draft-ietf-6lo-routing-dispatch-04.txt   draft-ietf-6lo-routing-dispatch-05.txt 
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track C. Bormann Intended status: Standards Track C. Bormann
Expires: July 26, 2016 Uni Bremen TZI Expires: August 15, 2016 Uni Bremen TZI
L. Toutain L. Toutain
IMT-TELECOM Bretagne IMT-TELECOM Bretagne
R. Cragie R. Cragie
ARM ARM
January 23, 2016 February 12, 2016
6LoWPAN Routing Header 6LoWPAN Routing Header
draft-ietf-6lo-routing-dispatch-04 draft-ietf-6lo-routing-dispatch-05
Abstract Abstract
This specification introduces a new 6LoWPAN dispatch type for use in This specification introduces a new 6LoWPAN dispatch type for use in
6LoWPAN Route-Over topologies, that initially covers the needs of RPL 6LoWPAN Route-Over topologies, that initially covers the needs of RPL
(RFC6550) data packets compression. Using this dispatch type, this (RFC6550) data packets compression. Using this dispatch type, 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-
IP technique and is extensible for more applications. IP technique and is extensible for more applications.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 26, 2016. This Internet-Draft will expire on August 15, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.1. New Routing Header Dispatch (6LoRH) . . . . . . . . . . . 6 3.1. New Routing Header Dispatch (6LoRH) . . . . . . . . . . . 6
3.2. Placement Of 6LoRH headers . . . . . . . . . . . . . . . 6 3.2. Placement Of 6LoRH headers . . . . . . . . . . . . . . . 6
3.2.1. Relative To Non-6LoRH Headers . . . . . . . . . . . . 7 3.2.1. Relative To Non-6LoRH Headers . . . . . . . . . . . . 7
3.2.2. Relative To Other 6LoRH Headers . . . . . . . . . . . 7 3.2.2. Relative To Other 6LoRH Headers . . . . . . . . . . . 7
4. 6LoWPAN Routing Header General Format . . . . . . . . . . . . 8 4. 6LoWPAN Routing Header General Format . . . . . . . . . . . . 8
4.1. Elective Format . . . . . . . . . . . . . . . . . . . . . 8 4.1. Elective Format . . . . . . . . . . . . . . . . . . . . . 8
4.2. Critical Format . . . . . . . . . . . . . . . . . . . . . 9 4.2. Critical Format . . . . . . . . . . . . . . . . . . . . . 9
4.3. Compressing Addresses . . . . . . . . . . . . . . . . . . 9 4.3. Compressing Addresses . . . . . . . . . . . . . . . . . . 9
4.3.1. Coalescence . . . . . . . . . . . . . . . . . . . . . 10 4.3.1. Coalescence . . . . . . . . . . . . . . . . . . . . . 10
4.3.2. DODAG Root Address Determination . . . . . . . . . . 10 4.3.2. DODAG Root Address Determination . . . . . . . . . . 10
5. The Routing Header Type 3 (RH3) 6LoRH Header . . . . . . . . 11 5. The SRH 6LoRH Header . . . . . . . . . . . . . . . . . . . . 11
5.1. RH3-6LoRH General Operation . . . . . . . . . . . . . . . 13 5.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2. The Design Point of Popping Entries . . . . . . . . . . . 13 5.2. SRH-6LoRH General Operation . . . . . . . . . . . . . . . 13
5.3. Compression Reference . . . . . . . . . . . . . . . . . . 14 5.2.1. Uncompressed SRH Operation . . . . . . . . . . . . . 13
5.4. Popping Headers . . . . . . . . . . . . . . . . . . . . . 15 5.2.2. 6LoRH-Compressed SRH Operation . . . . . . . . . . . 13
5.5. Forwarding . . . . . . . . . . . . . . . . . . . . . . . 16 5.2.3. Inner LOWPAN_IPHC Compression . . . . . . . . . . . . 14
6. The RPL Packet Information 6LoRH . . . . . . . . . . . . . . 16 5.3. The Design Point of Popping Entries . . . . . . . . . . . 14
6.1. Compressing the RPLInstanceID . . . . . . . . . . . . . . 18 5.4. Compression Reference for SRH-6LoRH header entries . . . 15
6.2. Compressing the SenderRank . . . . . . . . . . . . . . . 18 5.5. Popping Headers . . . . . . . . . . . . . . . . . . . . . 16
5.6. Forwarding . . . . . . . . . . . . . . . . . . . . . . . 17
6. The RPL Packet Information 6LoRH . . . . . . . . . . . . . . 17
6.1. Compressing the RPLInstanceID . . . . . . . . . . . . . . 19
6.2. Compressing the SenderRank . . . . . . . . . . . . . . . 19
6.3. The Overall RPI-6LoRH encoding . . . . . . . . . . . . . 19 6.3. The Overall RPI-6LoRH encoding . . . . . . . . . . . . . 19
7. The IP-in-IP 6LoRH Header . . . . . . . . . . . . . . . . . . 21 7. The IP-in-IP 6LoRH Header . . . . . . . . . . . . . . . . . . 22
8. Security Considerations . . . . . . . . . . . . . . . . . . . 22 8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
9.1. Reserving Space in 6LoWPAN Dispatch Page 1 . . . . . . . 22 9.1. Reserving Space in 6LoWPAN Dispatch Page 1 . . . . . . . 23
9.2. New 6LoWPAN Routing Header Type Registry . . . . . . . . 23 9.2. New 6LoWPAN Routing Header Type Registry . . . . . . . . 24
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
11.1. Normative References . . . . . . . . . . . . . . . . . . 23 11.1. Normative References . . . . . . . . . . . . . . . . . . 24
11.2. Informative References . . . . . . . . . . . . . . . . . 24 11.2. Informative References . . . . . . . . . . . . . . . . . 25
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 25 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 26
A.1. Examples Compressing The RPI . . . . . . . . . . . . . . 25 A.1. Examples Compressing The RPI . . . . . . . . . . . . . . 26
A.2. Example Of Downward Packet In Non-Storing Mode . . . . . 27 A.2. Example Of Downward Packet In Non-Storing Mode . . . . . 28
A.3. Example of RH3-6LoRH life-cycle . . . . . . . . . . . . . 28 A.3. Example of SRH-6LoRH life-cycle . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
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, a very constrained resource in most cases. focused on saving energy, a very constrained resource in most cases.
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
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implementations. implementations.
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. Option (RPL-OPT) that is placed in an IPv6 Hop-by-Hop header.
This representation demands a total of 8 bytes, while in most cases This representation demands a total of 8 bytes, while in most cases
the actual RPI payload requires only 19 bits. Since the Hop-by-Hop the actual RPI payload requires only 19 bits. Since the Hop-by-Hop
header must not flow outside of the RPL domain, it must be inserted header must not flow outside of the RPL domain, it must be inserted
in packets entering the domain and be removed from packets that leave in packets entering the domain and be removed from packets that leave
the domain. In both cases, this operation implies an IP-in-IP the domain. In both cases, this operation implies an IP-in-IP
encapsulation. encapsulation.
Additionally, in the case of the Non-Storing Mode of Operation (MOP),
RPL requires a Source Routing Header (SRH) in all packets that are
routed down a RPL graph. for that purpose, the [IPv6 Routing Header
for Source Routes with RPL] (#RFC6554) specification defines the type
3 Routing Header for IPv6 (RH3).
------+--------- ^ ------+--------- ^
| Internet | | Internet |
| | Native IPv6 | | Native IPv6
+-----+ | +-----+ |
| | Border Router (RPL Root) ^ | ^ | | Border Router (RPL Root) ^ | ^
| | | | | | | | | |
+-----+ | | | IPv6 in +-----+ | | | IPv6 in
| | | | IPv6 | | | | IPv6
o o o o | | | + RPI o o o o | | | plus
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 | | | RPL SRH
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 2: 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), With Non-Storing RPL, even if the source is a node in the same LLN,
RPL requires a Routing Header type 3 (RH3) as defined in the IPv6 the packet must first reach up the graph to the root so that the root
Routing Header for Source Routes with RPL [RFC6554] specification, can insert the SRH to go down the graph. In any fashion, whether the
for all packets that are routed down a RPL graph. With Non-Storing packet was originated in a node in the LLN or outside the LLN, and
RPL, even if the source is a node in the same LLN, the packet must regardless of whether the packet stays within the LLN or not, as long
first reach up the graph to the root so that the root can insert the as the source of the packet is not the root itself, the source-
RH3 to go down the graph. In any fashion, whether the packet was routing operation also implies an IP-in-IP encapsulation at the root
originated in a node in the LLN or outside the LLN, and regardless of in order to insert the SRH.
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
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 [RFC7554] (TSCH) mode of over the TimeSlotted Channel Hopping [RFC7554] (TSCH) mode of
operation of IEEE 802.15.4. The architecture requires the use of operation of IEEE 802.15.4. The architecture requires the use of
both RPL and the 6lo adaptation layer over IEEE 802.15.4. Because it both RPL and the 6lo adaptation layer over IEEE 802.15.4. Because it
inherits the constraints on frame size from the MAC layer, 6TiSCH inherits the constraints on frame size from the MAC layer, 6TiSCH
cannot afford to allocate 8 bytes per packet on the RPI. Hence the cannot afford to allocate 8 bytes per packet on the RPI. Hence the
requirement for 6LoWPAN header compression of the RPI. requirement for 6LoWPAN header compression of the RPI.
An extensible compression technique is required that simplifies IP- An extensible compression technique is required that simplifies IP-
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parser, a context being identified by a Page number. The parser, a context being identified by a Page number. The
specification defines 16 Pages. specification defines 16 Pages.
This draft operates within Page 1, which is indicated by a Dispatch This draft operates within Page 1, which is indicated by a Dispatch
Value of binary 11110001. Value of binary 11110001.
3.1. New Routing Header Dispatch (6LoRH) 3.1. 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 SRH, as well as other sorts
of routing information such as the RPI and IP-in-IP encapsulation. of routing information such as the RPI and IP-in-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 use. (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. Section 4 describes how RPL artifacts in data new 6LoRH Dispatch. Section 4 describes how RPL artifacts in data
packets can be compressed as 6LoRH headers. packets can be compressed as 6LoRH headers.
3.2. Placement Of 6LoRH headers 3.2. Placement Of 6LoRH headers
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stripped from the packet, the whole chain goes with it. When one or stripped from the packet, the whole chain goes with it. When one or
more header(s) are inserted by an intermediate router, that router more header(s) are inserted by an intermediate router, that router
normally chains the headers and encapsulates the result in IP-in-IP. normally chains the headers and encapsulates the result in IP-in-IP.
With this specification, the chains of headers MUST be compressed in With this specification, the chains of headers MUST be compressed in
the same order as they appear in the uncompressed form of the packet. the same order as they appear in the uncompressed form of the packet.
This means that if there is more than one nested IP-in-IP This means that if there is more than one nested IP-in-IP
encapsulations, the first IP-in-IP encapsulation, with all its chain encapsulations, the first IP-in-IP encapsulation, with all its chain
of headers, is encoded first in the compressed form. of headers, is encoded first in the compressed form.
In the compressed form of a packet that has RH3 or HbH headers after In the compressed form of a packet that has SRH or HbH headers after
the inner IPv6 header (e.g. if there is no IP-in-IP encapsulation), the inner IPv6 header (e.g. if there is no IP-in-IP encapsulation),
these headers are placed in the 6LoRH form before the 6LOWPAN-IPHC these headers are placed in the 6LoRH form before the 6LOWPAN-IPHC
that represents the IPv6 header Section 3.2.1. If this packet gets that represents the IPv6 header Section 3.2.1. If this packet gets
encapsulated and some other RH3 or HbH headers are added as part of encapsulated and some other SRH or HbH headers are added as part of
the encapsulation, placing the 6LoRH headers next to one another may the encapsulation, placing the 6LoRH headers next to one another may
present an ambiguity on which header belong to which chain in the present an ambiguity on which header belong to which chain in the
uncompressed form. uncompressed form.
In order to disambiguate the headers that follow the inner IPv6 In order to disambiguate the headers that follow the inner IPv6
header in the uncompressed form from the headers that follow the header in the uncompressed form from the headers that follow the
outer IP-in-IP header, it is REQUIRED that the compressed IP-in-IP outer IP-in-IP header, it is REQUIRED that the compressed IP-in-IP
header is placed last in the encoded chain. This means that the header is placed last in the encoded chain. This means that the
6LoRH headers that are found after the last compressed IP-in-IP 6LoRH headers that are found after the last compressed IP-in-IP
header are to be inserted after the IPv6 header that is encoded with header are to be inserted after the IPv6 header that is encoded with
the 6LOWPAN-IPHC when decompressing the packet. the 6LOWPAN-IPHC when decompressing the packet.
With regards to the relative placement of the RH3 and the RPI in the With regards to the relative placement of the SRH and the RPI in the
compressed form, it is a design point for this specification that the compressed form, it is a design point for this specification that the
RH3 entries are consumed as the packet progresses down the LLN SRH entries are consumed as the packet progresses down the LLN
Section 5.2. In order to make this operation simpler in the Section 5.3. In order to make this operation simpler in the
compressed form, it is REQUIRED that the in the compressed form, the compressed form, it is REQUIRED that the in the compressed form, the
addresses along the source route path are encoded in the order of the addresses along the source route path are encoded in the order of the
path, and that the compressed RH3 are placed before the compressed path, and that the compressed SRH are placed before the compressed
RPI. RPI.
4. 6LoWPAN Routing Header General Format 4. 6LoWPAN Routing Header General Format
The 6LoRH usesthe Dispatch Value Bit Pattern of 10xxxxxx in Page 1. The 6LoRH usesthe Dispatch Value Bit Pattern of 10xxxxxx in Page 1.
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
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4.3. Compressing Addresses 4.3. Compressing Addresses
The general technique used in this draft to compress an address is The general technique used in this draft to compress an address is
first to determine a reference that as a long prefix match with this first to determine a reference that as a long prefix match with this
address, and then elide that matching piece. In order to reconstruct address, and then elide that matching piece. In order to reconstruct
the compress address, the receiving node will perform the process of the compress address, the receiving node will perform the process of
coalescence described in section Section 4.3.1. coalescence described in section Section 4.3.1.
One possible reference is the root of the RPL DODAG that is being One possible reference is the root of the RPL DODAG that is being
traversed. It is used to compress an outer IP-in-IP header, and if traversed. It is used by 6LoRH as the reference to compress an outer
the root is the source of the packet, the technique allows to fully IP header, in case of an IP-in-IP encapsulation. If the root is the
elide the source address in the compressed form of the IP header. If source of the packet, this technique allows to fully elide the source
the root is not the encapsulator, then the encapsulator address may address in the compressed form of the IP header. If the root is not
still be compressed using the root as reference. How the address of the encapsulator, then the encapsulator address may still be
the root is determined is discussed in Section 4.3.2. compressed using the root as reference. How the address of the root
is determined is discussed in Section 4.3.2.
Once the address of the source of the packet is determined, it Once the address of the source of the packet is determined, it
becomes the reference for the compression of the addresses that are becomes the reference for the compression of the addresses that are
located in compressed RH3 headers that are present inside the IP-in- located in compressed SRH headers that are present inside the IP-in-
IP encapsulation in the uncompressed form. IP encapsulation in the uncompressed form.
4.3.1. Coalescence 4.3.1. Coalescence
An IPv6 compressed address is coalesced with a reference address by An IPv6 compressed address is coalesced with a reference address by
overriding the N rightmost bytes of the reference address with the overriding the N rightmost bytes of the reference address with the
compressed address, where N is the length of the compressed address, compressed address, where N is the length of the compressed address,
as indicated by the Type of the RH3-6LoRH header in Figure 7. as indicated by the Type of the SRH-6LoRH header in Figure 7.
The reference address MAY be a compressed address as well, in which The reference address MAY be a compressed address as well, in which
case it MUST be compressed in a form that is of an equal or greater case it MUST be compressed in a form that is of an equal or greater
length than the address that is being coalesced. length than the address that is being coalesced.
A compressed address is expanded by coalescing it with a reference A compressed address is expanded by coalescing it with a reference
address. In the particular case of a Type 4 RH3-6LoRH, the address address. In the particular case of a Type 4 SRH-6LoRH, the address
is expressed in full and the coalescence is a complete override as is expressed in full and the coalescence is a complete override as
illustrated in Figure 5. illustrated in Figure 5.
RRRRRRRRRRRRRRRRRRRR reference address, may be compressed or not RRRRRRRRRRRRRRRRRRRR reference address, may be compressed or not
CCCCCCC compressed address, shorter or same as reference CCCCCCC compressed address, shorter or same as reference
RRRRRRRRRRRRRCCCCCCC Coalesced address, same compression as reference RRRRRRRRRRRRRCCCCCCC Coalesced address, same compression as reference
Figure 5: Coalescing addresses. Figure 5: Coalescing addresses.
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With [RFC6282], the state is provided to the stack by the 6LoWPAN With [RFC6282], the state is provided to the stack by the 6LoWPAN
Neighbor Discovery Protocol (NDP) [RFC6775]. NDP exchanges the Neighbor Discovery Protocol (NDP) [RFC6775]. NDP exchanges the
context through 6LoWPAN Context Option in Router Advertisement (RA) context through 6LoWPAN Context Option in Router Advertisement (RA)
messages. In the compressed form of the packet, the context can be messages. In the compressed form of the packet, the context can be
signaled in a Context Identifier Extension. signaled in a Context Identifier Extension.
With this specification, the compression information is provided to With this specification, the compression information is provided to
the stack by RPL, and RPL exchanges it through the DODAGID field in the stack by RPL, and RPL exchanges it through the DODAGID field in
the DAG Information Object (DIO) messages, as described in more the DAG Information Object (DIO) messages, as described in more
details below. In the compressed form of the packet, the context can details below. In the compressed form of the packet, the context can
be signaled in by the InstanceID in the RPI. be signaled in by the RPLInstanceID in the RPI.
With RPL [RFC6550], the address of DODAG root is known from the With RPL [RFC6550], the address of the DODAG root is known from the
DODAGID field of the DIO messages. For a Global Instance, the DODAGID field of the DIO messages. For a Global Instance, the
RPLInstanceID that is present in the RPI is enough information to RPLInstanceID that is present in the RPI is enough information to
identify the DODAG that this node participates to and its associated identify the DODAG that this node participates to and its associated
root. But for a Local Instance, the address of the root MUST be root. But for a Local Instance, the address of the root MUST be
explicit, either in some device configuration or signaled in the explicit, either in some device configuration or signaled in the
packet, as the source or the destination address, respectively. packet, as the source or the destination address, respectively.
When implicit, the address of the DODAG root MUST be determined as When implicit, the address of the DODAG root MUST be determined as
follows: follows:
If the whole network is a single DODAG then the root can be well- If the whole network is a single DODAG then the root can be well-
known and does not need to be signaled in the packets. But RPL does known and does not need to be signaled in the packets. But since RPL
not expose that property and it can only be known by a configuration does not expose that property, it can only be known by a
applied to all nodes. configuration applied to all nodes.
Else, the router that encapsulates the packet and compresses it with Else, the router that encapsulates the packet and compresses it with
this specification MUST also place an RPI in the packet as prescribed this specification MUST also place an RPI in the packet as prescribed
by [RFC6550] to enable the identification of the DODAG. The RPI must by [RFC6550] to enable the identification of the DODAG. The RPI must
be present even in the case when the router also places an RH3 header be present even in the case when the router also places an SRH header
in the packet. in the packet.
It is expected that the RPL implementation provides an abstract It is expected that the RPL implementation maintains an abstract
context table, indexed by Global RPLInstanceID, that provides the context table, indexed by Global RPLInstanceID, that provides the
address of the root of the DODAG that this nodes participates to for address of the root of the DODAG that this nodes participates to for
that particular Instance. that particular RPL Instance.
5. The Routing Header Type 3 (RH3) 6LoRH Header 5. The SRH 6LoRH Header
## Encoding {#RH3-6LoRH-encoding} 5.1. Encoding
The Routing Header type 3 (RH3) 6LoRH (RH3-6LoRH) header is a The Source Routing Header 6LoRH (SRH-6LoRH) header is a Critical
Critical 6LoWPAN Routing Header that provides a compressed form for 6LoWPAN Routing Header that provides a compressed form for the SRH,
the RH3, as defined in [RFC6554] for use by RPL routers. Routers as defined in [RFC6554] for use by RPL routers. Routers that need to
that need to forward a packet with a RH3-6LoRH are expected to be RPL forward a packet with a SRH-6LoRH are expected to be RPL routers and
routers and are expected to support this specification. If a non-RPL are expected to support this specification. If a non-RPL router
router receives a packet with a RH3-6LoRH, this means that there was receives a packet with a SRH-6LoRH, this means that there was a
a routing error and the packet should be dropped so the Type cannot routing error and the packet should be dropped so the Type cannot be
be ignored. 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 6: The RH3-6LoRH. Figure 6: The SRH-6LoRH.
The 6LoRH Type indicates the compression level used in a given The 6LoRH Type indicates the compression level used in a given SRH-
RH3-6LoRH header. 6LoRH header.
One or more 6LoRH header(s) MAY be placed in a 6LoWPAN packet. One or more 6LoRH header(s) MAY be placed in a 6LoWPAN packet.
It results that all addresses in a given RH3-6LoRH header MUST be It results that all addresses in a given SRH-6LoRH header MUST be
compressed in an identical fashion, down to using the identical compressed in an identical fashion, down to using the identical
number of bytes per address. In order to get different degrees of number of bytes per address. In order to get different degrees of
compression, multiple consecutive RH3-6LoRH headers MUST be used. compression, multiple consecutive SRH-6LoRH headers MUST be used.
Type 0 means that the address is compressed down to one byte, whereas Type 0 means that the address is compressed down to one byte, whereas
Type 4 means that the address is provided in full in the RH3-6LoRH Type 4 means that the address is provided in full in the SRH-6LoRH
with no compression. The complete list of Types of RH3-6LoRH and the with no compression. The complete list of Types of SRH-6LoRH and the
corresponding compression level are provided in Figure 7: corresponding compression level are provided in Figure 7:
+-----------+----------------------+ +-----------+----------------------+
| 6LoRH | Length of compressed | | 6LoRH | Length of compressed |
| Type | IPv6 address (bytes) | | Type | IPv6 address (bytes) |
+-----------+----------------------+ +-----------+----------------------+
| 0 | 1 | | 0 | 1 |
| 1 | 2 | | 1 | 2 |
| 2 | 4 | | 2 | 4 |
| 3 | 8 | | 3 | 8 |
| 4 | 16 | | 4 | 16 |
+-----------+----------------------+ +-----------+----------------------+
Figure 7: The RH3-6LoRH Types. Figure 7: The SRH-6LoRH Types.
In the case of a RH3-6LoRH header, the TSE field is used as a Size, In the case of a SRH-6LoRH header, the TSE field is used as a Size,
which encodes the number of hops minus 1; so a Size of 0 means one which 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 hop, and the maximum that can be encoded is 32 hops. (If more than
32 hops need to be expressed, a sequence of RH3-6LoRH elements can be 32 hops need to be expressed, a sequence of SRH-6LoRH elements can be
employed.) It results that the Length in bytes of a RH3-6LoRH header employed.) It results that the Length in bytes of a SRH-6LoRH header
is: is:
2 + Length_of_compressed_IPv6_address * (Size + 1) 2 + Length_of_compressed_IPv6_address * (Size + 1)
5.1. RH3-6LoRH General Operation 5.2. SRH-6LoRH General Operation
5.2.1. Uncompressed SRH Operation
In the non-compressed form, when the root generates or forwards a In the non-compressed form, when the root generates or forwards a
packet in non-Storing Mode, it needs to include a Routing Header type packet in non-Storing Mode, it needs to include a Source Routing
3 (RH3) [RFC6554] to signal a strict source-route path to a final Header [RFC6554] to signal a strict source-route path to a final
destination down the DODAG. All the hops along the path, but the destination down the DODAG.
first one, are encoded in order in the RH3. The last entry in the
RH3 is the final destination and the destination in the IPv6 header
is the first hop along the source-route path. The intermediate hops
perform a swap and the Segment-Left field indicates the active entry
in the Routing Header [RFC2460]. The current destination of the
packet, which is the termination of the current segment, is indicated
at all times by the destination address of the IPv6 header.
The handling of the RH3-6LoRH is different: there is no swap, and a All the hops along the path, but the first one, are encoded in order
in the SRH. The last entry in the SRH is the final destination and
the destination in the IPv6 header is the first hop along the source-
route path. The intermediate hops perform a swap and the Segment-
Left field indicates the active entry in the Routing Header
[RFC2460].
The current destination of the packet, which is the termination of
the current segment, is indicated at all times by the destination
address of the IPv6 header.
5.2.2. 6LoRH-Compressed SRH Operation
The handling of the SRH-6LoRH is different: there is no swap, and a
forwarding router that corresponds to the first entry in the first forwarding router that corresponds to the first entry in the first
RH3-6LoRH upon reception of a packet effectively consumes that entry SRH-6LoRH upon reception of a packet effectively consumes that entry
when forwarding. This means that the size of a compressed source- when forwarding. This means that the size of a compressed source-
routed packet decreases as the packet progresses along its path and routed packet decreases as the packet progresses along its path and
that the routing information is lost along the way. This also means that the routing information is lost along the way. This also means
that an RH3 encoded with 6LoRH is not recoverable and cannot be that an SRH encoded with 6LoRH is not recoverable and cannot be
protected. protected.
When compressed with this specification, all the remaining hops MUST When compressed with this specification, all the remaining hops MUST
be encoded in order in one or more consecutive RH3-6LoRH headers. be encoded in order in one or more consecutive SRH-6LoRH headers.
Whether or not there is a RH3-6LoRH header present, the address of Whether or not there is a SRH-6LoRH header present, the address of
the final destination is indicated in the LoWPAN_IPHC at all times the final destination is indicated in the LoWPAN_IPHC at all times
along the path. Examples of this are provided in Appendix A. along the path. Examples of this are provided in Appendix A.
The current destination (termination of the current segment) for a The current destination (termination of the current segment) for a
compressed source-routed packet is indicated in the first entry of compressed source-routed packet is indicated in the first entry of
the first RH3-6LoRH. In strict source-routing, that entry MUST match the first SRH-6LoRH. In strict source-routing, that entry MUST match
an address of the router that receives the packet. an address of the router that receives the packet.
The last entry in the last RH3-6LoRH is the last router on the way to The last entry in the last SRH-6LoRH is the last router on the way to
the final destination in the LLN. It is typically a RPL parent of the final destination in the LLN. This router can be the final
the final destination, but it can also be a router acting at 6LR destination if it is found desirable to carry a whole IP-in-IP
[RFC6775] for the destination host. encapsulation all the way. Else, it is the RPL parent of the final
destination, or a router acting at 6LR [RFC6775] for the destination
host, and advertising the host as an external route to RPL.
5.2. The Design Point of Popping Entries If the SRH-6LoRH header is contained in an IP-in-IP encapsulation,
the last router removes the whole chain of headers. Otherwise, it
removes the SRH-6LoRH header only.
5.2.3. Inner LOWPAN_IPHC Compression
6LoWPAN ND [RFC6282] is designed to support more than one IPv6
address per node and per Interface Identifier (IID), an IID being
typically derived from a MAC address to optimize the LOWPAN-IPHC
compression.
Link local addresses are compressed with stateless address
compression (S/DAC=0). The other addresses are derived from
different prefixes and they can be compressed with stateful address
compression based on a context (S/DAC=1).
But stateless compression is only defined for the specific link-local
prefix as opposed to the prefix in an encapsulating header. And with
stateful compression, the compression reference is found in a
context, as opposed to an encapsulating header.
It results that in the case of an IP-in-IP encapsulation, it is
possible to compress an inner source (respectively destination) IP
address in a LOWPAN_IPHC based on the encapsulating IP header only if
stateful (context-based) compression is used. The compression will
operate only if the IID in the source (respectively the destination)
IP address in the outer and inner headers match, which usually means
that they refer to the same node . This is encoded as S/DAC = 1 and
S/AM=11. It must be noted that the outer destination address that is
used to compress the inner destination address is the last entry in
the last SRH-6LoRH header.
5.3. The Design Point of Popping Entries
In order to save energy and to optimize the chances of transmission In order to save energy and to optimize the chances of transmission
success on lossy media, it is a design point for this specification success on lossy media, it is a design point for this specification
that the entries in the RH3 that have been used are removed from the that the entries in the SRH that have been used are removed from the
packet. This creates a discrepancy from the art of IPv6 where packet. This creates a discrepancy from the art of IPv6 where
Routing Header are mutable but recoverable. Routing Header are mutable but recoverable.
With this specification, the packet can be expanded at any hop into a With this specification, the packet can be expanded at any hop into a
valid IPv6 packet, including a RH3, and compressed back. But the valid IPv6 packet, including a SRH, and compressed back. But the
packet as decompressed along the way will not carry all the consumed packet as decompressed along the way will not carry all the consumed
addresses that packet would have if it had been forwarded in the addresses that packet would have if it had been forwarded in the
uncompressed form. uncompressed form.
It is noted that: It is noted that:
The value of keeping the whole RH in an IPv6 header is for the The value of keeping the whole RH in an IPv6 header is for the
receiver to reverse it to use the symmetrical path on the way receiver to reverse it to use the symmetrical path on the way
back. back.
skipping to change at page 1, line 632 skipping to change at page 1, line 681
There is no use of reversing a RH in the present RPL There is no use of reversing a RH in the present RPL
specifications. specifications.
P2P RPL reverses a path that was learned reactively, as a part of P2P RPL reverses a path that was learned reactively, as a part of
the protocol operation, which is probably a cleaner way than a the protocol operation, which is probably a cleaner way than a
reversed echo on the data path. reversed echo on the data path.
Reversing a header is discouraged by [RFC2460] for RH0 unless it Reversing a header is discouraged by [RFC2460] for RH0 unless it
is authenticated, which requires an Authentication Header (AH). is authenticated, which requires an Authentication Header (AH).
There is no definition of an AH operation for RH3, and there is no There is no definition of an AH operation for SRH, and there is no
indication that the need exists in LLNs. indication that the need exists in LLNs.
It is noted that AH does not protect the RH on the way. AH is a It is noted that AH does not protect the RH on the way. AH is a
validation at the receiver with the sole value of enabling the validation at the receiver with the sole value of enabling the
receiver to reversing it. receiver to reversing it.
A RPL domain is usually protected by L2 security and that secures A RPL domain is usually protected by L2 security and that secures
both RPL itself and the RH in the packets, at every hop. This is both RPL itself and the RH in the packets, at every hop. This is
a better security than that provided by AH. a better security than that provided by AH.
In summary, the benefit of saving energy and lowering the chances of In summary, the benefit of saving energy and lowering the chances of
loss by sending smaller frames over the LLN are seen as overwhelming loss by sending smaller frames over the LLN are seen as overwhelming
compared to the value of possibly reversing the header. compared to the value of possibly reversing the header.
5.3. Compression Reference 5.4. Compression Reference for SRH-6LoRH header entries
In order to optimize the compression of IP addresses present in the In order to optimize the compression of IP addresses present in the
RH3 headers, this specification requires that the 6LoWPAN layer SRH headers, this specification requires that the 6LoWPAN layer
identifies an address that is used as reference for the compression. identifies an address that is used as reference for the compression.
With this specification, the Compression Reference for addresses
found in an RH3 header is the source of the IPv6 packet.
With RPL [RFC6550], an RH3 header may only be present in Non-Storing With this specification, the Compression Reference for the first
address found in an SRH header is the source of the IPv6 packet, and
then the reference for each subsequent entry is the address of its
predecessor once it is uncompressed.
With RPL [RFC6550], an SRH header may only be present in Non-Storing
mode, and it may only be placed in the packet by the root of the mode, and it may only be placed in the packet by the root of the
DODAG, which must be the source of the resulting IPv6 packet DODAG, which must be the source of the resulting IPv6 packet
[RFC2460]. In this case, the address used as Compression Reference [RFC2460]. In this case, the address used as Compression Reference
is that the address of the root, and it can be implicit when the is that the address of the root, and it can be implicit when the
address of the root is. address of the root is.
The Compression Reference MUST be determined as follows: The Compression Reference MUST be determined as follows:
The reference address may be obtained by configuration. The The reference address may be obtained by configuration. The
configuration may indicate either the address in full, or the configuration may indicate either the address in full, or the
skipping to change at page 1, line 678 skipping to change at page 1, line 730
[RFC6282]. [RFC6282].
Else, and if there is no IP-in-IP encapsulation, the source address Else, and if there is no IP-in-IP encapsulation, the source address
in the IPv6 header that is compressed with LOWPAN-IPHC is the in the IPv6 header that is compressed with LOWPAN-IPHC is the
reference for the compression. reference for the compression.
Else, and if the IP-in-IP compression specified in this document is Else, and if the IP-in-IP compression specified in this document is
used and the Encapsulator Address is provided, then the Encapsulator used and the Encapsulator Address is provided, then the Encapsulator
Address is the reference. Address is the reference.
5.4. Popping Headers 5.5. Popping Headers
Upon reception, the router checks whether the address in the first Upon reception, the router checks whether the address in the first
entry of the first RH3-6LoRH one of its own addresses. In that case, entry of the first SRH-6LoRH one of its own addresses. In that case,
router MUST consume that entry before forwarding, which is an action router MUST consume that entry before forwarding, which is an action
of popping from a stack, where the stack is effectively the sequence of popping from a stack, where the stack is effectively the sequence
of entries in consecutive RH3-6LoRH headers. of entries in consecutive SRH-6LoRH headers.
Popping an entry of an RH3-6LoRH header is a recursive action Popping an entry of an SRH-6LoRH header is a recursive action
performed as follows: performed as follows:
If the Size of the RH3-6LoRH header is 1 or more, indicating that If the Size of the SRH-6LoRH header is 1 or more, indicating that
there are at least 2 entries in the header, the router removes the there are at least 2 entries in the header, the router removes the
first entry and decrements the Size (by 1). first entry and decrements the Size (by 1).
Else (meaning that this is the last entry in the RH3-6LoRH header), Else (meaning that this is the last entry in the SRH-6LoRH header),
and if there is no next RH3-6LoRH header after this then the and if there is no next SRH-6LoRH header after this then the SRH-
RH3-6LoRH is removed. 6LoRH is removed.
Else, if there is a next RH3-6LoRH of a Type with a larger or equal Else, if there is a next SRH-6LoRH of a Type with a larger or equal
value, meaning a same or lesser compression yielding same or larger value, meaning a same or lesser compression yielding same or larger
compressed forms, then the RH3-6LoRH is removed. compressed forms, then the SRH-6LoRH is removed.
Else, the first entry of the next RH3-6LoRH is popped from the next Else, the first entry of the next SRH-6LoRH is popped from the next
RH3-6LoRH and coalesced with the first entry of this RH3-6LoRH. SRH-6LoRH and coalesced with the first entry of this SRH-6LoRH.
At the end of the process, if there is no more RH3-6LoRH in the At the end of the process, if there is no more SRH-6LoRH in the
packet, then the processing node is the last router along the source packet, then the processing node is the last router along the source
route path. route path.
5.5. Forwarding 5.6. Forwarding
When receiving a packet with a RH3-6LoRH, a router determines the When receiving a packet with a SRH-6LoRH, a router determines the
IPv6 address of the current segment endpoint. IPv6 address of the current segment endpoint.
If strict source routing is enforced and thus router is not the If strict source routing is enforced and thus router is not the
segment endpoint for the packet then this router MUST drop the segment endpoint for the packet then this router MUST drop the
packet. packet.
If this router is the current segment endpoint, then the router pops If this router is the current segment endpoint, then the router pops
its address as described in Section 5.4 and continues processing the its address as described in Section 5.5 and continues processing the
packet. packet.
If there is still a RH3-6LoRH, then the router determines the new If there is still a SRH-6LoRH, then the router determines the new
segment endpoint and routes the packet towards that endpoint. segment endpoint and routes the packet towards that endpoint.
Otherwise the router uses the destination in the inner IP header to Otherwise the router uses the destination in the inner IP header to
forward or accept the packet. forward or accept the packet.
The segment endpoint of a packet MUST be determined as follows: The segment endpoint of a packet MUST be determined as follows:
The router first determines the Compression Reference as discussed in The router first determines the Compression Reference as discussed in
Section 4.3.1. Section 4.3.1.
The router then coalesces the Compression Reference with the first The router then coalesces the Compression Reference with the first
entry of the first RH3-6LoRH header as discussed in Section 5.3. If entry of the first SRH-6LoRH header as discussed in Section 5.4. If
the type of the RH3-6LoRH header is type 4 then the coalescence is a the type of the SRH-6LoRH header is type 4 then the coalescence is a
full override. full override.
Since the Compression Reference is an uncompressed address, the Since the Compression Reference is an uncompressed address, the
coalesced IPv6 address is also expressed in the full 128bits. coalesced IPv6 address is also expressed in the full 128bits.
An example of this operation is provided in Appendix A.3. An example of this operation is provided in Appendix A.3.
6. The RPL Packet Information 6LoRH 6. 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 placed by RPL routers in IP packets for as a set of fields that are placed by RPL routers in IP packets to
the purpose of Instance Identification, as well as Loop Avoidance and identify the RPL Instance, detect anomalies and trigger corrective
Detection. actions.
In particular, the SenderRank, which is the scalar metric computed by In particular, the SenderRank, which is the scalar metric computed by
a specialized Objective Function such as [RFC6552], indicates the a specialized Objective Function such as [RFC6552], indicates the
Rank of the sender and is modified at each hop. The SenderRank field Rank of the sender and is modified at each hop. The SenderRank field
is used 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
skipping to change at page 1, line 789 skipping to change at page 1, line 841
domain. domain.
For that reason, this specification defines an IP-in-IP-6LoRH header For that reason, this specification defines an IP-in-IP-6LoRH header
in Section 7, but it must be noted that removal of a 6LoRH header in Section 7, but it must be noted that removal of a 6LoRH header
does not require manipulation of the packet in the LOWPAN_IPHC, and does not require manipulation of the packet in the LOWPAN_IPHC, and
thus, if the source address in the LOWPAN_IPHC is the node that thus, if the source address in the LOWPAN_IPHC is the node that
inserted the IP-in-IP-6LoRH header then this situation alone does not inserted the IP-in-IP-6LoRH header then this situation alone does not
mandate an IP-in-IP-6LoRH header. mandate an IP-in-IP-6LoRH header.
Note: A typical packet in RPL non-storing mode going down the RPL Note: A typical packet in RPL non-storing mode going down the RPL
graph requires an IP-in-IP encapsulation of the RH3, whereas the RPI graph requires an IP-in-IP encapsulation of the SRH, whereas the RPI
is usually (and quite illegally) omitted, unless it is important to is usually (and quite illegally) omitted, unless it is important to
indicate the RPLInstanceID. To match this structure, an optimized indicate the RPLInstanceID. To match this structure, an optimized
IP-in-IP 6LoRH header is defined in Section 7. IP-in-IP 6LoRH header is defined in Section 7.
As a result, a RPL packet may bear only an RPI-6LoRH header and no As a result, a RPL packet may bear only an RPI-6LoRH header and no
IP-in-IP-6LoRH header. In that case, the source and destination of IP-in-IP-6LoRH header. In that case, the source and destination of
the packet are specified by the LOWPAN_IPHC. the packet are specified by 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 header, which is The remainder of this section defines the RPI-6LoRH header, which is
a Critical 6LoWPAN Routing Header that is designed to transport the a Critical 6LoWPAN Routing Header that is designed to transport the
RPI in 6LoWPAN LLNs. RPI in 6LoWPAN LLNs.
6.1. Compressing the RPLInstanceID 6.1. 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 do not require more than one instance, and in such simple use cases do not require more than one RPL Instance, and in
cases, the instance is expected to be the global Instance 0. A such cases, the RPL Instance is expected to be the Global Instance 0.
global RPLInstanceID is encoded in a RPLInstanceID field as follows: A 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 8: 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.
6.2. Compressing the SenderRank 6.2. 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],
Section 3.5.1, as: Section 3.5.1, as:
skipping to change at page 1, line 879 skipping to change at page 1, line 932
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 9: The Generic RPI-6LoRH Format. Figure 9: The Generic RPI-6LoRH Format.
O, R, and F bits: The O, R, and F bits are defined in [RFC6550], O, R, and F bits: The O, R, and F bits are defined in [RFC6550],
section 11.2. section 11.2.
I bit: If it is set, the Instance ID is elided and the RPLInstanceID I bit: If it is set, the RPLInstanceID is elided and the
is the Global RPLInstanceID 0. If it is not set, the octet RPLInstanceID is the Global RPLInstanceID 0. If it is not set,
immediately following the type field contains the RPLInstanceID the octet immediately following the type field contains the
as specified in [RFC6550], section 5.1. RPLInstanceID as specified in [RFC6550], section 5.1.
K bit: If it is set, the SenderRank is compressed into one octet, K bit: If it is set, the SenderRank is compressed into one octet,
with the least significant octet elided. If it is not set, the with the least significant octet elided. If it is not set, the
SenderRank, is fully inlined as two octets. SenderRank, is fully inlined as two octets.
In Figure 10, the RPLInstanceID is the Global RPLInstanceID 0, and In Figure 10, the RPLInstanceID is the Global RPLInstanceID 0, and
the MinHopRankIncrease is a multiple of 256 so the least significant the MinHopRankIncrease is a multiple of 256 so the least significant
byte is all zeros and can be elided: byte is all zeros and can be elided:
0 1 2 0 1 2
skipping to change at page 1, line 976 skipping to change at page 1, line 1029
The Length of an IP-in-IP-6LoRH header is expressed in bytes and MUST The Length of an IP-in-IP-6LoRH header is expressed in bytes and MUST
be at least 1, to indicate a Hop Limit (HL), that is decremented at be at least 1, to indicate a Hop Limit (HL), that is decremented at
each hop. When the HL reaches 0, the packet is dropped per each hop. When the HL reaches 0, the packet is dropped per
[RFC2460]. [RFC2460].
If the Length of an IP-in-IP-6LoRH header is exactly 1, then the If the Length of an IP-in-IP-6LoRH header is exactly 1, then the
Encapsulator Address is elided, which means that the Encapsulator is Encapsulator Address is elided, which means that the Encapsulator is
a well-known router, for instance the root in a RPL graph. a well-known router, for instance the root in a RPL graph.
With this specification, an optimal compression of IP-in-IP The most efficient compression of an IP-in-IP encapsulation that can
encapsulation can be achieved if an endpoint of the packet is the be achieved with this specification is obtained when an endpoint of
root of the RPL DODAG associated to the Instance that is used to the packet is the root of the RPL DODAG associated to the RPL
forward the packet, and the root address is known implicitly as Instance that is used to forward the packet, and the root address is
opposed to signaled explicitly in the data packets. known implicitly as opposed to signaled explicitly in the data
packets.
If the Length of an IP-in-IP-6LoRH header is greater than 1, then an If the Length of an IP-in-IP-6LoRH header is greater than 1, then an
Encapsulator Address is placed in a compressed form after the Hop Encapsulator Address is placed in a compressed form after the Hop
Limit field. The value of the Length indicates which compression is Limit field. The value of the Length indicates which compression is
performed on the Encapsulator Address. For instance, a Size of 3 performed on the Encapsulator Address. For instance, a Size of 3
indicates that the Encapsulator Address is compressed to 2 bytes. indicates that the Encapsulator Address is compressed to 2 bytes.
The reference for the compression is the address of the root of the The reference for the compression is the address of the root of the
DODAG. The way the address of the root is determined is discussed in DODAG. The way the address of the root is determined is discussed in
Section 4.3.2. Section 4.3.2.
When it cannot be elided, the destination IP address of the IP-in-IP
header is transported in a RH3-6LoRH header as the first address of
the list.
With RPL, the destination address in the IP-in-IP header is With RPL, the destination address in the IP-in-IP header is
implicitly the root in the RPL graph for packets going upwards, and implicitly the root in the RPL graph for packets going upwards, and,
the destination address in the IPHC for packets going downwards. If in storing mode, it is the destination address in the IPHC for
the implicit value is correct, the destination IP address of the IP- packets going downwards. In non-storing mode, there is no implicit
in-IP encapsulation can be elided. value for packets going downwards.
If the implicit value is correct, the destination IP address of the
IP-in-IP encapsulation can be elided. Else, the destination IP
address of the IP-in-IP header is transported in a SRH-6LoRH header
as the first entry of the first of these headers.
If the final destination of the packet is a leaf that does not If the final destination of the packet is a leaf that does not
support this specification, then the chain of 6LoRH headers must be support this specification, then the chain of 6LoRH headers must be
stripped by the RPL/6LR router to which the leaf is attached. In stripped by the RPL/6LR router to which the leaf is attached. In
that example, the destination IP address of the IP-in-IP header that example, the destination IP address of the IP-in-IP header
cannot be elided. cannot be elided.
In the special case where a 6LoRH header is used to route 6LoWPAN In the special case where a 6LoRH header is used to route 6LoWPAN
fragments, the destination address is not accessible in the IPHC on fragments, the destination address is not accessible in the IPHC on
all fragments and can be elided only for the first fragment and for all fragments and can be elided only for the first fragment and for
skipping to change at page 23, line 10 skipping to change at page 24, line 10
101xxxxx: for Elective 6LoWPAN Routing Headers 101xxxxx: for Elective 6LoWPAN Routing Headers
100xxxxx: for Critical 6LoWPAN Routing Headers. 100xxxxx: for Critical 6LoWPAN Routing Headers.
9.2. New 6LoWPAN Routing Header Type Registry 9.2. New 6LoWPAN Routing Header Type Registry
This document creates an IANA registry for the 6LoWPAN Routing Header This document creates an IANA registry for the 6LoWPAN Routing Header
Type, and assigns the following values: Type, and assigns the following values:
0..4: RH3-6LoRH [RFCthis] 0..4: SRH-6LoRH [RFCthis]
5: RPI-6LoRH [RFCthis] 5: RPI-6LoRH [RFCthis]
6: IP-in-IP-6LoRH [RFCthis] 6: IP-in-IP-6LoRH [RFCthis]
10. Acknowledgments 10. Acknowledgments
The authors wish to thank Tom Phinney, Thomas Watteyne, Tengfei The authors wish to thank Tom Phinney, Thomas Watteyne, Tengfei
Chang, Martin Turon, James Woodyatt, Samita Chakrabarti, Jonathan Chang, Martin Turon, James Woodyatt, Samita Chakrabarti, Jonathan
Hui, Gabriel Montenegro and Ralph Droms for constructive reviews to Hui, Gabriel Montenegro and Ralph Droms for constructive reviews to
skipping to change at page 23, line 43 skipping to change at page 24, line 43
Thubert, P., "6LoWPAN Paging Dispatch", draft-ietf-6lo- Thubert, P., "6LoWPAN Paging Dispatch", draft-ietf-6lo-
paging-dispatch-01 (work in progress), January 2016. paging-dispatch-01 (work in progress), January 2016.
[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>.
11.2. Informative References 11.2. Informative References
[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-09 (work of IEEE 802.15.4", draft-ietf-6tisch-architecture-09 (work
in progress), November 2015. in progress), November 2015.
[I-D.robles-roll-useofrplinfo] [I-D.robles-roll-useofrplinfo]
skipping to change at page 25, line 22 skipping to change at page 26, line 22
RFC 6553, 6554 and IPv6-in-IPv6", draft-robles-roll- RFC 6553, 6554 and IPv6-in-IPv6", draft-robles-roll-
useofrplinfo-02 (work in progress), October 2015. useofrplinfo-02 (work in progress), October 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.
[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 [RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
Internet of Things (IoT): Problem Statement", RFC 7554, Internet of Things (IoT): Problem Statement", RFC 7554,
DOI 10.17487/RFC7554, May 2015, DOI 10.17487/RFC7554, May 2015,
<http://www.rfc-editor.org/info/rfc7554>. <http://www.rfc-editor.org/info/rfc7554>.
Appendix A. Examples Appendix A. Examples
skipping to change at page 25, line 50 skipping to change at page 27, line 12
fragmentation process takes place per [RFC4944], and the fragment fragmentation process takes place per [RFC4944], and the fragment
headers must be placed in Page 0 before switching to Page 1: headers must be placed in Page 0 before switching to Page 1:
+- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+... +- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+...
|Frag type|Frag hdr |11110001| RPI- |IP-in-IP| LOWPAN-IPHC | ... |Frag type|Frag hdr |11110001| RPI- |IP-in-IP| LOWPAN-IPHC | ...
|RFC 4944 |RFC 4944 | Page 1 | 6LoRH | 6LoRH | | |RFC 4944 |RFC 4944 | Page 1 | 6LoRH | 6LoRH | |
+- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+... +- ... -+- ... -+-+ ... -+- ... +-+-+ ... -+-+-+-+-+-+-+-+-+-+...
<- RFC 6282 -> <- RFC 6282 ->
No RPL artifact No RPL artifact
+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
|Frag type|Frag hdr |
|RFC 4944 |RFC 4944 | Payload (cont)
+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
|Frag type|Frag hdr |
|RFC 4944 |RFC 4944 | Payload (cont)
+- ... -+- ... -+-+ ... -+-+ ... -+- ... +-+-+-+-+-+-+-+-+-+-+...
Figure 15: Example Compressed Packet with RPI. Figure 15: Example Compressed Packet with RPI.
In Storing Mode, if the packet stays within the RPL domain, then it In Storing Mode, if the packet stays within the RPL domain, then it
is possible to save the IP-in-IP encapsulation, in which case only is possible to save the IP-in-IP encapsulation, in which case only
the RPI is compressed with a 6LoRH, as illustrated in Figure 16 in the RPI is compressed with a 6LoRH, as illustrated in Figure 16 in
the case of a non-fragmented ICMP packet: the case of a non-fragmented ICMP packet:
+- ... -+-+- ... -+-+-+-+ ... -+-+-+-+ ... -+-+-+-+-+-+-+-+-+-+-+... +- ... -+-+- ... -+-+-+-+ ... -+-+-+-+ ... -+-+-+-+-+-+-+-+-+-+-+...
|11110001| RPI-6LoRH | NH = 0 | NH = 58 | ICMP message ... |11110001| RPI-6LoRH | NH = 0 | NH = 58 | ICMP message ...
|Page 1 | type 5 | 6LOWPAN-IPHC | (ICMP) | (no compression) |Page 1 | type 5 | 6LOWPAN-IPHC | (ICMP) | (no compression)
skipping to change at page 27, line 21 skipping to change at page 28, line 34
Figure 19: RPI inserted by the root in Storing Mode. Figure 19: RPI inserted by the root in Storing Mode.
A.2. Example Of Downward Packet In Non-Storing Mode A.2. Example Of Downward Packet In Non-Storing Mode
The example illustrated in Figure 20 is a classical packet in non- The example illustrated in Figure 20 is a classical packet in non-
Storing mode for a packet going down the DODAG following a source Storing mode for a packet going down the DODAG following a source
routed path from the root. Say that we have 4 forwarding hops to routed path from the root. Say that we have 4 forwarding hops to
reach a destination. In the non-compressed form, when the root reach a destination. In the non-compressed form, when the root
generates the packet, the last 3 hops are encoded in a Routing Header generates the packet, the last 3 hops are encoded in a Routing Header
type 3 (RH3) and the first hop is the destination of the packet. The type 3 (SRH) and the first hop is the destination of the packet. The
intermediate hops perform a swap and the hop count indicates the intermediate hops perform a swap and the hop count indicates the
current active hop [RFC2460], [RFC6554]. current active hop [RFC2460], [RFC6554].
When compressed with this specification, the 4 hops are encoded in When compressed with this specification, the 4 hops are encoded in
RH3-6LoRH when the root generates the packet, and the final SRH-6LoRH when the root generates the packet, and the final
destination is left in the LOWPAN-IPHC. There is no swap, and the destination is left in the LOWPAN-IPHC. There is no swap, and the
forwarding node that corresponds to the first entry effectively forwarding node that corresponds to the first entry effectively
consumes it when forwarding, which means that the size of the encoded consumes it when forwarding, which means that the size of the encoded
packet decreases and that the hop information is lost. packet decreases and that the hop information is lost.
If the last hop in a RH3-6LoRH is not the final destination then it If the last hop in a SRH-6LoRH is not the final destination then it
removes the RH3-6LoRH before forwarding. removes the SRH-6LoRH before forwarding.
In the particular example illustrated in Figure 20, all addresses in In the particular example illustrated in Figure 20, all addresses in
the DODAG are assigned from a same /112 prefix and the last 2 octets the DODAG are assigned from a same /112 prefix and the last 2 octets
encoding an identifier such as a IEEE 802.15.4 short address. In encoding an identifier such as a IEEE 802.15.4 short address. In
that case, all addresses can be compressed to 2 octets, using the that case, all addresses can be compressed to 2 octets, using the
root address as reference. There will be one RH3_6LoRH header, with, root address as reference. There will be one SRH_6LoRH header, with,
in this example, 3 compressed addresses: in this example, 3 compressed addresses:
+-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-... +-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-...
|11110001 |RH3-6LoRH | RPI-6LoRH | IP-in-IP | NH=1 |11110CPP| UDP | UDP |11110001 |SRH-6LoRH | RPI-6LoRH | IP-in-IP | NH=1 |11110CPP| UDP | UDP
|Page 1 |Type1 S=2 | | 6LoRH | IPHC | UDP | hdr |load |Page 1 |Type1 S=2 | | 6LoRH | IPHC | UDP | hdr |load
+-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-... +-+-+-+-+-+-+- ... +-+-+- ... -+-+-- ... -+-+- ... -+-+-+-+-+ ... +-...
<-8bytes-> <- RFC 6282 -> <-8bytes-> <- RFC 6282 ->
No RPL artifact No RPL artifact
Figure 20: Example Compressed Packet with RH3. Figure 20: Example Compressed Packet with SRH.
One may note that the RPI is provided. This is because the address One may note that the RPI is provided. This is because the address
of the root that is the source of the IP-in-IP header is elided and of the root that is the source of the IP-in-IP header is elided and
inferred from the InstanceID in the RPI. Once found from a local inferred from the RPLInstanceID in the RPI. Once found from a local
context, that address is used as Compression Reference to expand context, that address is used as Compression Reference to expand
addresses in the RH3-6LoRH. addresses in the SRH-6LoRH.
With the RPL specifications available at the time of writing this With the RPL specifications available at the time of writing this
draft, the root is the only node that may incorporate a RH3 in an IP draft, the root is the only node that may incorporate a SRH in an IP
packet. When the root forwards a packet that it did not generate, it packet. When the root forwards a packet that it did not generate, it
has to encapsulate the packet with IP-in-IP. has to encapsulate the packet with IP-in-IP.
But if the root generates the packet towards a node in its DODAG, But if the root generates the packet towards a node in its DODAG,
then it should avoid the extra IP-in-IP as illustrated in Figure 21: then it should avoid the extra IP-in-IP as illustrated in Figure 21:
+- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+... +- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+...
|11110001| RH3-6LoRH | NH=1 | 11110CPP | Compressed | UDP |11110001| SRH-6LoRH | NH=1 | 11110CPP | Compressed | UDP
|Page 1 | Type1 S=3 | LOWPAN-IPHC| LOWPAN-NHC| UDP header | Payload |Page 1 | Type1 S=3 | LOWPAN-IPHC| LOWPAN-NHC| UDP header | Payload
+- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+... +- ... -+-+-+ ... +-+-+-+ ... -+-+-+-+-+-+-+-++-+- ... -+-+-+-+-+...
<- RFC 6282 -> <- RFC 6282 ->
Figure 21: compressed RH3 4*2bytes entries sourced by root. Figure 21: compressed SRH 4*2bytes entries sourced by root.
Note: the RPI is not represented though RPL [RFC6550] generally Note: the RPI is not represented though RPL [RFC6550] generally
expects it. In this particular case, since the Compression Reference expects it. In this particular case, since the Compression Reference
for the RH3-6LoRH is the source address in the LOWPAN-IPHC, and the for the SRH-6LoRH is the source address in the LOWPAN-IPHC, and the
routing is strict along the source route path, the RPI does not routing is strict along the source route path, the RPI does not
appear to be absolutely necessary. appear to be absolutely necessary.
In Figure 21, all the nodes along the source route path share a same In Figure 21, all the nodes along the source route path share a same
/112 prefix. This is typical of IPv6 addresses derived from an /112 prefix. This is typical of IPv6 addresses derived from an
IEEE802.15.4 short address, as long as all the nodes share a same IEEE802.15.4 short address, as long as all the nodes share a same
PAN-ID. In that case, a type-1 RH3-6LoRH header can be used for PAN-ID. In that case, a type-1 SRH-6LoRH header can be used for
encoding. The IPv6 address of the root is taken as reference, and encoding. The IPv6 address of the root is taken as reference, and
only the last 2 octets of the address of the intermediate hops is only the last 2 octets of the address of the intermediate hops is
encoded. The Size of 3 indicates 4 hops, resulting in a RH3-6LoRH of encoded. The Size of 3 indicates 4 hops, resulting in a SRH-6LoRH of
10 bytes. 10 bytes.
A.3. Example of RH3-6LoRH life-cycle A.3. Example of SRH-6LoRH life-cycle
This section illustrates the operation specified in Section 5.5 of This section illustrates the operation specified in Section 5.6 of
forwarding a packet with a compressed RH3 along an A->B->C->D source forwarding a packet with a compressed SRH along an A->B->C->D source
route path. The operation of popping addresses is exemplified at route path. The operation of popping addresses is exemplified at
each hop. each hop.
Packet as received by node A Packet as received by node A
---------------------------- ----------------------------
Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA AAAA Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA AAAA
Type 1 RH3-6LoRH Size = 0 BBBB Type 1 SRH-6LoRH Size = 0 BBBB
Type 2 RH3-6LoRH Size = 1 CCCC CCCC Type 2 SRH-6LoRH Size = 1 CCCC CCCC
DDDD DDDD DDDD DDDD
Step 1 popping BBBB the first entry of the next RH3-6LoRH Step 1 popping BBBB the first entry of the next SRH-6LoRH
Step 2 next is if larger value (2 vs. 1) the RH3-6LoRH is removed Step 2 next is if larger value (2 vs. 1) the SRH-6LoRH is removed
Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA AAAA Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA AAAA
Type 2 RH3-6LoRH Size = 1 CCCC CCCC Type 2 SRH-6LoRH Size = 1 CCCC CCCC
DDDD DDDD DDDD DDDD
Step 3: recursion ended, coalescing BBBB with the first entry Step 3: recursion ended, coalescing BBBB with the first entry
Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA BBBB Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA BBBB
Step 4: routing based on next segment endpoint to B Step 4: routing based on next segment endpoint to B
Figure 22: Processing at Node A. Figure 22: Processing at Node A.
Packet as received by node B Packet as received by node B
---------------------------- ----------------------------
Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA BBBB Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA BBBB
Type 2 RH3-6LoRH Size = 1 CCCC CCCC Type 2 SRH-6LoRH Size = 1 CCCC CCCC
DDDD DDDD DDDD DDDD
Step 1 popping CCCC CCCC, the first entry of the next RH3-6LoRH Step 1 popping CCCC CCCC, the first entry of the next SRH-6LoRH
Step 2 removing the first entry and decrementing the Size (by 1) Step 2 removing the first entry and decrementing the Size (by 1)
Type 3 RH3-6LoRH Size = 0 AAAA AAAA AAAA BBBB Type 3 SRH-6LoRH Size = 0 AAAA AAAA AAAA BBBB
Type 2 RH3-6LoRH Size = 0 DDDD DDDD Type 2 SRH-6LoRH Size = 0 DDDD DDDD
Step 3: recursion ended, coalescing CCCC CCCC with the first entry Step 3: recursion ended, coalescing CCCC CCCC with the first entry
Type 3 RH3-6LoRH Size = 0 AAAA AAAA CCCC CCCC Type 3 SRH-6LoRH Size = 0 AAAA AAAA CCCC CCCC
Step 4: routing based on next segment endpoint to C Step 4: routing based on next segment endpoint to C
Figure 23: Processing at Node B. Figure 23: Processing at Node B.
Packet as received by node C Packet as received by node C
---------------------------- ----------------------------
Type 3 RH3-6LoRH Size = 0 AAAA AAAA CCCC CCCC Type 3 SRH-6LoRH Size = 0 AAAA AAAA CCCC CCCC
Type 2 RH3-6LoRH Size = 0 DDDD DDDD Type 2 SRH-6LoRH Size = 0 DDDD DDDD
Step 1 popping DDDD DDDD, the first entry of the next RH3-6LoRH Step 1 popping DDDD DDDD, the first entry of the next SRH-6LoRH
Step 2 the RH3-6LoRH is removed Step 2 the SRH-6LoRH is removed
Type 3 RH3-6LoRH Size = 0 AAAA AAAA CCCC CCCC Type 3 SRH-6LoRH Size = 0 AAAA AAAA CCCC CCCC
Step 3: recursion ended, coalescing DDDD DDDDD with the first entry Step 3: recursion ended, coalescing DDDD DDDDD with the first entry
Type 3 RH3-6LoRH Size = 0 AAAA AAAA DDDD DDDD Type 3 SRH-6LoRH Size = 0 AAAA AAAA DDDD DDDD
Step 4: routing based on next segment endpoint to D Step 4: routing based on next segment endpoint to D
Figure 24: Processing at Node C. Figure 24: Processing at Node C.
Packet as received by node D Packet as received by node D
---------------------------- ----------------------------
Type 3 RH3-6LoRH Size = 0 AAAA AAAA DDDD DDDD Type 3 SRH-6LoRH Size = 0 AAAA AAAA DDDD DDDD
Step 1 the RH3-6LoRH is removed. Step 1 the SRH-6LoRH is removed.
Step 2 no more header, routing based on inner IP header. Step 2 no more header, routing based on inner IP header.
Figure 25: Processing at Node D. Figure 25: Processing at Node D.
Authors' Addresses Authors' Addresses
Pascal Thubert (editor) Pascal Thubert (editor)
Cisco Systems Cisco Systems
Building D - Regus Building D - Regus
45 Allee des Ormes 45 Allee des Ormes
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