draft-ietf-6lo-routing-dispatch-00.txt   draft-ietf-6lo-routing-dispatch-01.txt 
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Updates: 4944 (if approved) C. Bormann Updates: 4944 (if approved) C. Bormann
Intended status: Standards Track Uni Bremen TZI Intended status: Standards Track Uni Bremen TZI
Expires: June 6, 2016 L. Toutain Expires: July 15, 2016 L. Toutain
IMT-TELECOM Bretagne IMT-TELECOM Bretagne
R. Cragie R. Cragie
ARM ARM
December 4, 2015 January 12, 2016
6LoWPAN Routing Header And Paging Dispatches 6LoWPAN Routing Header And Paging Dispatches
draft-ietf-6lo-routing-dispatch-00 draft-ietf-6lo-routing-dispatch-01
Abstract Abstract
This specification introduces a new context switch mechanism for This specification introduces a new context switch mechanism for
6LoWPAN compression, expressed in terms of Pages and signaled by a 6LoWPAN compression, expressed in terms of Pages and signaled by a
new Paging Dispatch. A new 6LoWPAN dispatch type is proposed in a new Paging Dispatch. A new 6LoWPAN dispatch type is proposed in a
new Page 1 for use in 6LoWPAN Route-Over topologies, that initially new Page 1 for use in 6LoWPAN Route-Over topologies, that initially
covers the needs of RPL (RFC6550) data packets compression. This covers the needs of RPL (RFC6550) data packets compression. This
specification defines a method to compress RPL Option (RFC6553) specification defines a method to compress RPL Option (RFC6553)
information and Routing Header type 3 (RFC6554), an efficient IP-in- information and Routing Header type 3 (RFC6554), an efficient IP-in-
skipping to change at page 1, line -252 skipping to change at page 1, line -279
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This Internet-Draft will expire on June 6, 2016. This Internet-Draft will expire on July 15, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Updating RFC 4944 . . . . . . . . . . . . . . . . . . . . . . 5 3. Updating RFC 4944 . . . . . . . . . . . . . . . . . . . . . . 6
3.1. New Page 1 Paging Dispatch {#Page 1} . . . . . . . . . . 6 3.1. New Page 1 Paging Dispatch . . . . . . . . . . . . . . . 6
3.2. New Routing Header Dispatch (6LoRH) . . . . . . . . . . . 6 3.2. New Routing Header Dispatch (6LoRH) . . . . . . . . . . . 7
4. Placement Of The New Dispatch Types . . . . . . . . . . . . . 7 4. Placement Of The New Dispatch Types . . . . . . . . . . . . . 7
4.1. Placement Of The Page 1 Paging Dispatch . . . . . . . . . 7 4.1. Placement Of The Page 1 Paging Dispatch . . . . . . . . . 7
4.2. Placement Of The 6LoRH . . . . . . . . . . . . . . . . . 7 4.2. Placement Of The 6LoRH . . . . . . . . . . . . . . . . . 8
5. 6LoWPAN Routing Header General Format . . . . . . . . . . . . 7 5. 6LoWPAN Routing Header General Format . . . . . . . . . . . . 8
5.1. Elective Format . . . . . . . . . . . . . . . . . . . . . 8 5.1. Elective Format . . . . . . . . . . . . . . . . . . . . . 8
5.2. Critical Format . . . . . . . . . . . . . . . . . . . . . 8 5.2. Critical Format . . . . . . . . . . . . . . . . . . . . . 9
6. The Routing Header Type 3 (RH3) 6LoRH . . . . . . . . . . . . 9 6. The Routing Header Type 3 (RH3) 6LoRH . . . . . . . . . . . . 9
7. The RPL Packet Information 6LoRH . . . . . . . . . . . . . . 10 7. The RPL Packet Information 6LoRH . . . . . . . . . . . . . . 11
7.1. Compressing the RPLInstanceID . . . . . . . . . . . . . . 12 7.1. Compressing the RPLInstanceID . . . . . . . . . . . . . . 12
7.2. Compressing the SenderRank . . . . . . . . . . . . . . . 12 7.2. Compressing the SenderRank . . . . . . . . . . . . . . . 13
7.3. The Overall RPI-6LoRH encoding . . . . . . . . . . . . . 12 7.3. The Overall RPI-6LoRH encoding . . . . . . . . . . . . . 13
8. The IP-in-IP 6LoRH . . . . . . . . . . . . . . . . . . . . . 15 8. The IP-in-IP 6LoRH . . . . . . . . . . . . . . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16 9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1. Normative References . . . . . . . . . . . . . . . . . . 17 12.1. Normative References . . . . . . . . . . . . . . . . . . 17
12.2. Informative References . . . . . . . . . . . . . . . . . 18 12.2. Informative References . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
The design of Low Power and Lossy Networks (LLNs) is generally The design of Low Power and Lossy Networks (LLNs) is generally
focused on saving energy, which is the most constrained resource of focused on saving energy, a very constrained resource in most cases.
all. The other constraints, such as the memory capacity and the duty The other constraints, such as the memory capacity and the duty
cycling of the LLN devices, derive from that primary concern. Energy cycling of the LLN devices, derive from that primary concern. Energy
is often available from primary batteries that are expected to last is often available from primary batteries that are expected to last
for years, or is scavenged from the environment in very limited for years, or is scavenged from the environment in very limited
quantities. Any protocol that is intended for use in LLNs must be quantities. Any protocol that is intended for use in LLNs must be
designed with the primary concern of saving energy as a strict designed with the primary concern of saving energy as a strict
requirement. requirement.
Controlling the amount of data transmission is one possible venue to Controlling the amount of data transmission is one possible venue to
save energy. In a number of LLN standards, the frame size is limited save energy. In a number of LLN standards, the frame size is limited
to much smaller values than the IPv6 maximum transmission unit (MTU) to much smaller values than the IPv6 maximum transmission unit (MTU)
of 1280 bytes. In particular, an LLN that relies on the classical of 1280 bytes. In particular, an LLN that relies on the classical
Physical Layer (PHY) of IEEE 802.14.5 [IEEE802154] is limited to 127 Physical Layer (PHY) of IEEE 802.15.4 [IEEE802154] is limited to 127
bytes per frame. The need to compress IPv6 packets over IEEE bytes per frame. The need to compress IPv6 packets over IEEE
802.14.5 led to the 6LoWPAN Header Compression [RFC6282] work 802.15.4 led to the 6LoWPAN Header Compression [RFC6282] work
(6LoWPAN-HC). (6LoWPAN-HC).
Innovative Route-over techniques have been and are still being Innovative Route-over techniques have been and are still being
developed for routing inside a LLN. In a general fashion, such developed for routing inside a LLN. In a general fashion, such
techniques require additional information in the packet to provide techniques require additional information in the packet to provide
loop prevention and to indicate information such as flow loop prevention and to indicate information such as flow
identification, source routing information, etc. identification, source routing information, etc.
For reasons such as security and the capability to send ICMP errors For reasons such as security and the capability to send ICMP errors
back to the source, an original packet must not be tampered with, and back to the source, an original packet must not be tampered with, and
any information that must be inserted in or removed from an IPv6 any information that must be inserted in or removed from an IPv6
packet must be placed in an extra IP-in-IP encapsulation. This is packet must be placed in an extra IP-in-IP encapsulation. This is
the case when the additional routing information is inserted by a the case when the additional routing information is inserted by a
router on the path of a packet, for instance a mesh root, as opposed router on the path of a packet, for instance a mesh root, as opposed
to the source node. This is also the case when some routing to the source node. This is also the case when some routing
information must be removed from a packet that will flow outside the information must be removed from a packet that flows outside the LLN.
LLN. When to use RFC 6553, 6554 and IPv6-in-IPv6
[I-D.robles-roll-useofrplinfo] details different cases where RFC
6553, RFC 6554 and IPv6-in-IPv6 encapsulation is required to set the
bases to help defining the compression of RPL routing information in
LLN environments.
When using [RFC6282] the outter IP header of an IP-in-IP
encapsulation may be compressed down to 2 octets in stateless
compression and down to 3 octets in case of a stateful compression
when a context information must be added.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| 0 | 1 | 1 | TF |NH | HLIM |CID|SAC| SAM | M |DAC| DAM |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Figure 1: LOWPAN_IPHC base Encoding (RFC6282).
The Stateless Compression of an IPv6 addresses can only happen if the
IPv6 address can de deduced from the MAC addresses, meaning that the
IP end point is also the MAC-layer endpoint. This is generally not
the case in a RPL network which is generally a multi-hop route-over
(operated at Layer-3) network. A better compression, that does not
involve variable compressions depending on the hop in the mesh, can
be achieved based on the fact that the outter encapsulation is
usually between the source (or destination) of the inner packet and
the root. Also, the inner IP header can only be compressed by
[RFC6282] if all the fields up to it are also compressed. This
specification makes it so that the inner IP header is the first
header that is compressed by [RFC6282], and conserves the inner
packet encoded the same way whether it is encapsulated or not,
conserving existing implementation.
As an example, the Routing Protocol for Low Power and Lossy Networks As an example, the Routing Protocol for Low Power and Lossy Networks
[RFC6550] (RPL) is designed to optimize the routing operations in [RFC6550] (RPL) is designed to optimize the routing operations in
constrained LLNs. As part of this optimization, RPL requires the constrained LLNs. As part of this optimization, RPL requires the
addition of RPL Packet Information (RPI) in every packet, as defined addition of RPL Packet Information (RPI) in every packet, as defined
in Section 11.2 of [RFC6550]. in Section 11.2 of [RFC6550].
The RPL Option for Carrying RPL Information in Data-Plane Datagrams The RPL Option for Carrying RPL Information in Data-Plane Datagrams
[RFC6553] specification indicates how the RPI can be placed in a RPL [RFC6553] specification indicates how the RPI can be placed in a RPL
Option for use in an IPv6 Hop-by-Hop header. This representation Option for use in an IPv6 Hop-by-Hop header. This representation
skipping to change at page 1, line -140 skipping to change at page 1, line -134
+-----+ | | | IPv6 in +-----+ | | | IPv6 in
| | | | IPv6 | | | | IPv6
o o o o | | | + RPI o o o o | | | + RPI
o o o o o o o o o | | | or RH3 o o o o o o o o o | | | or RH3
o o o o o o o o o o | | | o o o o o o o o o o | | |
o o o o o o o o o | | | o o o o o o o o o | | |
o o o o o o o o v v v o o o o o o o o v v v
o o o o o o o o
LLN LLN
Figure 1: IP-in-IP Encapsulation within the LLN Figure 2: IP-in-IP Encapsulation within the LLN.
Additionally, in the case of the Non-Storing Mode of Operation (MOP), Additionally, in the case of the Non-Storing Mode of Operation (MOP),
RPL requires a Routing Header type 3 (RH3) as defined in the IPv6 RPL requires a Routing Header type 3 (RH3) as defined in the IPv6
Routing Header for Source Routes with RPL [RFC6554] specification, Routing Header for Source Routes with RPL [RFC6554] specification,
for all packets that are routed down a RPL graph. With Non-Storing for all packets that are routed down a RPL graph. With Non-Storing
RPL, even if the source is a node in the same LLN, the packet must RPL, even if the source is a node in the same LLN, the packet must
first reach up the graph to the root so that the root can insert the first reach up the graph to the root so that the root can insert the
RH3 to go down the graph. In any fashion, whether the packet was RH3 to go down the graph. In any fashion, whether the packet was
originated in a node in the LLN or outside the LLN, and regardless of originated in a node in the LLN or outside the LLN, and regardless of
whether the packet stays within the LLN or not, as long as the source whether the packet stays within the LLN or not, as long as the source
of the packet is not the root itself, the source-routing operation of the packet is not the root itself, the source-routing operation
also implies an IP-in-IP encapsulation at the root to insert the RH3. also implies an IP-in-IP encapsulation at the root in order to insert
the RH3.
6TiSCH [I-D.ietf-6tisch-architecture] specifies the operation of IPv6 6TiSCH [I-D.ietf-6tisch-architecture] specifies the operation of IPv6
over the TimeSlotted Channel Hopping [I-D.ietf-6tisch-tsch] (TSCH) over the TimeSlotted Channel Hopping [RFC7554] (TSCH) mode of
mode of operation of IEEE 802.14.5. The architecture requires the operation of IEEE 802.15.4. The architecture requires the use of
use of both RPL and the 6lo adaptation layer framework ([RFC4944], both RPL and the 6lo adaptation layer framework ([RFC4944],
[RFC6282]) over IEEE 802.14.5. Because it inherits the constraints [RFC6282]) over IEEE 802.15.4. Because it inherits the constraints
on the frame size from the MAC layer, 6TiSCH cannot afford to spend 8 on the frame size from the MAC layer, 6TiSCH cannot afford to spend 8
bytes per packet on the RPI. Hence the requirement for a 6LoWPAN bytes per packet on the RPI. Hence the requirement for a 6LoWPAN
header compression of the RPI. header compression of the RPI.
The type of information that needs to be present in a packet inside An extensible compression technique is required that simplifies IP-
the LLN but not outside of the LLN varies with the routing operation, in-IP encapsulation when it is needed, and optimally compresses
but there is overall a need for an extensible compression technique existing routing artifacts found in RPL LLNs.
that would simplify the IP-in-IP encapsulation, when needed, and
optimally compress existing routing artifacts found in LLNs.
This specification extends the 6lo adaptation layer framework so as This specification extends the 6lo adaptation layer framework
to carry routing information for Route-over use cases. The ([RFC4944],[RFC6282]) so as to carry routing information for route-
specification includes the formats necessary for RPL and is over networks based on RPL. The specification includes the formats
extensible for additional formats. necessary for RPL and is extensible for additional formats.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
The Terminology used in this document is consistent with and The Terminology used in this document is consistent with and
incorporates that described in `Terminology in Low power And Lossy incorporates that described in `Terminology in Low power And Lossy
skipping to change at page 1, line -84 skipping to change at page 1, line -79
Other terms in use in LLNs are found in [RFC7228]. Other terms in use in LLNs are found in [RFC7228].
The term "byte" is used in its now customary sense as a synonym for The term "byte" is used in its now customary sense as a synonym for
"octet". "octet".
3. Updating RFC 4944 3. Updating RFC 4944
This draft adapts 6LoWPAN while maintaining backward compatibility This draft adapts 6LoWPAN while maintaining backward compatibility
with IPv6 over IEEE 802.15.4 [RFC4944] by introducing a concept of 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 "context" in the 6LoWPAN parser, a context being identified by a Page
number, and defines 16 Pages. number. This specification defines 16 Pages.
Pages are delimited in a 6LoWPAN packet by a Paging Dispatch value Pages are delimited in a 6LoWPAN packet by a Paging Dispatch value
that indicates the next current Page. The Page number is encoded in that indicates the next current Page. The Page number is encoded in
a Paging Dispatch with the Value Bit Pattern of 1111xxxx where xxxx a Paging Dispatch with the Value Bit Pattern of 1111xxxx where xxxx
is the Page number, 0 to 15, as follows: is the Page number, 0 to 15, as described in Figure 3:
0 0
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|1|1|1|1|Page Nb| |1|1|1|1|Page Nb|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 2: Paging Dispatch with Page Number Encoding Figure 3: Paging Dispatch with Page Number Encoding.
Values of the Dispatch byte defined in [RFC4944] are considered as Values of the Dispatch byte defined in [RFC4944] are considered as
belonging to a Page 0 parsing context, which is the default and does belonging to the Page 0 parsing context, which is the default and
not need to be signaled explicitly at the beginning of a 6LoWPAN does not need to be signaled explicitly at the beginning of a 6LoWPAN
packet. That way, backward compatibility with existing packet. This ensures backward compatibility with existing
implementations in ensured. implementations of 6LoWPAN.
Note: This specification does not use the Escape Dispatch, which Note: This specification does not use the Escape Dispatch, which
extends Page 0 to more values, but rather allocates another Dispatch extends Page 0 to more values, but rather allocates another Dispatch
Bit Pattern (1111xxxx) for a new Paging Dispatch, that is present in Bit Pattern (1111xxxx) for a new Paging Dispatch, that is present in
all Pages, including Page 0 and Pages defined in future all Pages, including Page 0 and Pages defined in future
specifications, to indicate the next parsing context represented by specifications, to indicate the next parsing context represented by
its Page number. its Page number. The rationale for avoiding that approach is that
there will 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.
3.1. New Page 1 Paging Dispatch {#Page 1} 3.1. New Page 1 Paging Dispatch
This draft defines a new Page 1 Paging Dispatch with a Dispatch Value This draft defines a new Page 1 Paging Dispatch (Dispatch Value of
of 11110001 that indicates a context switch in the 6LoWPAN parser to 11110001), which indicates a context switch in the 6LoWPAN parser to
a Page 1. a Page 1.
The Dispatch bits defined in Page 0 by [RFC4944] are free to be The Dispatch bits defined in Page 0 by [RFC4944] are free to be
reused in the next Pages, 1 to 15. reused in Pages 1 to 15.
On the other hand, the Dispatch bits defined in Page 0 for the On the other hand, the Dispatch bits defined in Page 0 for the
Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based
Networks [RFC6282] are defined with the same values in Page 1 so 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 there is no need to switch context back from Page 1 to Page 0 to
address LOWPAN_IPHC and LOWPAN_NHC. address LOWPAN_IPHC and LOWPAN_NHC.
3.2. New Routing Header Dispatch (6LoRH) 3.2. New Routing Header Dispatch (6LoRH)
This specification introduces a new 6LoWPAN Routing Header (6LoRH) to This specification introduces a new 6LoWPAN Routing Header (6LoRH) to
carry IPv6 routing information. The 6LoRH may contain source routing carry IPv6 routing information. The 6LoRH may contain source routing
information such as a compressed form of RH3, as well as other sorts information such as a compressed form of RH3, as well as other sorts
of routing information such as the RPL Packet Information and IP-in- of routing information such as the RPL Packet Information and IP-in-
IP encapsulation. IP encapsulation.
The 6LoRH is expressed in a 6loWPAN packet as a Type-Length-Value The 6LoRH is expressed in a 6loWPAN packet as a Type-Length-Value
(TLV) field, which is extensible for future uses. (TLV) field, which is extensible for future use.
This specification uses the bit pattern 10xxxxxx in Page 1 for the This specification uses the bit pattern 10xxxxxx in Page 1 for the
new 6LoRH Dispatch. new 6LoRH Dispatch and Section 5 describes how RPL artifacts in data
packets can be compressed as 6LoRH headers.
The 6LoRH uses on a 1/4th of the Dispatch space in Page 1, and this
specification only uses a limited portion of the TLV space in the
6LoRH to encode RPL artifacts as detailed in Section 5.
It is expected that in the future, other specification with extend
the 6LoRH for other features related to packet routing and forwarding
in 6LoWPAN networks.
4. Placement Of The New Dispatch Types 4. Placement Of The New Dispatch Types
4.1. Placement Of The Page 1 Paging Dispatch 4.1. Placement Of The Page 1 Paging Dispatch
In a zone of a packet where Page 1 is active, which means once a Page In a zone of a packet where Page 1 is active, which means once a Page
1 Paging Dispatch is parsed, and as long as no other Paging Dispatch 1 Paging Dispatch is parsed, and as long as no other Paging Dispatch
is parsed, the parsing of the packet MUST follow this specification is parsed, the parsing of the packet MUST follow this specification
if the 6LoRH Bit Pattern [Section 5] is found. if the 6LoRH Bit Pattern Section 3.2 is found.
Mesh Headers represent Layer-2 information and are processed before Mesh Headers represent Layer-2 information and are processed before
any Layer-3 information that is encoded in Page 1. If a 6LoWPAN 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 packet requires a Mesh header, the Mesh Header MUST always be placed
in the packet before the first Page 1 Paging Dispatch, if any. in the packet before the first Page 1 Paging Dispatch, if any.
For the same reason, Fragments Headers as defined in [RFC4944] MUST For the same reason, Fragment Headers as defined in [RFC4944] MUST
always be placed in the packet before the first Page 1 Paging always be placed in the packet before the first Page 1 Paging
Dispatch, if any. Dispatch, if any.
It must be noted that the NALP Dispatch Bit Pattern as defined in The NALP Dispatch Bit Pattern as defined in [RFC4944] is only defined
[RFC4944] is only defined for the first octet in the packet. for the first octet in the packet. Switching back to Page 0 for NALP
Switching back to Page 0 for NALP inside a 6LoWPAN packet appears inside a 6LoWPAN packet does not make sense.
non-sensical.
parsing context after a context was switched to Page 1, so the value 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 for the Page 0 Paging Dispatch of 11110000 may not actually be seen
in packets following the 6LoWPAN specifications that are available at in packets following the 6LoWPAN specifications that are available at
the time of this writing. the time of writing.
4.2. Placement Of The 6LoRH 4.2. Placement Of The 6LoRH
With this specification, the 6LoRH [Section 5] is only defined in With this specification, the 6LoRH Dispatch is only defined in Page
context is active. context is active.
One or more 6LoRHs MAY be placed in a 6LoWPAN packet and MUST always One or more 6LoRH header(s) MAY be placed in a 6LoWPAN packet. A
be placed before the LOWPAN_IPHC [RFC6282]. 6LoRH header MUST always be placed before the LOWPAN_IPHC as defined
in 6LoWPAN Header Compression [RFC6282].
A 6LoRH being placed in a Page 1 context, it MUST always be placed A 6LoRH header being always placed in a Page 1 context, it MUST
after any Fragmentation Header and/or Mesh Header [RFC4944], even if always be placed after any Fragmentation Header and/or Mesh Header
a sur-compression mechanism is used that elides the Paging [RFC4944].
Dispatches.
5. 6LoWPAN Routing Header General Format 5. 6LoWPAN Routing Header General Format
In its canonical form, the 6LoRH reuses in Page 1 the Dispatch Value The 6LoRH reuses in Page 1 the Dispatch Value Bit Pattern of
Bit Pattern of 10xxxxxx that is defined in Page 0 for the Mesh Header 10xxxxxx.
in [RFC4944].
The Dispatch Value Bit Pattern is split in two forms of 6LoRH: The Dispatch Value Bit Pattern is split in two forms of 6LoRH:
Elective (6LoRHE) that may skipped if not understood Elective (6LoRHE) that may skipped if not understood
Critical (6LoRHC) that may not be ignored Critical (6LoRHC) that may not be ignored
5.1. Elective Format 5.1. Elective Format
In its canonical form, the 6LoRHE uses the Dispatch Value Bit Pattern The 6LoRHE uses the Dispatch Value Bit Pattern of 101xxxxx. A 6LoRHE
of 101xxxxx. A 6LoRHE may be ignored and skipped in parsing. If it may be ignored and skipped in parsing. If it is ignored, the 6LoRHE
is ignored, the 6LoRHE is forwarded with no change inside the LLN. is forwarded with no change inside the LLN.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
|1|0|1| Length | Type | | |1|0|1| Length | Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
<-- Length --> <-- Length -->
Figure 3: Elective 6LoWPAN Routing Header Figure 4: Elective 6LoWPAN Routing Header.
Length: Length:
Length of the 6LoRHE expressed in bytes, excluding the first 2 Length of the 6LoRHE expressed in bytes, excluding the first 2
bytes. This is done to enable a node to skip a 6LoRH that it does bytes. This enables a node to skip a 6LoRHE header that it does
not support and/or cannot parse, for instance if the Type is not not support and/or cannot parse, for instance if the Type is not
known. known.
Type: Type:
Type of the 6LoRHE Type of the 6LoRHE
5.2. Critical Format 5.2. Critical Format
In its canonical form, the 6LoRHC uses the Dispatch Value Bit Pattern The 6LoRHC uses the Dispatch Value Bit Pattern of 100xxxxx.
of 100xxxxx.
A node which does not support the 6LoRHC Type MUST silently discard A node which does not support the 6LoRHC Type MUST silently discard
the packet. the packet.
Note: there is no provision for the exchange of error messages; such Note: The situation where a node receives a message with a Critical
a situation should be avoided by judicious use of administrative 6LoWPAN Routing Header that it does not understand is a critical
control and/or capability indications. administrative error whereby the wrong device is placed in a network.
It makes no sense to overburden the constrained device with code that
would cause ICMP error to the source. Rather, it is expected that
the device will raise some management alert indicating that it cannot
operate in this network for that reason. It results that there is no
provision for the exchange of error messages for this situation; it
should be avoided by judicious use of administrative control and/or
capability indications by the device manufacturer.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
|1|0|0| TSE | Type | | |1|0|0| TSE | Type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
<-- Length implied by Type/TSE --> <-- Length implied by Type/TSE -->
Figure 4: Critical 6LoWPAN Routing Header Figure 5: Critical 6LoWPAN Routing Header.
TSE: TSE:
Type Specific Extension. The meaning depends on the Type, which Type Specific Extension. The meaning depends on the Type, which
must be known in all of the nodes. The interpretation of the TSE must be known in all of the nodes. The interpretation of the TSE
depends on the Type field that follows. For instance, it may be depends on the Type field that follows. For instance, it may be
used to transport control bits, the number of elements in an used to transport control bits, the number of elements in an
array, or the length of the remainder of the 6LoRHC expressed in a array, or the length of the remainder of the 6LoRHC expressed in a
unit other than bytes. unit other than bytes.
Type: Type:
Type of the 6LoRHC Type of the 6LoRHC
6. The Routing Header Type 3 (RH3) 6LoRH 6. The Routing Header Type 3 (RH3) 6LoRH
The Routing Header type 3 (RH3) 6LoRH (RH3-6LoRH) is a Critical The Routing Header type 3 (RH3) 6LoRH (RH3-6LoRH) is a Critical
6LoWPAN Routing Header that provides a compressed form for the RH3, 6LoWPAN Routing Header that provides a compressed form for the RH3,
as defined in [RFC6554] for use by RPL routers. Routers that need to as defined in [RFC6554] for use by RPL routers. Routers that need to
forward a packet with a RH3-6LoRH are expected to be RPL routers and forward a packet with a RH3-6LoRH are expected to be RPL routers and
expected to support this specification. If a non-RPL router receives are expected to support this specification. If a non-RPL router
a packet with a RPI-6LoRH, this means that there was a routing error receives a packet with a RH3-6LoRH, this means that there was a
and the packet should be dropped so the Type cannot be ignored. routing error and the packet should be dropped so the Type cannot be
ignored.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+
|1|0|0| Size |6LoRH Type 0..4| Hop1 | Hop2 | | HopN | |1|0|0| Size |6LoRH Type 0..4| Hop1 | Hop2 | | HopN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+- -+ ... +- -+
Size indicates the number of compressed addresses Size indicates the number of compressed addresses
Figure 5: The RH3-6LoRH Figure 6: The RH3-6LoRH.
The values for the RH3-6LoRH Type are an enumeration, 0 to 4. The The values for the RH3-6LoRH Type are an enumeration, 0 to 4. The
form of compression is indicated by the Type as follows: form of compression is indicated by the Type. The unit (as a number
of bytes) in which the Size is expressed depends on the Type as
described in Figure 7:
+-----------+-----------+ +-----------+-----------+
| Type | Size Unit | | Type | Size Unit |
+-----------+-----------+ +-----------+-----------+
| 0 | 1 | | 0 | 1 |
| 1 | 2 | | 1 | 2 |
| 2 | 4 | | 2 | 4 |
| 3 | 8 | | 3 | 8 |
| 4 | 16 | | 4 | 16 |
+-----------+-----------+ +-----------+-----------+
Figure 6: The RH3-6LoRH Types Figure 7: The RH3-6LoRH Types.
In the case of a RH3-6LoRH, the TSE field is used as a Size, which In the case of a RH3-6LoRH, the TSE field is used as a Size, which
encodes the number of hops minus 1; so a Size of 0 means one hop, and encodes the number of hops minus 1; so a Size of 0 means one hop, and
the maximum that can be encoded is 32 hops. (If more than 32 hops the maximum that can be encoded is 32 hops. (If more than 32 hops
need to be expressed, a sequence of RH3-6LoRH can be employed.) need to be expressed, a sequence of RH3-6LoRH can be employed.)
The next Hop is indicated in the first entry of the first RH3-6LoRH. The Next Hop is indicated in the first entry of the first RH3-6LoRH.
Upon reception, the entry is checked whether it refers to the Upon reception, the router checks whether it owns the address
processing router itself. If it so, the entry is removed from the indicated as Next Hop, which MUST be the case in a strict source
routing environment. If it is so, the entry is removed from the
RH3-6LoRH and the Size is decremented. If the Size is now zero, the RH3-6LoRH and the Size is decremented. If the Size is now zero, the
whole RH3-6LoRH is removed. If there is no more RH3-6LoRH, the whole RH3-6LoRH is removed. If there is no more RH3-6LoRH, the
processing node is the last router on the way, which may or may not processing node is the last router on the way, which may or may not
be collocated with the final destination. be collocated with the final destination.
The last hop in the last RH3-6LoRH is the last router prior to the The last hop in the last RH3-6LoRH is the last router on the way to
destination in the LLN. So even when there is a RH3-6LoRH in the the destination in the LLN. In a classical RPL network, all nodes
frame, the address of the final destination is in the LoWPAN_IPHC are routers so the last hop is effectively the destination as well.
[RFC6282]. But in the general case, even when there is a RH3-6LoRH header
present, the address of the final destination is always indicated in
the LoWPAN_IPHC [RFC6282].
If some bits of the first address in the RH3-6LoRH can be derived If some bits of the first address in the RH3-6LoRH can be derived
from the final destination is in the LoWPAN_IPHC, then that address from the final destination in the LoWPAN_IPHC, then that address may
may be compressed, otherwise is is expressed in full. Next addresses be compressed, otherwise it is expressed as a full IPv6 address of
only need to express the delta from the previous address. 128 bits. Next addresses only need to express the delta from the
previous address.
All addresses in a RH3-6LoRH are compressed in a same fashion, down All addresses in a given RH3-6LoRH header are compressed in a same
to the same number of bytes per address. In order to get different fashion, down to the same number of bytes per address. In order to
forms of compression, multiple consecutive RH3-6LoRH must be used. get different forms of compression, multiple consecutive RH3-6LoRH
must be used.
7. The RPL Packet Information 6LoRH 7. The RPL Packet Information 6LoRH
[RFC6550], Section 11.2, specifies the RPL Packet Information (RPI) [RFC6550], Section 11.2, specifies the RPL Packet Information (RPI)
as a set of fields that are to be added to the IP packets for the as a set of fields that are placed by RPL routers in IP packets for
purpose of Instance Identification, as well as Loop Avoidance and the purpose of Instance Identification, as well as Loop Avoidance and
Detection. Detection.
In particular, the SenderRank, which is the scalar metric computed by In particular, the SenderRank, which is the scalar metric computed by
an specialized Objective Function such as [RFC6552], indicates the an specialized Objective Function such as [RFC6552], indicates the
Rank of the sender and is modified at each hop. The SenderRank Rank of the sender and is modified at each hop. The SenderRank field
allows to validate that the packet progresses in the expected is used to validate that the packet progresses in the expected
direction, either upwards or downwards, along the DODAG. direction, either upwards or downwards, along the DODAG.
RPL defines the RPL Option for Carrying RPL Information in Data-Plane RPL defines the RPL Option for Carrying RPL Information in Data-Plane
Datagrams [RFC6553] to transport the RPI, which is carried in an IPv6 Datagrams [RFC6553] to transport the RPI, which is carried in an IPv6
Hop-by-Hop Options Header [RFC2460], typically consuming eight bytes Hop-by-Hop Options Header [RFC2460], typically consuming eight bytes
per packet. per packet.
With [RFC6553], the RPL option is encoded as six Octets; it must be With [RFC6553], the RPL option is encoded as six Octets; it must be
placed in a Hop-by-Hop header that consumes two additional octets for placed in a Hop-by-Hop header that consumes two additional octets for
a total of eight. In order to limit its range to the inside the RPL a total of eight. In order to limit its range to the inside the RPL
domain, the Hop-by-Hop header must be added to (or removed from) domain, the Hop-by-Hop header must be added to (or removed from)
packets that cross the border of the RPL domain. packets that cross the border of the RPL domain.
The 8-bytes overhead is detrimental to the LLN operation, in The 8-byte overhead is detrimental to the LLN operation, in
particular with regards to bandwidth and battery constraints. These particular with regards to bandwidth and battery constraints. These
bytes may cause a containing frame to grow above maximum frame size, bytes may cause a containing frame to grow above maximum frame size,
leading to Layer 2 or 6LoWPAN [RFC4944] fragmentation, which in turn leading to Layer 2 or 6LoWPAN [RFC4944] fragmentation, which in turn
cause even more energy spending and issues discussed in the LLN causes even more energy spending and issues discussed in the LLN
Fragment Forwarding and Recovery Fragment Forwarding and Recovery
[I-D.thubert-6lo-forwarding-fragments]. [I-D.thubert-6lo-forwarding-fragments].
An additional overhead comes from the need, in certain cases, to add An additional overhead comes from the need, in certain cases, to add
an IP-in-IP encapsulation to carry the Hop-by-Hop header. This is an IP-in-IP encapsulation to carry the Hop-by-Hop header. This is
needed when the router that inserts the Hop-by-Hop header is not the needed when the router that inserts the Hop-by-Hop header is not the
source of the packet, so that an error can be returned to the router. source of the packet, so that an error can be returned to the router.
This is also the case when a packet originated by a RPL node must be This is also the case when a packet originated by a RPL node must be
stripped from the Hop-by-Hop header to be routed outside the RPL stripped from the Hop-by-Hop header to be routed outside the RPL
domain. domain.
This specification defines an IPinIP-6LoRH in Section 8 for that This specification defines an IPinIP-6LoRH in Section 8 for that
purpose, but it must be noted that stripping a 6LoRH does not require purpose, but it must be noted that stripping a 6LoRH does not require
a manipulation of the packet in the LOWPAN_IPHC, and thus, if the a manipulation of the packet in the LOWPAN_IPHC, and thus, if the
source address in the LOWPAN_IPHC is the node that inserted the source address in the LOWPAN_IPHC is the node that inserted the
IPinIP-6LoRH then this alone does not mandate an IPinIP-6LoRH. IPinIP-6LoRH then this alone does not mandate an IPinIP-6LoRH.
As a result, a RPL packet may bear only a RPI-6LoRH and no IPinIP- Note: A typical packet in RPL non-storing mode going down the RPL
graph requires an IP-in-IP encapsulating the RH3, whereas the RPI is
usually (and quite illegally) omitted, unless it is important to
indicate the RPLInstanceID. To match this structure, an optimized
IP-in-IP 6LoRH is defined in Section 8.
As a result, a RPL packet may bear only an RPI-6LoRH and no IPinIP-
6LoRH. In that case, the source and destination of the packet are 6LoRH. In that case, the source and destination of the packet are
located in the LOWPAN_IPHC. located in the LOWPAN_IPHC.
As with [RFC6553], the fields in the RPI include an 'O', an 'R', and As with [RFC6553], the fields in the RPI include an 'O', an 'R', and
an 'F' bit, an 8-bit RPLInstanceID (with some internal structure), an 'F' bit, an 8-bit RPLInstanceID (with some internal structure),
and a 16-bit SenderRank. and a 16-bit SenderRank.
The remainder of this section defines the RPI-6LoRH, a Critical The remainder of this section defines the RPI-6LoRH, a Critical
6LoWPAN Routing Header that is designed to transport the RPI in 6LoWPAN Routing Header that is designed to transport the RPI in
6LoWPAN LLNs. 6LoWPAN LLNs.
7.1. Compressing the RPLInstanceID 7.1. Compressing the RPLInstanceID
RPL Instances are discussed in [RFC6550], Section 5. A number of RPL Instances are discussed in [RFC6550], Section 5. A number of
simple use cases will not require more than one instance, and in such simple use cases do not require more than one instance, and in such
a case, the instance is expected to be the global Instance 0. A cases, the instance is expected to be the global Instance 0. A
global RPLInstanceID is encoded in a RPLInstanceID field as follows: global RPLInstanceID is encoded in a RPLInstanceID field as follows:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0| ID | Global RPLInstanceID in 0..127 |0| ID | Global RPLInstanceID in 0..127
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 7: RPLInstanceID Field Format for Global Instances Figure 8: RPLInstanceID Field Format for Global Instances.
For the particular case of the global Instance 0, the RPLInstanceID For the particular case of the global Instance 0, the RPLInstanceID
field is all zeros. This specification allows to elide a field is all zeros. This specification allows to elide a
RPLInstanceID field that is all zeros, and defines a I flag that, RPLInstanceID field that is all zeros, and defines a I flag that,
when set, signals that the field is elided. when set, signals that the field is elided.
7.2. Compressing the SenderRank 7.2. Compressing the SenderRank
The SenderRank is the result of the DAGRank operation on the rank of The SenderRank is the result of the DAGRank operation on the rank of
the sender; here the DAGRank operation is defined in [RFC6550], the sender; here the DAGRank operation is defined in [RFC6550],
skipping to change at page 13, line 26 skipping to change at page 14, line 11
RPLInstanceID is elided and/or the SenderRank is compressed and RPLInstanceID is elided and/or the SenderRank is compressed and
depending on these bits, the Length of the RPI-6LoRH may vary as depending on these bits, the Length of the RPI-6LoRH may vary as
described hereafter. described hereafter.
0 1 2 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+
|1|0|0|O|R|F|I|K| 6LoRH Type=5 | Compressed fields | |1|0|0|O|R|F|I|K| 6LoRH Type=5 | Compressed fields |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... -+-+-+
Figure 8: The Generic RPI-6LoRH Format Figure 9: The Generic RPI-6LoRH Format.
O, R, and F bits: O, R, and F bits:
The O, R, and F bits as defined in [RFC6550], Section 11.2. The O, R, and F bits as defined in [RFC6550], Section 11.2.
I bit: I bit:
If it is set, the Instance ID is elided and the RPLInstanceID If it is set, the Instance ID is elided and the RPLInstanceID
is the Global RPLInstanceID 0. If it is not set, the octet is the Global RPLInstanceID 0. If it is not set, the octet
immediately following the type field contains the RPLInstanceID immediately following the type field contains the RPLInstanceID
as specified in [RFC6550] section 5.1. as specified in [RFC6550] section 5.1.
K bit: K bit:
If it is set, the SenderRank is be compressed into one octet, If it is set, the SenderRank is be compressed into one octet,
and the lowest significant octet is elided. If it is not set, and the lowest significant octet is elided. If it is not set,
the SenderRank, is fully inlined as 2 octets. the SenderRank, is fully inlined as 2 octets.
In Figure 9, the RPLInstanceID is the Global RPLInstanceID 0, and the In Figure 10, the RPLInstanceID is the Global RPLInstanceID 0, and
MinHopRankIncrease is a multiple of 256 so the least significant byte the MinHopRankIncrease is a multiple of 256 so the least significant
is all zeros and can be elided: byte is all zeros and can be elided:
0 1 2 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|0|O|R|F|1|1| 6LoRH Type=5 | SenderRank | |1|0|0|O|R|F|1|1| 6LoRH Type=5 | SenderRank |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
I=1, K=1 I=1, K=1
Figure 9: The most compressed RPI-6LoRH Figure 10: The most compressed RPI-6LoRH.
In Figure 10, the RPLInstanceID is the Global RPLInstanceID 0, but In Figure 11, the RPLInstanceID is the Global RPLInstanceID 0, but
both bytes of the SenderRank are significant so it can not be both bytes of the SenderRank are significant so it can not be
compressed: compressed:
0 1 2 3 0 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|0|O|R|F|1|0| 6LoRH Type=5 | SenderRank | |1|0|0|O|R|F|1|0| 6LoRH Type=5 | SenderRank |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
I=1, K=0 I=1, K=0
Figure 10: Eliding the RPLInstanceID Figure 11: Eliding the RPLInstanceID.
In Figure 11, the RPLInstanceID is not the Global RPLInstanceID 0, In Figure 12, the RPLInstanceID is not the Global RPLInstanceID 0,
and the MinHopRankIncrease is a multiple of 256: and the MinHopRankIncrease is a multiple of 256:
0 1 2 3 0 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|0|O|R|F|0|1| 6LoRH Type=5 | RPLInstanceID | SenderRank | |1|0|0|O|R|F|0|1| 6LoRH Type=5 | RPLInstanceID | SenderRank |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
I=0, K=1 I=0, K=1
Figure 11: Compressing SenderRank Figure 12: Compressing SenderRank.
In Figure 12, the RPLInstanceID is not the Global RPLInstanceID 0, In Figure 13, the RPLInstanceID is not the Global RPLInstanceID 0,
and both bytes of the SenderRank are significant: and both bytes of the SenderRank are significant:
0 1 2 3 0 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|0|0|O|R|F|0|0| 6LoRH Type=5 | RPLInstanceID | Sender-... |1|0|0|O|R|F|0|0| 6LoRH Type=5 | RPLInstanceID | Sender-...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...-Rank | ...-Rank |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
I=0, K=0 I=0, K=0
Figure 12: Least compressed form of RPI-6LoRH Figure 13: Least compressed form of RPI-6LoRH.
A typical packet in RPL non-storing mode going down the RPL graph
requires an IPinIP encapsulating the RH3, whereas the RPI is usually
omitted, unless it is important to indicate the RPLInstanceID. To
match this structure, an optimized IPinIP 6LoRH is defined in
Section 8.
And the types include the setting of I and K as follows:
+-----------+-------+-------+
| Type | I | K |
+-----------+-------+-------+
| 5 | 0 | 0 |
| 6 | 0 | 1 |
| 7 | 1 | 0 |
| 8 | 1 | 1 |
+-----------+-------+-------+
Figure 13: The RPI-6LoRH Types
8. The IP-in-IP 6LoRH 8. The IP-in-IP 6LoRH
The IP-in-IP 6LoRH (IPinIP-6LoRH) is an Elective 6LoWPAN Routing The IP-in-IP 6LoRH (IPinIP-6LoRH) is an Elective 6LoWPAN Routing
Header that provides a compressed form for the encapsulating IPv6 Header that provides a compressed form for the encapsulating IPv6
Header in the case of an IP-in-IP encapsulation. Header in the case of an IP-in-IP encapsulation.
An IPinIP encapsulation is used to insert a field such as a Routing An IP-in-IP encapsulation is used to insert a field such as a Routing
Header or an RPI at a router that is not the source of the packet. Header or an RPI at a router that is not the source of the packet.
In order to send an error back regarding the inserted field, the In order to send an error back regarding the inserted field, the
address of the router that performs the insertion must be provided. address of the router that performs the insertion must be provided.
The encapsulation can also enable a router down the path removing a The encapsulation can also enable the last router prior to
field such as the RPI, but this can be done in the compressed form by Destination to remove a field such as the RPI, but this can be done
removing the RPI-6LoRH, so an IPinIP-6LoRH encapsulation is not in the compressed form by removing the RPI-6LoRH, so an IPinIP-6LoRH
required for that sole purpose. encapsulation is not required for that sole purpose.
This field is not critical for routing so the Type can be ignored, This field is not critical for routing so the Type can be ignored,
and the TSE field contains the Length in bytes. and the TSE field contains the Length in bytes.
0 1 2 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
|1|0|1| Length | 6LoRH Type 6 | Hop Limit | Encaps. Address | |1|0|1| Length | 6LoRH Type 6 | Hop Limit | Encaps. Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ... -+
Figure 14: The IPinIP-6LoRH Figure 14: The IPinIP-6LoRH.
The Length of an IPinIP-6LoRH is expressed in bytes and MUST be at The Length of an IPinIP-6LoRH is expressed in bytes and MUST be at
least 1, to indicate a Hop Limit (HL), that is decremented at each least 1, to indicate a Hop Limit (HL), that is decremented at each
hop. When the HL reaches 0, the packet is dropped per [RFC2460] hop. When the HL reaches 0, the packet is dropped per [RFC2460]
If the Length of an IPinIP-6LoRH is exactly 1, then the Encapsulator If the Length of an IPinIP-6LoRH is exactly 1, then the Encapsulator
Address is elided, which means that the Encapsulator is a well-known Address is elided, which means that the Encapsulator is a well-known
router, for instance the root in a RPL graph. router, for instance the root in a RPL graph.
If the Length of an IPinIP-6LoRH is strictly more than 1, then an If the Length of an IPinIP-6LoRH is strictly more than 1, then an
skipping to change at page 17, line 18 skipping to change at page 17, line 27
Type, and assigns the following values: Type, and assigns the following values:
0..4 : RH3-6LoRH [RFCthis] 0..4 : RH3-6LoRH [RFCthis]
5 : RPI-6LoRH [RFCthis] 5 : RPI-6LoRH [RFCthis]
6 : IPinIP-6LoRH [RFCthis] 6 : IPinIP-6LoRH [RFCthis]
11. Acknowledgments 11. Acknowledgments
The authors wish to thank Martin Turon, James Woodyatt, Samita The authors wish to thank Thomas Watteyne, Tengfei Chang, Martin
Chakrabarti, Jonathan Hui, Gabriel Montenegro and Ralph Droms for Turon, James Woodyatt, Samita Chakrabarti, Jonathan Hui, Gabriel
constructive reviews to the design in the 6lo Working Group. The Montenegro and Ralph Droms for constructive reviews to the design in
overall discussion involved participants to the 6MAN, 6TiSCH and ROLL the 6lo Working Group. The overall discussion involved participants
WGs, thank you all. Special thanks to the chairs of the ROLL WG, to the 6MAN, 6TiSCH and ROLL WGs, thank you all. Special thanks to
Michael Richardson and Ines Robles, and Brian Haberman, Internet Area the chairs of the ROLL WG, Michael Richardson and Ines Robles, and
A-D, and Adrian Farrel, Routing Area A-D, for driving this complex Brian Haberman, Internet Area A-D, and Adrian Farrel, Routing Area
effort across Working Groups and Areas. A-D, for driving this complex effort across Working Groups and Areas.
12. References 12. References
12.1. Normative References 12.1. Normative References
[IEEE802154] [IEEE802154]
IEEE standard for Information Technology, "IEEE std. IEEE standard for Information Technology, "IEEE std.
802.15.4, Part. 15.4: Wireless Medium Access Control (MAC) 802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
and Physical Layer (PHY) Specifications for Low-Rate and Physical Layer (PHY) Specifications for Low-Rate
Wireless Personal Area Networks", 2015. Wireless Personal Area Networks", 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
DOI 10.17487/RFC2119, March 1997, RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>. December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4 "Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<http://www.rfc-editor.org/info/rfc4944>. <http://www.rfc-editor.org/info/rfc4944>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<http://www.rfc-editor.org/info/rfc6282>. <http://www.rfc-editor.org/info/rfc6282>.
[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550, Low-Power and Lossy Networks", RFC 6550, DOI 10.17487/
DOI 10.17487/RFC6550, March 2012, RFC6550, March 2012,
<http://www.rfc-editor.org/info/rfc6550>. <http://www.rfc-editor.org/info/rfc6550>.
[RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing [RFC6552] Thubert, P., Ed., "Objective Function Zero for the Routing
Protocol for Low-Power and Lossy Networks (RPL)", Protocol for Low-Power and Lossy Networks (RPL)", RFC
RFC 6552, DOI 10.17487/RFC6552, March 2012, 6552, DOI 10.17487/RFC6552, March 2012,
<http://www.rfc-editor.org/info/rfc6552>. <http://www.rfc-editor.org/info/rfc6552>.
[RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low-
Power and Lossy Networks (RPL) Option for Carrying RPL Power and Lossy Networks (RPL) Option for Carrying RPL
Information in Data-Plane Datagrams", RFC 6553, Information in Data-Plane Datagrams", RFC 6553, DOI
DOI 10.17487/RFC6553, March 2012, 10.17487/RFC6553, March 2012,
<http://www.rfc-editor.org/info/rfc6553>. <http://www.rfc-editor.org/info/rfc6553>.
[RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6
Routing Header for Source Routes with the Routing Protocol Routing Header for Source Routes with the Routing Protocol
for Low-Power and Lossy Networks (RPL)", RFC 6554, for Low-Power and Lossy Networks (RPL)", RFC 6554, DOI
DOI 10.17487/RFC6554, March 2012, 10.17487/RFC6554, March 2012,
<http://www.rfc-editor.org/info/rfc6554>. <http://www.rfc-editor.org/info/rfc6554>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and [RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <http://www.rfc-editor.org/info/rfc7102>. 2014, <http://www.rfc-editor.org/info/rfc7102>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228, DOI 10.17487/
DOI 10.17487/RFC7228, May 2014, RFC7228, May 2014,
<http://www.rfc-editor.org/info/rfc7228>. <http://www.rfc-editor.org/info/rfc7228>.
12.2. Informative References 12.2. Informative References
[I-D.bergmann-bier-ccast]
Bergmann, O., Bormann, C., and S. Gerdes, "Constrained-
Cast: Source-Routed Multicast for RPL", draft-bergmann-
bier-ccast-00 (work in progress), November 2014.
[I-D.ietf-6tisch-architecture] [I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-08 (work of IEEE 802.15.4", draft-ietf-6tisch-architecture-09 (work
in progress), May 2015. in progress), November 2015.
[I-D.ietf-6tisch-tsch] [I-D.robles-roll-useofrplinfo]
Watteyne, T., Palattella, M., and L. Grieco, "Using Robles, I., Richardson, M., and P. Thubert, "When to use
IEEE802.15.4e TSCH in an IoT context: Overview, Problem RFC 6553, 6554 and IPv6-in-IPv6", draft-robles-roll-
Statement and Goals", draft-ietf-6tisch-tsch-06 (work in useofrplinfo-02 (work in progress), October 2015.
progress), March 2015.
[I-D.thubert-6lo-forwarding-fragments] [I-D.thubert-6lo-forwarding-fragments]
Thubert, P. and J. Hui, "LLN Fragment Forwarding and Thubert, P. and J. Hui, "LLN Fragment Forwarding and
Recovery", draft-thubert-6lo-forwarding-fragments-02 (work Recovery", draft-thubert-6lo-forwarding-fragments-02 (work
in progress), November 2014. in progress), November 2014.
[I-D.wijnands-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-wijnands-bier-architecture-05 (work in
progress), March 2015.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C. [RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)", Low-Power Wireless Personal Area Networks (6LoWPANs)", RFC
RFC 6775, DOI 10.17487/RFC6775, November 2012, 6775, DOI 10.17487/RFC6775, November 2012,
<http://www.rfc-editor.org/info/rfc6775>. <http://www.rfc-editor.org/info/rfc6775>.
[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
Internet of Things (IoT): Problem Statement", RFC 7554,
DOI 10.17487/RFC7554, May 2015,
<http://www.rfc-editor.org/info/rfc7554>.
Appendix A. Examples
The example in Figure 15 illustrates the 6LoRH compression of a
classical packet in Storing Mode in all directions, as well as in
non-Storing mode for a packet going up the DODAG following the
default route to the root. In this particular example, a
fragmentation process takes place per [RFC4944], and the fragment
headers must be placed in Page 0 before switching to Page 1:
+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+- ...
|Frag type|Frag hdr |11110001| IPinIP | RPI | Dispatch + LOWPAN_IPHC
|RFC 4944 |RFC 4944 | Page 1 | 6LoRH | 6LoRH | RFC 6282
+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+- ...
<- RFC 6282 ->
No RPL artifact
Figure 15: Example Compressed Packet with RPI.
The example illustrated in Figure 16 is a classical packet in non-
Storing mode for a packet going down the DODAG following a source
routed path from the root; in this particular example, addresses in
the DODAG are assigned to share a same /112 prefix, for instance
taken from a /64 subnet with the first 6 octets of the suffix set to
a constant such as all zeroes. In that case, all addresses but the
first can be compressed to 2 octets, which means that there will be 2
RH3_6LoRH headers, one to store the first complete address and the
one to store the sequence of addresses compressed to 2 octets (in
this example, 3 of them):
+- ... -+- ... -+-+-+- ... -+-+-+-+-+ ... -+-+-+-+-+-+-+-+-+-+-+- ...
|11110001| IPinIP | RH3(128bits)| RH3(3*16bits)| Dispatch + LOWPAN_IPHC
|Page 1 | 6LoRH | 6LoRH | 6LoRH | RFC 6282
+- ... -+- ... +-+-+-+- ... -+-+-+-+-+ ... -+-+-+-+-+-+-+-+-+-+-+- ...
<- RFC 6282 ->
No RPL artifact
Figure 16: Example Compressed Packet with RH3.
Note: the RPI is not represented since most implementations actually
refrain from placing it in a source routed packet though [RFC6550]
generally expects it.
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems Cisco Systems
Village d'Entreprises Green Side Building D - Regus
400, Avenue de Roumanille 45 Allee des Ormes
Batiment T3 BP1200
Biot - Sophia Antipolis 06410 MOUGINS - Sophia Antipolis 06254
FRANCE FRANCE
Phone: +33 4 97 23 26 34 Phone: +33 4 97 23 26 34
Email: pthubert@cisco.com Email: pthubert@cisco.com
Carsten Bormann Carsten Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
Postfach 330440 Postfach 330440
Bremen D-28359 Bremen D-28359
Germany Germany
Phone: +49-421-218-63921 Phone: +49-421-218-63921
Email: cabo@tzi.org Email: cabo@tzi.org
Laurent Toutain Laurent Toutain
Institut MINES TELECOM; TELECOM Bretagne Institut MINES TELECOM; TELECOM Bretagne
2 rue de la Chataigneraie 2 rue de la Chataigneraie
CS 17607 CS 17607
Cesson-Sevigne Cedex 35576 Cesson-Sevigne Cedex 35576
France France
Email: Laurent.Toutain@telecom-bretagne.eu Email: Laurent.Toutain@telecom-bretagne.eu
Robert Cragie Robert Cragie
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