protocols in the Internet community.
  In particular, it describes managed objects for modeling
  Bidirectional Forwarding Detection (BFD) protocol.

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

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

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

AD review
=======

Hi authors of draft-ietf-bfd-mib,

I have done my usual AD review after receiving a publication request.
The purpose of the review is to catch issues that would show up during
IETF last call or IESG review and so save the reviewers some time and
get the quality up to a level that is acceptable.

This document represents a lot of work: thank you. The issues I have
found are relatively small. Some of them take the form of questions and
you can answer these with email rather than feeling compelled to make
documentation changes. Furthermore, all of the issues are open for
discussion.

I will put the document into "Revised I-D" state and wait to hear back
from you.

Thanks,
Adrian

===

You'll obviously want to make updates to accommodate changes to
draft-ietf-bfd-tc-mib

---

Tom may want to change his coordinates.

---

Could you swap sections 1 and 2 so that the document starts with the
Introduction.

---

Section 2

s/an portion/a portion/

---

Section 4.4

I don't think the table maps a discriminator to a TC. Maybe it maps the
discriminator to the session or the session index or something.

The same thing shows up in some of the Description clauses, for example,
bfdSessDiscMapTable

---

Similarly 4.5

---

It is nice if you name the RFCs in comments next to the import clauses.

---

If I am creating an entry in bfdSessTable (and it seems that I can since
most of the objects are read-create) how do I know what value to pick
for bfdSessIndex?

A way to handle this is through a "next available index" global object.

---

bfdAdminStatus is ambiguous!
Does setting bfdSessAdminStatus to "start" mean that the session is up
or only that the implementation will attempt to bring it up?
The normal approach is to have adminStatus described as "the desired
operational status" and a separate object reports the actual operStatus.
Since you have bfdSessOperMode, I think this is your intention.

---

bfdSessState and bfdSessRemoteHeardFlag are read-only. What does it mean
to have default values?

---

Doesn't bfdSessMultipointFlag need a reference to the document that
defines multipoint BFD? If so, doesn't that create a normative reference
gate for this MIB module? That means you either take multipoint out or
you will have to wait until it completes the process.

---

You appear to have two mechanisms to turn off GTSM

    bfdSessGTSM OBJECT-TYPE
        SYNTAX  TruthValue
        DESCRIPTION
          "Setting the value of this object to true(1) will enable GTSM
            protection of the BFD session.
... So presumably setting it to false will disable GTSM. But...


    bfdSessGTSMTTL OBJECT-TYPE
        SYNTAX Unsigned32 (0..255)
        DESCRIPTION
            The value of zero(0) indicates that
            bfdSessGTSM is disabled."

---

bfdSessAuthPresFlag has a default of false indicating that no
authentication is to be used. And bfdSessAuthenticationType has a
default of -1 meaning no authentication is in use. Doesn't that mean
that the default for bfdSessGTSM should be true and the default for
bfdSessGTSMTTL should be non-zero?

---

Why don't objects like bfdSessDesiredMinTxInterval have default values?

---

Shouldn't the default for bfdSessAuthenticationType be noAuthentication
not -1?

---

I am unsure about how the three objects for authentication work.

bfdSessAuthenticationType and bfdSessAuthenticationKeyID say that they
must be -1 if bfdSessAuthPresFlag is false.

Now, suppose I want to turn on authentication. I want to set
bfdSessAuthPresFlag to true, but if I do, the settings of
bfdSessAuthenticationType and bfdSessAuthenticationKeyID are bogus.
But if I want to set bfdSessAuthenticationType and
bfdSessAuthenticationKeyID to real values in preparation to setting
bfdSessAuthPresFlag to true then I will have broken the rule.

The only option appears to set all three objects at once (which is
possible only depending on implementation).

---

I'm surprised that entries in bfdSessDiscMapTable are writeable.
That is to say, that bfdSessDiscMapStorageType and
bfdSessDiscMapRowStatus exist and are writeable. Surely this table
is automatic and entries an artifice of entries in bfdSessTable.
                                         
Why would you want an entry in this table to have a different
storage type or row status from those in bfdSessTable?

What does it mean that those two objects are creatable? Does it mean
that you can create an entry in this table without knowing the value
of bfdSessDiscMapIndex which is automatic?

Same questions about bfdSessIpMapTable

---

The Security section says...

  The bfdSessAuthenticationType, bfdSessAuthenticationKeyID, and
  bfdSessAuthenticationKey objects hold security methods and associated
  security keys of BFD sessions.  These objects SHOULD be considered
  highly sensitive objects.  In order for these sensitive information
  from being improperly accessed, implementers MAY wish to disallow
  read and create access to these objects.

You don't want to prevent write access as well?
                                                                 
But note that preventing read access is pretty much not having the
object. So why *do* you have the objects and then suggest not providing
any access to them?

: Document Writeup
:
: 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.  The draft meets the criteria in RFC 2026, Sec. 4.1.1.
The type is properly indicated in the title page 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

  This memo defines an portion of the Management Information Base (MIB)
  for use with network management protocols in the Internet community.
  In particular, it describes managed objects to configure and/or
  monitor Bi-Directional Forwarding Detection for [RFC5880], [RFC5881]
  and [RFC5883], BFD versions 0 and/or 1, on devices supporting this
  feature.

Working Group Summary

  This document received commentary from multiple individuals that have had
  prior SNMP MIB authoring and implementation experience.  The document was
  also reviewed in the context of additional BFD work besides providing
  base MIB functionality for the above RFCs.  This includes BFD
  multi-point, BFD over LAG.  It also has been reviewed as being the basis
  MIB for the BFD MPLS MIB.

Document Quality

  As is typical with MIB documents, several vendors implement the contents
  of the BFD MIB in various enterprise MIBs with greater or lesser
  attention paid to the exact structure of this document.  MIBs are seldom
  fully finished at vendors until the publication of the MIB as an RFC
  wherein all the code points are finalized with IANA and other
  authorities.

  In particular, the Textual-Convention draft covers various TCs that do
  not share consistent implementations across the vendors.  By publishing
  an RFC, these code points will become normalized across the vendors.

  Being a MIB document, review by the MIB doctors is always appreciated.

Personnel

  Document Shepherd: Jeffrey Haas
  Responsible AD: Adrian Farrel

: (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.

I reviewed the MIB documents for structural and language content multiple
times throughout their life cycle.  Additionally, I also requested targeted
review of the contents and structure with interested reviewers at the Berlin
IETF.

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

No concerns.

: (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.

While there has been a general distancing of MIBs from write-capable
behaviors within the IETF routing area, this MIB does contain objects that
are read-create.  Unlike other far more complex protocols, basic BFD is
simple enough from a data modeling standpoint that the MIB can potentially
be used to provision BFD using SNMP.  As such, this does warrant additional
review from both a security and operational complexity perspective.

As is typical with routing protocol components, particularly those used for
OAM functionality, BFD is not terribly useful in a standalone environment.
It is thus expected that while the protocol can be provisioned using the
read-create objects within the MIB that many environments would not be able
to fully take advantage of such a provisioning system due inter-protocol,
and thus inter-MIB table dependencies.  This, however, is not a deficiency
of this MIB but rather a well known issue of the MIB ecosystem.

: (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.

I have no ongoing concerns.

: (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 3 authors have positively affirmed that they have done all necessary IPR
disclosures - there are none.

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

No IPR has been filed and all authors affirm there is no IPR attached to
this document.

: (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? 

For a MIB, this document has received substantial review by the working group.

The WG has consensus that this document should be published.

: (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 appeals have been threatened and discontent has been confined to minor
concerns about future MIBs that may need to be based upon this base MIB.
Those concerns appear to have been addressed as partof WGLC comments.

: (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.

The ID-nits tool has run clean on the MIB drafts.

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

MIB Doctor review has not yet been done.

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

They have.

: (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?

All normative references are currently published RFCs.  For the base BFD
MIB, the remaining normative reference is the TC MIB, also being submitted
for publication with the base MIB.

: (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).

The documents were reviewed after WGLC to request IANA to adopt these as
IANA maintained MIBs.  An additional short WGLC-bis was requested to double
check the resulting object and TC renames.

: (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.

In the base BFD MIB, no additional registries are requested.

For the BFD TC MIB, there is a desire to publish the TC MIB as an IANA
maintained MIB. 

: (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.

Per the mib-review-tools, the drafts pass smilint.  I do not have access to
smicng.