Internet DRAFT - draft-gomez-6lo-schc-dispatch
draft-gomez-6lo-schc-dispatch
6lo Working Group C. Gomez
Internet-Draft UPC
Intended status: Standards Track September 21, 2020
Expires: March 25, 2021
IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) Dispatch
Type for SCHC
draft-gomez-6lo-schc-dispatch-01
Abstract
A new framework called Static Context Header Compression (SCHC) has
been designed with the primary goal of supporting IPv6 over Low Power
Wide Area Network (LPWAN) technologies [RFC8724]. One of the SCHC
components is a header compression mechanism. If used properly, SCHC
header compression allows a greater compression ratio than that
achievable with traditional 6LoWPAN header compression [RFC6282].
For this reason, it may make sense to use SCHC header compression in
some 6LoWPAN environments. This document defines a 6LoWPAN Dispatch
Type to signal when a packet header has been compressed by using SCHC
header compression.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Frame Format . . . . . . . . . . . . . . . . . . . . . . . . 3
4. SCHC Dispatch Type . . . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
RFC 6282 is the main specification for IPv6 over Low power Wireless
Personal Area Network (6LoWPAN) IPv6 header compression [RFC6282].
This RFC was designed assuming IEEE 802.15.4 as the layer below the
6LoWPAN adaptation layer, and it has also been reused (with proper
adaptations) for IPv6 header compression over many other technologies
relatively similar to IEEE 802.15.4 in terms of characteristics such
as physical layer bit rate, layer 2 maximum payload size, etc.
Examples of such technologies comprise BLE, DECT-ULE, ITU G.9959, MS/
TP, NFC, and PLC. RFC 6282 provides additional functionality, such
as a mechanism for UDP header compression.
In the best cases, RFC 6282 allows to compress a 40-byte IPv6 header
down to a 2-byte compressed header (for link-local interactions) or a
3-byte compressed header (when global IPv6 addresses are used). On
the other hand, an RFC 6282 compressed UDP header has a typical size
of 4 bytes. Therefore, in advantageous conditions, a 48-byte
uncompressed IPv6/UDP header may be compressed down to a 6-byte
format (when using link-local addresses) or a 7-byte format (for
global interactions) by using RFC 6282.
Recently, a new framework called Static Context Header Compression
(SCHC) has been designed with the primary goal of supporting IPv6
over Low Power Wide Area Network (LPWAN) technologies [RFC8724].
SCHC comprises header compression and fragmentation functionality
tailored to the extraordinary constraints of LPWAN technologies,
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which are more severe than those exhibited by IEEE 802.15.4 or other
relatively similar technologies.
SCHC header compression allows a greater compression ratio than that
of RFC 6282. If used properly, SCHC allows to compress an IPv6/UDP
header down to e.g. a single byte. Therefore, it may make sense to
use SCHC header compression in some 6LoWPAN environments [I-
D.toutain-6lo-6lo-and-schc], considering its greater efficiency.
If SCHC header compression is added to the panoply of header
compression mechanisms used in 6LoWPAN environments, then there is a
need to signal when a packet header has been compressed by using
SCHC. To this end, in its current form, the present document
specifies a 6LoWPAN Dispatch Type for SCHC header compression, based
on exploiting RFC 8025 Dispatch type space [RFC8025].
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Frame Format
Figure 1 illustrates the content of an encapsulated, SCHC compressed,
IPv6 datagram:
+---------------+-------------+---------+
| SCHC Dispatch | SCHC Header | Payload |
+---------------+-------------+---------+
Figure 1: Encapsulated, SCHC compressed IPv6 datagram
The SCHC Dispatch is a 6LoWPAN Dispatch Type that indicates that the
next field is a SCHC Header. The latter corresponds to a packet
header that has been compressed by using SCHC. As defined in
[RFC8724], the SCHC Header comprises a Rule ID, and a compression
residue. (Note: more details, including a discussion on padding, to
be added.)
4. SCHC Dispatch Type
This section defines the 6LoWPAN Dispatch Type called "SCHC
Dispatch", by using the RFC 8025 concept of "pages". With the aim to
minimize overhead, the present document allocates a whole page (Page
2) for the SCHC Dispatch Type:
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SCHC Dispatch Type bit pattern: 11110010 (Page 2 (Note: to be
confirmed by IANA))
For example, two bytes may be used for the SCHC Dispatch plus the
Rule ID, which offers a Rule ID space of 256 possible Rule IDs.
5. IANA Considerations
This document requests the allocation of the Dispatch Type Field bit
pattern 11110010 (Page 2) as SCHC Dispatch Type.
6. Security Considerations
TBD
7. Acknowledgments
Ana Minaburo and Laurent Toutain suggested for the first time the use
of SCHC in environments where 6LoWPAN has traditionally been used.
Laurent Toutain made comments that helped shape this document.
Carles Gomez has been funded in part by the Spanish Government
through project PID2019-106808RA-I00, and by Secretaria
d'Universitats i Recerca del Departament d'Empresa i Coneixement de
la Generalitat de Catalunya 2017 through grant SGR 376.
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,
<https://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,
<https://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,
<https://www.rfc-editor.org/info/rfc6282>.
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[RFC8025] Thubert, P., Ed. and R. Cragie, "IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Paging Dispatch",
RFC 8025, DOI 10.17487/RFC8025, November 2016,
<https://www.rfc-editor.org/info/rfc8025>.
[RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
Zuniga, "SCHC: Generic Framework for Static Context Header
Compression and Fragmentation", RFC 8724,
DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/info/rfc8724>.
8.2. Informative References
[I-D.toutain-6lo-6lo-and-schc]
Minaburo, A. and L. Toutain, "Comparison of 6lo and SCHC",
draft-toutain-6lo-6lo-and-schc-00 (work in progress),
November 2019.
Author's Address
Carles Gomez
UPC
C/Esteve Terradas, 7
Castelldefels 08860
Spain
Email: carlesgo@entel.upc.edu
Gomez Expires March 25, 2021 [Page 5]
