Mesh Link Establishment
draft-kelsey-intarea-mesh-link-establishment-06

From the author:

Please mark it dead.  It was part of the ZigBee IP effort, which is fading into oblivion.  It can be revived if and when it has an active constituency within an IETF working group.

I greatly appreciate your efforts, and the efforts of the reviewers.

[Ballot discuss]
I'm not familiar with 802.15.4 security sorry, so you
may need to educate me a bit, and I had to review this
in a hurry so might be wrong below (and sorry again:-)
but I had the following questions to discuss:

(1) I don't get why its ok that there is no key
management defined, either here or somewhere else via
reference. That could be fixed via some more text in
section 3 perhaps, if there are other specs that do
define how to do key management, e.g. to reference one
(or more) that do define that and to say that other
uses of this need to do similarly. Absent that, maybe
we're back to looking at BCP107, but I'm not sure we
want to (or hopefully, need to:-) go there.

(2) The overall security model is a bit complicated, I
wasn't clear whether the combinations of security
being on and off (i.e. initial byte = 0 or 255) adds
up to a good outcome. There are also cases (e.g.
joining) where where MLE security MUST NOT be used but
link layer MUST be used.  Has someone done an analysis
of how that all stacks up together? Can you point me
at that? (Sorry for the fairly vague question.)

(3) As a particular case of (2), I don't get how the
device joining without any keys thing is meant to
work, nor under exactly what conditions. Don't you
need to specify this or at least state the
requirements for it to work if specified elsewhere?

(4) I'm not clear that the frame counter + key cannot
repeat, esp. since we don't have the key management
detail here and that there seems to be a way for one
node to tell another which frame counter value to
start from (is that right or is that just telling a
new peer what my current frame counter is at? If the
latter, why not just get that by observation?). I do
see you say that they MUST NOT be repeated, but if
there are shared keys over >1 device, or, if its
allowed to not use the same frame counter for link and
MLE but is allowed to use the same key, then that may
not be implementable.

[Ballot discuss]
I am sorry that I have only had time for a very brief review of this document. I should be happy if you are able to say that any of my Discuss points is rubbish based on my reading too fast.

-------

Section 4

  The purpose of the third, detecting neighboring
  devices, is to make link management more efficient by detecting
  unreliable links before any effort is spent configuring them.


Do you not think "detecting neighbor devices" is an odd name for a
feature which is intended to detect unreliable links before any effort
is spent configuring them?

Similarly the title of section 4.3.

Isn't this link discovery? (A link not being an interface :-) For
example, suppose there are two links that reach the same neighbor?


But in section 8...
  Link configuration
  and advertisement messages MUST be sent with an IP Hop Limit of 255,
  either to a link-local unicast address or to the link-local all-nodes
  (FF02::1) or all-routers (FF02::2) multicast addresses.

...I believe that what you are defining is effectively a link state
protocol by full flooding. This is not a discovery protocol. I am very
wary of such a protocol being defined (we have been there before and it
sucks!)

At the very least, this document needs to be clear whether it is a
discovery protocol, a link parameter negotiation/discovery protocol, or
a link parameter flooding protocol. In the latter case, I would like the
document to explain the scope and purpose of this wholesale flooding.

On the other hand, part of the problem may be that you intend that MLE
should be able to send (from a central location) configuration
information that is to be used at each node (or some set of nodes) in
the network. Section 11 gives this hint. Yet that is a very different
use of the protocol and many features of that operation (such as how
thrashing between two senders is handled) are left for the reader to
ponder.

---

Section 5 needs to indicate how a parser knows the length of an MLE
message. How do I know when to stop parsing TLVs and start parsing the
MIC (in the 0 case) or stop parsing the message (in the 255 case).

---

Section 7

  With the exceptions of the Source Address TLV and Parameter TLV, an
  MLE message MUST NOT contain two or more TLVs of the same type.

You need to say how such errors are handled.

However, I think you have hamstrung yourself for the future. Why not add
a column to the registry that says "Multi-occurrence allowed" and then
state that RFCs defining new TLVs must state whether multiple occurrences
are allowed.

---

Section 7.1

  The Source Address TLV (TLV Type 0) has a Value containing a byte
  string representing a link-layer address assigned to the source of
  the message.

Does "a byte string representation" have a specific meaning in the
context of IEEE 802.15.4? To me it is not specific enough to write code.

---

Section 7.6

"encoded as an N-bit unsigned integer."

This is curious as the TLV length can only indicate full octet lengths.

Is N allowed to be other than an integer multip of 8?

---

Section 7.7

  Size                The size in bytes of the included neighbor link-
                      layer addresses, minus 1.  This supports
                      addresses of lengths 1 to 16 bytes.

This is ambiguous. Do you mean the total size of all addresses, or the
size of a single address with the requirement that all addresses must be
the same size?

Yet later in the same description of the data format...

  Address            A link-layer address of a neighbor.

... which says that only one address is present (and misnames the field
compared to the figure).

---

Section 7.8

  Value              A byte string containing the new value of the
                      parameter.  The format of this value is
                      determined by the particular parameter

And yet the formats don't appear to be described when the parameters
are listed later in the section.

---

7.9.  MLE Frame Counter

  The MLE Frame Counter TLV (TLV Type 8) has a Value containing the
  sender's current outgoing MLE Frame Counter, encoded as an 32-bit
  unsigned integer.

What is an MLE frame? Is this a count of messages or L2 frames or...?
How does this wrap?
When is it reset?
Is the 32 bit integer in line format?

Section 5 gives some information about this with cross-pointers to [CCM]
Section 9 tells us how to handle received frame counters.
But 7.9 needs to point to these other sections, and Section 8 should
explicitly state about setting the counter.

[Ballot comment]
I wish this document had been scrubbed for acronym expansion so that I
could have reviewed it more easily.

---

Section 1

  MLE can also be used to distribute configuration values that are
  shared across a network, such as the channel and PAN ID.  Network-
  wide configuration uses multicasts and requires some form of multi-
  hop multicast forwarding.  These messages are sent infrequently, so
  forwarding with simple flooding is sufficient.

This is a confusing paragraph:
- "MLE can also be used..."
  There has been no previous mention of MLE. What does "also" mean?
- "Network-wide configuration uses..."
  Do you mean "MLE uses..."
- "These messages...."
  Which messages?

---

I find the definition of ETX confusing. You have...

  ETX                Expected Transmission Count [RFC6551]; the number
                      of transmission attempts required to send a
                      packet over a particular link.  Defined to be the
                      product of the IDR values for both directions.  A
                      perfect link has an ETX of 1, less than perfect
                      links have higher ETX values.

If ETX is the product of IDR in both directions then ETX is a complex
characteristic of both directions of the link. Yet the definition says
the number of transmission attempts required to send *a* packet. A
single packet is, of course, sent in a single direction and the quality
of the link in the other direction doesn't matter. But, presumably,
since you want ETX to be a characteristic of both diretions you need to
rephrase this definition.

---

Section 4

  MLE adds three capabilities to IEEE 802.15.4:

  o  Dynamically configuring and securing radio links.

I don't believe MLE secures links. I believe MLE exchanges parameters
for the SA between link ends that allows security to be used on the
link.

---

Section 4.2

  Network-wide changes to radio parameters, such as moving the network
  to a new channel, is done by multicasting the new value(s) to all
  devices in the network.

Really? All devices in the network?
Surely a device 27 hops away is less than interested in the channel
being used on this link.

---

I find Section 5 confused/confusing.

The section seems to have two purposes:
- defining the MLE message formats
- describing how the MLE messages may themselves be secured.

It may be as simple as fixing the section title and tweaking the text.

---

Section 5

  [CCM] requires that each key and nonce pair be
  used exactly once

You mean for just one packet? No, you don't! Please clarify the text.

---

It would be nice if Section 6 pointed to Section 14.2

---

Section 7.4

  The recommendations in [RFC4086] apply with
  regard to generation of the challenge value.

and

  This is done by sending a random challenge value

These to statements may be interpretted as conflicting. At best you
are saying the same thing twice.

---

While the Link-layer Frame Counter in section 7.6 probably has well-
known meaning to those in the know, I think you need more description
to let coders understand what they are supposed to put in one of these
TLVs.

---

Section 7.7

  Res                Reserved; MUST be set to 000 and SHOULD be
                      ignored on receipt.

Normally the MUST and SHOULD are the other way around.
In this spec, why would you not ignore the received reserved field that
has been set to zero?

---

Section 8

  MLE messages SHOULD be sent using the assigned UDP port number
  (19788) as both the source and destination port.

Are you sure you want to confine the source port in this way? In general
this turns out to be a mistake.

---

Section 9

  Incoming messages whose Command Type is a reserved value MUST be
  ignored.  Any TLVs in an incoming message whose TLV Type has a
  reserved value MUST be ignored.

I think "reserved" means "unknown" or "unsupported" in both cases.

[Ballot discuss]
The draft seems okay, although I'd like to understand why there isn't a stronger requirement around replay protection or see that fixed with stronger language.  The Security Considerations section says:

  Because of this, implementers must
  be careful in how they use information obtained from these possibly-
  replayed messages.  For example, information from unsecured messages
  should not be used to modify any stored information obtained from
  secured messages.

and section 7.4 provides a way to do this with a challenge:

  The recommendations in [RFC4086] apply with
  regard to generation of the challenge value.  The byte string MUST be
  at least 4 bytes in length and a new value MUST be chosen for each
  Challenge TLV transmitted.  An important part of replay protection is
  determining if a newly-heard neighbor is actually present or is a set
  of recorded messages.  This is done by sending a random challenge
  value to the neighbor and then receiving that same value in a
  Response TLV sent by the neighbor.

[Ballot comment]
The draft seems okay, although I'd like to know why there isn't a stronger requirement around replay protection.  The Security Considerations section says:

  Because of this, implementers must
  be careful in how they use information obtained from these possibly-
  replayed messages.  For example, information from unsecured messages
  should not be used to modify any stored information obtained from
  secured messages.

and section 7.4 provides a way to do this with a challenge:

  The recommendations in [RFC4086] apply with
  regard to generation of the challenge value.  The byte string MUST be
  at least 4 bytes in length and a new value MUST be chosen for each
  Challenge TLV transmitted.  An important part of replay protection is
  determining if a newly-heard neighbor is actually present or is a set
  of recorded messages.  This is done by sending a random challenge
  value to the neighbor and then receiving that same value in a
  Response TLV sent by the neighbor.

[Ballot discuss]
I have no objection to the publication of this document, but there are some points that need work...

1. In section 6, it is unclear as to how Command Type 2 differs from a combination of Command Types 0 and 1.  In what instances would a sender use Command Type 2?  It seems to me that this *could* be an exchange like: 1) A sends CT==0 to B, 2) B sends CT==2 to A, and 3) A sends CT==1 to B.  Is that the expected usage?  If so, it should be explained.  I was expecting to see Section 10 do that, but that didn't materialize.

2. Some of the specified Command Types and TLVs are obviously link-local in nature.  Are there Command Types and TLVs that are only network-wide?  I would like to see some description of how far each of the Types and TLVs should be propagated.

3. This is related to Barry's comment about destination address selection.  Section 8 should tighten up the guidance on address selection.  This should be tied to the point raised in #2 above, in that the destination address needs to take the scope of the information contained in the message into account.

4. It is unclear to me what Section 9 is saying about "reserved Command Types" and "reserved TLV Types".  Are those just values that are not recognized?

[Ballot comment]
I have a couple of questions about the use of 2119 "MAY" below; I think it's important to resolve them, so please consider these comments.

-- Section 8 --

  Update
  messages MAY be sent as above, or MAY be sent to a site-local all-
  MLE-nodes multicast address (to be assigned by IANA).

Or they may be sent in any other way, as those "MAY"s specify optional behaviour -- so you MAY also do neither.  Is that the intent?  Or is the intent that one can choose, at one's option, between those two choices, but no other?

If that's what's meant, let me suggest this instead:

NEW
  Update
  messages MUST either be sent as above, or be sent to a site-local
  all-MLE-nodes multicast address (to be assigned by IANA).
END

What is the line that says "MAX_RESPONSE_DELAY_TIME  1 second" meant for?  Should there be some other text around it?

Similarly for the table: should the previous paragraph have an additional sentence that says, "The following are recommended default values for relevant timeout and retransmission parameters."?  I think this would read better with an explanation such as that.

-- Section 10 --

  If large numbers of Link Request messages arrive
  a device MAY reduce or completely suspend sending Link Accept
  messages, and MAY send Link Reject messages instead.

This is a similar double-MAY to the previous one, and it brings up a similar question: as written, it says:
1. If large numbers of Link Request messages arrive, a device has the option of reducing or completely suspending sending Link Accept messages.
2. If it does that, it has the option of sending Link Reject messages instead.  It also has the option of not sending Link Reject messages instead.  It could, for example, not respond at all, or respond in some other way.

Is that what's intended?  Or is it intended that if it stops sending Link Accepts, it will always send Link Rejects?  If so, then just removing the second "MAY" will fix it.

(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?

i) Type of RFC Requested: Proposed Standard
ii) It is the proper type of RFC because the document describes a
communications protocol
iii) The type of RFC is 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:

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.

MLE is a protocol for link-layer configuration, including link layer
addressing, transmit and receive modes, wake/sleep cycles and security. 
Its use in ad hoc mesh networks is complementary to existing IETF
neighbor discovery protocols, such as IPv6 ND [RFC4861] and NHDP
[RFC6130].  MLE can be used to configure individual links and to
distribute configuration values that are shared across a network. 
Per-link configuration uses one-hop messages with link-local addresses.
Network-wide configuration uses multicasts and requires some form of
multi-hop multicast forwarding.  MLE resolves the issue of determining
two-way link quality between nodes in a lossy network (e.g. wireless) by
allowing a node to periodically multicast an estimate of the quality of
its links.  This allows a node to determine if it has a usable link to a
neighbor without first configuring that link.

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?

Due to the general nature of the protocol and its application to link
layer technology, there was no particular WG which suited the draft. It
has been discussed in the 6lowpan and roll WG mailing lists. The only
controversy notable was the use of UDP as the base protocol for MLE.
Some suggested ICMPv6 would be more appropriate tied to RPL messages,
however this had the criticism of narrowing the scope of MLE, which has
been written without any specific IETF protocol in mind.

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?

There are numerous existing implementations of the protocol as it is
currently being adopted and tested by ZigBee Alliance members involved
in the development of the ZigBee IP stack. There are currently 7
independent vendors implemeting the protocol. Thomas Clausen has
performed a thorough review of draft version 02 and his comments have
been incorporated in version 03 onwards.

Personnel:

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

The Document Shepherd is Robert Cragie. The Responsible Area Director is
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 Document Shepherd and Responsible Area Director have reviewed the
draft document and have been party to the interoperability testing
events undertaken by the vendors to confirm interoperable implementation
of the protocol and its fitness for purpose.

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

The document has been submitted for review on all relevant WG mailing
lists and has had discussion. It has also been through practical
implementations subject to continuous review by the implementors, who
have fed back comments to the author, who has subsequently incorporated
the comments into the latest draft.

(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.

As the protocol describes message security, the Document Shepherd
recommends the document is reviewed by the Security area.

(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 Document Shepherd/Responsible Area Director has not indicated any
specific concerns or issues with 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 authors have confirmed that there are no IPR disclosures required
for full conformance with BCP 78 and BCP 79.

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

There are no IPR disclosures that reference the 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?

The interested community as a whole understands and agrees with the
document, proven by implementation.

(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.

There are no error and no warnings from a verbose nits check of
draft-04. There are comments related to normative references; these
references (AES, CCM and IEEE802154) are correctly stated as normative.

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

No formal review required.

(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?

All normative references are in a clear 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.

There are three documents which the nits checker picked up as possible
downward references:

-- Possible downref: Non-RFC (?) normative reference: ref. 'AES'
-- Possible downref: Non-RFC (?) normative reference: ref. 'CCM'
-- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE802154'

All these are complete standard specifications within their appropriate
standards authority (NIST and IEEE)

(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.

The publication of this document will not affect the status of any
existing RFCs.

(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 considerations section clearly identifies the requirements for MLE:

* Additional UDP service name and port assignment
* Security Suites
* Command Types
* TLV Types
* Network Parameters

(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.

MLE requires a Service Name and Port Number that requires Expert Review.

(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.

There are no parts of the document written in a formal language.

IESG/Authors/ADs:

IANA has reviewed draft-kelsey-intarea-mesh-link-establishment-05. Authors should review the comments and/or questions below. Please report any inaccuracies and respond to any questions as soon as possible.

We received the following comments/questions from the IANA's reviewer:

IANA has questions for some of the IANA actions requested in this
draft document.

IANA understands that, upon approval of this document, there are six actions which must be completed.

First, the following UDP has been assigned to 'mle':

mle 19788 udp Mesh Link Establishment [IESG]

See: http://www.iana.org/assignments/service-names-port-numbers

QUESTION: Should this draft document be cited as the defining
reference in the port number registry?

Second, IANA will create a new top-level registry, called "MLE: Mesh Link Establishment", to contain all MLE objects, codepoints, and sub-registries.

Third, in the newly created MLE: Mesh Link Establishment, a new subregistry will be created called the "Security Suites" subregistry. The registration policy for this new subregistry will be IETF Review as defined in RFC 5226. The values in the new subregistry range from 0 to 255. There are initial values in this registry as follows:

Value Meaning Reference
--------+--------------------------------------+--------------------
0 802.15.4 Security [ RFC-to-be ]
1-254 Unassigned
255 No security [ RFC-to-be ]

Fourth, also in the newly created MLE: Mesh Link Establishment, a new subregistry will be created called the "Command Types" subregistry. The registration policy for this new subregistry will be IETF Review as defined in RFC 5226. The values in the new subregistry range from 0 to 255. There are initial values in this registry as follows:

Value Meaning Reference
--------+---------------------------------------+------------------
0 Link Request [ RFC-to-be ]
1 Link Accept [ RFC-to-be ]
2 Link Accept and Request [ RFC-to-be ]
3 Link Reject [ RFC-to-be ]
4 Advertisement [ RFC-to-be ]
5 Update [ RFC-to-be ]
6 Update Request [ RFC-to-be ]
7-255 Unassigned

QUESTION: Is the value 6 in the following text a typo?

"Values 6-255 are currently unassigned."


Fifth, also in the newly created MLE: Mesh Link Establishment, a new subregistry will be created called the "TLV Types" subregistry. The registration policy for this new subregistry will be IETF Review as defined in RFC 5226. The values in the new subregistry range from 0 to 255. There are initial values in this registry as follows:

Value Meaning Reference
--------+---------------------------------------+------------------
0 Source Address [ RFC-to-be ]
1 Mode [ RFC-to-be ]
2 Timeout [ RFC-to-be ]
3 Challenge [ RFC-to-be ]
4 Response [ RFC-to-be ]
5 Link-layer Frame Counter [ RFC-to-be ]
6 Link Quality [ RFC-to-be ]
7 Network Parameter [ RFC-to-be ]
8 MLE Frame Counter [ RFC-to-be ]
9-255 Unassigned

QUESTION: Is the value 8 in the following text a typo?

Values 8-255 are currently unassigned.

Sixth, also in the newly created MLE: Mesh Link Establishment, a new subregistry will be created called the "Network Parameters" subregistry. The registration policy for this new subregistry will be IETF Review as defined in RFC 5226. The values in the new subregistry range from 0 to 255. There are initial values in this registry as follows:

Value Meaning Reference
--------+---------------------------------------+------------------
0 Channel [ RFC-to-be ]
1 PAN ID [ RFC-to-be ]
2 Permit Joining [ RFC-to-be ]
3 Beacon Payload [ RFC-to-be ]
4-255 Unassigned

IANA understands that these six actions are the only ones required to be completed upon approval of this document.

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
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Mesh Link Establishment) to Proposed Standard


The IESG has received a request from an individual submitter to consider
the following document:
- 'Mesh Link Establishment'
  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 2013-09-16. 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 the mesh link establishment (MLE) protocol for
  establishing and configuring secure radio links in IEEE 802.15.4
  radio mesh networks.  MLE extends IEEE 802.15.4 for use in multihop
  mesh networks by adding three capabilities: 1) dynamically
  configuring and securing radio links, 2) enabling network-wide
  changes to radio parameters, and 3) detecting neighboring devices.
  MLE operates below the routing layer, insulating it from the details
  of configuring, securing, and maintaining individual radio links
  within a larger mesh network.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-kelsey-intarea-mesh-link-establishment/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-kelsey-intarea-mesh-link-establishment/ballot/


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

(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?


i) Type of RFC Requested: Proposed Standard
ii) It is the proper type of RFC because the document describes a
communications protocol
iii) The type of RFC is 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:

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.


MLE is a protocol for link-layer configuration, including link layer
addressing, transmit and receive modes, wake/sleep cycles and security. 
Its use in ad hoc mesh networks is complementary to existing IETF
neighbor discovery protocols, such as IPv6 ND [RFC4861] and NHDP
[RFC6130].  MLE can be used to configure individual links and to
distribute configuration values that are shared across a network. 
Per-link configuration uses one-hop messages with link-local addresses.
Network-wide configuration uses multicasts and requires some form of
multi-hop multicast forwarding.  MLE resolves the issue of determining
two-way link quality between nodes in a lossy network (e.g. wireless) by
allowing a node to periodically multicast an estimate of the quality of
its links.  This allows a node to determine if it has a usable link to a
neighbor without first configuring that link.


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?


Due to the general nature of the protocol and its application to link
layer technology, there was no particular WG which suited the draft. It
has been discussed in the 6lowpan and roll WG mailing lists. The only
controversy notable was the use of UDP as the base protocol for MLE.
Some suggested ICMPv6 would be more appropriate tied to RPL messages,
however this had the criticism of narrowing the scope of MLE, which has
been written without any specific IETF protocol in mind.


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?


There are numerous existing implementations of the protocol as it is
currently being adopted and tested by ZigBee Alliance members involved
in the development of the ZigBee IP stack. There are currently 7
independent vendors implemeting the protocol. Thomas Clausen has
performed a thorough review of draft version 02 and his comments have
been incorporated in version 03 onwards.


Personnel:

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


The Document Shepherd is Robert Cragie. The Responsible Area Director is
Ralph Droms.


(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 and Responsible Area Director have reviewed the
draft document and have been party to the interoperability testing
events undertaken by the vendors to confirm interoperable implementation
of the protocol and its fitness for purpose.


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


The document has been submitted for review on all relevant WG mailing
lists and has had discussion. It has also been through practical
implementations subject to continuous review by the implementors, who
have fed back comments to the author, who has subsequently incorporated
the comments into the latest draft.


(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.


As the protocol describes message security, the Document Shepherd
recommends the document is reviewed by the Security area.


(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 Document Shepherd/Responsible Area Director has not indiciated any
specific concerns or issues with 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 authors have confirmed that there are no IPR disclosures required
for full conformance with BCP 78 and BCP 79.


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


There are no IPR disclosures that reference the 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?


The interested community as a whole understands and agrees with the
document, proven by implementation.


(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.


There are no error and no warnings from a verbose nits check of
draft-04. There are comments related to normative references; these
references (AES, CCM and IEEE802154) are correctly stated as normative.


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


No formal review required.


(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?


All normative references are in a clear 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.


There are three documents which the nits checker picked up as possible
downward references:

-- Possible downref: Non-RFC (?) normative reference: ref. 'AES'
-- Possible downref: Non-RFC (?) normative reference: ref. 'CCM'
-- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE802154'

All these are complete standard specifications within their appropriate
standards authority (NIST and IEEE)


(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.


The publication of this document will not affect the status of any
existing RFCs.


(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 considerations section clearly identifies the requirements for MLE:

* Additional UDP service name and port assignment
* Security Suites
* Command Types
* TLV Types
* Network Parameters


(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.


MLE requires a Service Name and Port Number that requires Expert Review.


(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.


There are no parts of the document written in a formal language.