Internet Engineering Task Force (IETF) T. Kivinen

Internet Engineering Task Force (IETF) T. Kivinen
Request for Comments: 8137 INSIDE Secure
Category: Informational P. Kinney
ISSN: 2070-1721 Kinney Consulting LLC
May 2017

IEEE 802.15.4 Information Element for the IETF

Abstract

IEEE Std 802.15.4 defines Information Elements (IEs) that can be used
to extend 802.15.4 in an interoperable manner. The IEEE 802.15
Assigned Numbers Authority (ANA) manages the registry of the
Information Elements. This document formulates a request for ANA to
allocate a number from that registry for the IETF and describes how
the IE is formatted to provide subtypes.

Status of This Memo

This document is not an Internet Standards Track specification; it is
published for informational purposes.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8137.

Copyright Notice

Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Working Groups Benefiting from the IETF 802.15.4 IE . . . . . 3
4. IETF IE Subtype Format . . . . . . . . . . . . . . . . . . . 3
5. Request to Allocate an IETF IE . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Vendor Specific IE in IEEE 802.15.4 . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7

1. Introduction

IEEE Std 802.15.4 [IEEE802.15.4] is a standard, referred to by RFC
4944 [RFC4944] and other documents, that enables very low-cost and
low-power communications. The standard defines numerous optional
Physical Layers (PHYs) operating in many different frequency bands
with a simple and effective Medium Access Control (MAC).

IEEE Std 802.15.4 defines Information Elements (IEs) that can be used
to extend 802.15.4 in an interoperable manner. An IE provides a
flexible, extensible, and easily implementable method of
encapsulating information. The general format of an IE as defined in
Section 7.4 of IEEE Std 802.15.4-2015 [IEEE802.15.4] consists of an
identification (ID) field, a length field, and a content field.
Multiple IEs may be concatenated, and elements with unknown ID values
in a list of IEs can be skipped since their length is known. IEs
provide a flexible container for information that allows the addition
of new IE definitions in future versions of the standard in a
backwards-compatible manner.

There are two different IE types, Header IE and Payload IE. A Header
IE is part of the MAC header; it is never encrypted, but it may be
authenticated. Most of the Header IE processing is done by the MAC,
and IETF protocols should not have any direct effect on that
processing. A Payload IE is part of the MAC payload and may be
encrypted and authenticated.

IETF protocols will need to insert information in the 802.15.4
frames; the 802.15.4 standard enables that by including one or more
payload IEs in the frame that will contain the information. For this
purpose, the IETF requests a dedicated Payload IE from the IEEE
802.15 Assigned Numbers Authority (ANA) [IEEE802.15-ANA]. The
current 802.15 ANA database can be found at [IEEE802.15-ANA-DB].

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The 802.15.4 operations manual [IEEE802.15-OPS] describes how a
Standards Development Organization (SDO) may request an allocation of
one IE. To make this request the SDO has to provide (i) the reason
for the request, (ii) a description of the protocol format that shows
an appropriate subtype capability, and (iii) an agreement that only
one IE number will be allocated for use by the SDO.

This document provides the information needed for the request.

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
"MAY", and "OPTIONAL" in this document are to be interpreted as
described in BCP 14 [RFC2119] [RFC8174] when, and only when, they
appear in all capitals, as shown here.

3. Working Groups Benefiting from the IETF 802.15.4 IE

There are several IETF working groups such as 6TiSCH, 6lo, and CoRE
that could benefit from the IETF IE. The 6TiSCH Working Group has
already expressed the need for the IE; this allocation is expected to
satisfy that need.

4. IETF IE Subtype Format

The maximum length of the Payload IE content is 2047 octets, and the
802.15.4 frame contains a list of payload IEs. A single frame can
have multiple payload IEs, terminated with the payload IE terminator,
which may then be followed by the payload.

Since the 802.15.4 standard defines a list of payload IEs along with
their structures, there is no need for this document to specify the
internal nesting structure of the IETF IE. The Payload IE format of
802.15.4 standard contains the Length field. The length of the
subtype content can be calculated from the 802.15.4 Payload IE Length
field of the IETF IE.

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The format of the IETF IE is as follows:

1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype ID | |
+-+-+-+-+-+-+-+-+ |
~ subtype content ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: IETF IE Subtype Format

o Subtype ID is the IANA-allocated number specifying the subtype of
the IETF IE. Value 0 is reserved for future extensibility, i.e.,
in case a longer subtype ID field is needed.

o Subtype content is the actual content of the Information Element,
and its length can be calculated from the Length field of the IETF
IE.

One IEEE 802.15.4 frame MAY contain multiple IETF IEs with the same
or different subtypes.

5. Request to Allocate an IETF IE

Per the IETF's request, the IEEE 802.15 Working Group has allocated
an ID (5) for a Payload IE for IETF use. The IETF understands that
this is the only ID it will be issued.

6. Security Considerations

This document creates an IANA registry for IETF IE subtype IDs (see
Section 7). The security of the protocols using the IEs MUST be
described in the documents requesting allocations from this registry.

The IEEE Std 802.15.4 [IEEE802.15.4] contains methods in which
security of the IE can be enforced when a frame is received, but this
is only per IE type. Therefore, all IETF IEs will have the same
security-level requirements regardless of the subtype ID used. This
can cause issues if different security processing would be needed and
any of those IEs would need to be processed in the MAC level. Since
all IETF protocols should operate at a higher level than the MAC
level, the higher-layer processing for these IEs SHOULD perform
separate security policy checking based on the IETF IE subtype ID in
addition to the checks done by the MAC.

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7. IANA Considerations

The "IEEE Std 802.15.4 IETF IE Subtype IDs" registry has been created
as follows:

Value Subtype ID
0 Reserved
1-200 Unassigned
201-255 Experimental Use

Any change or addition to this registry requires Expert Review
[RFC5226].

Note that there are vendor-specific IEs already defined in IEEE
802.15.4 (see Appendix A); because of this, there is no need to
reserve any subtype IDs for the vendor-specific uses.

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8. References

8.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <http://www.rfc-editor.org/info/rfc8174>.

8.2. Informative References

[IEEE802.15.4]
IEEE, "IEEE Standard for Low-Rate Wireless Networks",
IEEE Standard 802.15.4,
<https://standards.ieee.org/about/get/802/802.15.html>.

[IEEE802.15-ANA]
IEEE 802.15, "IEEE 802.15 Assigned Numbers Authority",
<http://www.ieee802.org/15/ANA.html>.

[IEEE802.15-ANA-DB]
IEEE, "IEEE 802.15 ANA database",
<https://mentor.ieee.org/802.15/
documents?is_dcn=257&is_group=0000>.

[IEEE802.15-OPS]
IEEE, "IEEE 802.15 Operations Manual",
<https://mentor.ieee.org/802.15/
documents?is_dcn=235&is_group=0000>.

[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<http://www.rfc-editor.org/info/rfc4944>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.

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Appendix A. Vendor Specific IE in IEEE 802.15.4

IEEE 802.15.4 already has several numbers for different Vendor
Specific IE types. There is one for the Vendor Specific Header IE
for Header IEs. There is one incorrectly named Vendor Specific

Nested IE for Payload IEs, and there is another one with exactly the
same name, but under the MLME Nested IE long format. All of the
Vendor Specific IEs start with a 3-octet vendor OUI to identify the
organization.

Authors' Addresses

Tero Kivinen
INSIDE Secure
Lonnrotinkatu 11
Helsinki FI-00120
Finland

Email: [email protected]

Pat Kinney
Kinney Consulting LLC

Email: [email protected]

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