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+Internet Engineering Task Force (IETF) P. Thubert, Ed.
+Request for Comments: 8025 Cisco
+Updates: 4944 R. Cragie
+Category: Standards Track ARM
+ISSN: 2070-1721 November 2016
+
+
+ IPv6 over Low-Power Wireless Personal Area
+ Network (6LoWPAN) Paging Dispatch
+
+Abstract
+
+ This specification updates RFC 4944 to introduce a new context switch
+ mechanism for IPv6 over Low-Power Wireless Personal Area Network
+ (6LoWPAN) compression, expressed in terms of Pages and signaled by a
+ new Paging Dispatch.
+
+Status of This Memo
+
+ This is an Internet Standards Track document.
+
+ 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). Further information on
+ Internet Standards is available in 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/rfc8025.
+
+Copyright Notice
+
+ Copyright (c) 2016 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.
+
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 1]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
+ 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 3. Updating RFC 4944 . . . . . . . . . . . . . . . . . . . . . . 3
+ 4. Page 1 Paging Dispatch . . . . . . . . . . . . . . . . . . . 4
+ 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
+ 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
+ 6.1. Page Switch Dispatch Types . . . . . . . . . . . . . . . 5
+ 6.2. New Column in Dispatch Type Registry . . . . . . . . . . 5
+ 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
+ 7.1. Normative References . . . . . . . . . . . . . . . . . . 7
+ 7.2. Informative References . . . . . . . . . . . . . . . . . 7
+ Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
+ Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
+
+1. Introduction
+
+ The design of Low-Power and Lossy Networks (LLNs) is generally
+ focused on saving energy, which is often a very constrained resource.
+ Other constraints, such as memory capacity and duty cycle
+ restrictions on LLN devices, usually derive from that primary
+ concern. Energy is often available only from primary batteries that
+ are expected to last for years or is scavenged from the environment
+ in very limited amounts. Any protocol that is intended for use in
+ LLNs must be designed with a primary focus on saving energy, which is
+ a strict requirement.
+
+ Controlling the amount of data transmission is one possible means of
+ saving energy. In a number of LLN standards, the frame size is
+ limited to much smaller values than the IPv6 maximum transmission
+ unit (MTU) of 1280 bytes. In particular, an LLN that relies on the
+ classical Physical Layer (PHY) of IEEE 802.15.4 [IEEE.802.15.4] is
+ limited to 127 bytes per frame. The need to compress IPv6 packets
+ over IEEE 802.15.4 led to the 6LoWPAN Header Compression (6LoWPAN-HC)
+ [RFC6282] work.
+
+ As more and more protocols need to be compressed, the encoding
+ capabilities of the original dispatch defined in the 6LowPAN
+ adaptation-layer framework ([RFC4944] and [RFC6282]) becomes
+ saturated. This specification introduces a new context switch
+ mechanism for 6LoWPAN compression, expressed in terms of Pages and
+ signaled by a new Paging Dispatch mechanism.
+
+
+
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 2]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+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
+ [RFC2119].
+
+ The terminology used in this document is consistent with and
+ incorporates that described in "Terms Used in Routing for Low-Power
+ and Lossy Networks" [RFC7102] and "Terminology for Constrained-Node
+ Networks" [RFC7228].
+
+3. Updating RFC 4944
+
+ This document adapts 6LoWPAN while maintaining backward compatibility
+ with IPv6 over IEEE 802.15.4 [RFC4944] by introducing the concept of
+ a "parsing context" in the 6LoWPAN parser, a context being identified
+ by a Page Number. This specification defines 16 Pages.
+
+ Pages are delimited in a 6LoWPAN packet by a Paging Dispatch value
+ that indicates the next current Page. The Page Number is encoded in
+ a Paging Dispatch with the Value Bit Pattern of 11 11xxxx, where xxxx
+ is the Page Number, 0 to 15, as described in Figure 1:
+
+ 0
+ 0 1 2 3 4 5 6 7
+ +-+-+-+-+-+-+-+-+
+ |1|1|1|1|Page Nb|
+ +-+-+-+-+-+-+-+-+
+
+ Figure 1: Paging Dispatch with Page Number Encoding
+
+ Values of the Dispatch byte defined in [RFC4944] are considered as
+ belonging to the Page 0 parsing context, which is the default and
+ does not need to be signaled explicitly at the beginning of a 6LoWPAN
+ packet. This ensures backward compatibility with existing
+ implementations of 6LoWPAN.
+
+ The Dispatch bits defined in [RFC4944] are used in Page 0 and are
+ free to be reused in Pages 1 to 15. In Section 4, this specification
+ allocates some values in Page 1 and leaves the rest open for future
+ allocations.
+
+ Values made available by this specification in Pages 1 to 14 are to
+ be assigned for new protocols whereas Page 15 is reserved for
+ Experimental Use [RFC5226].
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 3]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+ Note: This specification does not use the Escape Dispatch, which
+ extends Page 0 to more values, but rather allocates another Dispatch
+ Bit Pattern (11 11xxxx) for a new Paging Dispatch that is present in
+ all Pages, including Page 0 and Pages defined in future
+ specifications, to indicate the next parsing context represented by
+ its Page Number. The rationale for avoiding that approach is that
+ there can be multiple occurrences of a new header indexed by this
+ specification in a single frame and the overhead on an octet each
+ time for the Escape Dispatch would be prohibitive.
+
+ A Page (say Page N) is said to be active once the Page N Paging
+ Dispatch is parsed, and it remains active until another Paging
+ Dispatch is parsed.
+
+4. Page 1 Paging Dispatch
+
+ This specification defines some special properties for Page 1,
+ detailed below:
+
+ The Dispatch bits defined for LOWPAN_IPHC by the "Compression
+ Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks"
+ [RFC6282] are defined with the same values in Page 1, so there is
+ no need to switch context from Page 1 to Page 0 to decode a packet
+ that is encoded per [RFC6282].
+
+ Mesh Headers represent Layer 2 information and are processed
+ before any Layer 3 information that is encoded in Page 1. If a
+ 6LoWPAN packet requires a Mesh Header, the Mesh Header MUST always
+ be placed in the packet before the first Page 1 Paging Dispatch,
+ if any.
+
+ For the same reason, Fragment Headers as defined in [RFC4944] MUST
+ always be placed in the packet before the first Page 1 Paging
+ Dispatch, if any.
+
+ The NALP Dispatch Bit Pattern as defined in [RFC4944] is only
+ defined for the first octet in the packet. Switching back to Page
+ 0 for NALP inside a 6LoWPAN packet does not make sense.
+
+ As a result, there is no need to restore the Page 0 parsing
+ context after a context was switched to Page 1, so the value for
+ the Page 0 Paging Dispatch of 11 110000 may not actually occur in
+ those packets that adhere to 6LoWPAN specifications available at
+ the time of writing this specification.
+
+
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 4]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+5. Security Considerations
+
+ The security considerations of [RFC4944] and [RFC6282] apply.
+
+6. IANA Considerations
+
+6.1. Page Switch Dispatch Types
+
+ This document allocates 16 values for "Page switch" from the
+ "Dispatch Type Field" registry that was created by [RFC4944]. The
+ allocated values are from 11 110000 through 11 111111 and represent
+ Page Numbers 0 through 15 as discussed in this document.
+
+6.2. New Column in Dispatch Type Registry
+
+ This document extends the "Dispatch Type Field" registry, which was
+ created by [RFC4944] and updated by [RFC6282], by adding a new column
+ called "Page".
+
+ This document defines 16 Pages, "Page 0" to "Page 15".
+
+ The preexisting registry content is assigned to "Page 0".
+
+ This document also associates the Dispatch type field values that are
+ allocated for LOWPAN_IPHC by [RFC6282] to Page 1. These values range
+ from 01 100000 through 01 111111 and have the same definition in Page
+ 1 as they do in Page 0; as a result, Page 0 and Page 1 are grouped
+ together in the registry for this range.
+
+ Values ranging from 00 000000 to 11 101111 in Page 15 (that is, all
+ of Page 15 except the space used for Page switch) are reserved for
+ Experimental Use [RFC5226] and shall not be assigned.
+
+ Figure 2 represents the updates to the registry as described above.
+ Refer to <http://www.iana.org/assignments/_6lowpan-parameters> for
+ the complete list of updates.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 5]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Bit Pattern | Page | Header Type | Reference |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | | 0 | NALP | RFC 4944, |
+ | | | | this document |
+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 00 xxxxxx | 1-14 | Unassigned | |
+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
+ | | 15 | Reserved for | this document |
+ | | | Experimental Use | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | | 0 | ESC | RFC 6282, |
+ | | | | this document |
+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 01 000000 | 1-14 | Unassigned | |
+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
+ | | 15 | Reserved for | this document |
+ | | | Experimental Use | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ ... ...
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | | 0-1 | LOWPAN_IPHC | RFC 6282, |
+ | | | | this document |
+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 01 1xxxxx | 2-14 | Unassigned | |
+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
+ | | 15 | Reserved for | this document |
+ | | | Experimental Use | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ ... ...
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 11 11xxxx | 0-15 | Page switch | this document |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 2: Integrating the New Page Column
+
+ Future assignments in these registries are to be coordinated via IANA
+ under the policy of "Specification Required" [RFC5226]. It is
+ expected that this policy will allow for other (non-IETF)
+ organizations to more easily obtain assignments.
+
+
+
+
+
+
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 6]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+7. References
+
+7.1. Normative References
+
+ [IEEE.802.15.4]
+ IEEE, "IEEE Standard for Low-Rate Wireless Networks",
+ IEEE 802.15.4-2015, DOI 10.1109/IEEESTD.2016.7460875,
+ <http://ieeexplore.ieee.org/document/7460875/>.
+
+ [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>.
+
+ [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>.
+
+ [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
+ Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
+ DOI 10.17487/RFC6282, September 2011,
+ <http://www.rfc-editor.org/info/rfc6282>.
+
+7.2. Informative References
+
+ [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
+ Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
+ 2014, <http://www.rfc-editor.org/info/rfc7102>.
+
+ [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
+ Constrained-Node Networks", RFC 7228,
+ DOI 10.17487/RFC7228, May 2014,
+ <http://www.rfc-editor.org/info/rfc7228>.
+
+
+
+
+
+
+
+
+
+
+
+
+Thubert & Cragie Standards Track [Page 7]
+
+RFC 8025 6LoWPAN Paging Dispatch November 2016
+
+
+Acknowledgments
+
+ The authors wish to thank Tom Phinney, Thomas Watteyne, Tengfei
+ Chang, Martin Turon, James Woodyatt, Samita Chakrabarti, Jonathan
+ Hui, Gabriel Montenegro, and Ralph Droms for constructive reviews of
+ the design in the 6lo working group.
+
+Authors' Addresses
+
+ Pascal Thubert (editor)
+ Cisco Systems
+ Building D - Regus
+ 45 Allee des Ormes
+ BP1200
+ Mougins - Sophia Antipolis 06254
+ France
+
+ Phone: +33 4 97 23 26 34
+ Email: pthubert@cisco.com
+
+
+ Robert Cragie
+ ARM Ltd.
+ 110 Fulbourn Road
+ Cambridge CB1 9NJ
+ United Kingdom
+
+ Email: robert.cragie@gridmerge.com
+
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+Thubert & Cragie Standards Track [Page 8]
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