6LoWPAN Paging Dispatch
draft-ietf-6lo-paging-dispatch-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8025.
|
|
|---|---|---|---|
| Author | Pascal Thubert | ||
| Last updated | 2016-01-14 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 8025 (Proposed Standard) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-6lo-paging-dispatch-00
6lo P. Thubert, Ed.
Internet-Draft Cisco
Updates: 4944 (if approved) January 14, 2016
Intended status: Standards Track
Expires: July 17, 2016
6LoWPAN Paging Dispatch
draft-ietf-6lo-paging-dispatch-00
Abstract
This specification introduces a new context switch mechanism for
6LoWPAN compression, expressed in terms of Pages and signaled by a
new Paging Dispatch.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 17, 2016.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Updating RFC 4944 . . . . . . . . . . . . . . . . . . . . . . 3
4. Page 1 Paging Dispatch . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, a very constrained resource in most cases.
The other constraints, such as the memory capacity and the duty
cycling of the LLN devices, derive from that primary concern. Energy
is often available from primary batteries that are expected to last
for years, or is scavenged from the environment in very limited
quantities. Any protocol that is intended for use in LLNs must be
designed with the primary concern of saving energy as a strict
requirement.
Controlling the amount of data transmission is one possible venue to
save 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 [IEEE802154] is limited to 127
bytes per frame. The need to compress IPv6 packets over IEEE
802.15.4 led to the 6LoWPAN Header Compression [RFC6282] work
(6LoWPAN-HC).
As more and more protocols need to be compressed, the encoding
capabilities of the original dispatch defined in the 6lo adaptation
layer framework ([RFC4944],[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.
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].
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The Terminology used in this document is consistent with and
incorporates that described in `Terminology in Low power And Lossy
Networks' [RFC7102] and [RFC7228].
3. Updating RFC 4944
This draft adapts 6LoWPAN while maintaining backward compatibility
with IPv6 over IEEE 802.15.4 [RFC4944] by introducing a concept of
"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 1111xxxx 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.
Note: This specification does not use the Escape Dispatch, which
extends Page 0 to more values, but rather allocates another Dispatch
Bit Pattern (1111xxxx) 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 is said to be active once the Page N Paging
Dispatch is parsed, and as long as no other Paging Dispatch is
parsed.
The Dispatch bits defined in Page 0 by [RFC4944] are free to be
reused in Pages 1 to 15.
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4. Page 1 Paging Dispatch
This specification defines some special properties for Page 1,
detailed below:
The Dispatch bits defined in Page 0 for 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 back from Page 1 to Page 0 to address LOWPAN_IPHC
and LOWPAN_NHC.
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.
It results that there is no need so far for restoring the Page 0
parsing context after a context was switched to Page 1, so the
value for the Page 0 Paging Dispatch of 11110000 may not actually
be seen in packets following the 6LoWPAN specifications that are
available at the time of writing.
5. Security Considerations
The security considerations of [RFC4944] and [RFC6282] apply.
6. IANA Considerations
This document creates a IANA registry for the 6LoWPAN Routing Header
Type, and assigns the following values:
0..4 : RH3-6LoRH [RFCthis]
5 : RPI-6LoRH [RFCthis]
6 : IPinIP-6LoRH [RFCthis]
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7. Acknowledgments
The authors wish to thank Thomas Watteyne, Tengfei Chang, Martin
Turon, James Woodyatt, Samita Chakrabarti, Jonathan Hui, Gabriel
Montenegro and Ralph Droms for constructive reviews to the design in
the 6lo Working Group.
8. References
8.1. Normative References
[IEEE802154]
IEEE standard for Information Technology, "IEEE std.
802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
and Physical Layer (PHY) Specifications for Low-Rate
Wireless Personal Area Networks", 2015.
[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>.
[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>.
8.2. 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>.
Author's Address
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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
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