rfc9010v3.txt   rfc9010.txt 
Internet Engineering Task Force (IETF) P. Thubert, Ed. Internet Engineering Task Force (IETF) P. Thubert, Ed.
Request for Comments: 9010 Cisco Systems Request for Comments: 9010 Cisco Systems
Updates: 6550, 6775, 8505 M. Richardson Updates: 6550, 6775, 8505 M. Richardson
Category: Standards Track Sandelman Category: Standards Track Sandelman
ISSN: 2070-1721 March 2021 ISSN: 2070-1721 April 2021
Routing for RPL (Routing Protocol for Low-Power Routing for RPL (Routing Protocol for Low-Power
and Lossy Networks) Leaves and Lossy Networks) Leaves
Abstract Abstract
This specification provides a mechanism for a host that implements a This specification provides a mechanism for a host that implements a
routing-agnostic interface based on IPv6 over Low-Power Wireless routing-agnostic interface based on IPv6 over Low-Power Wireless
Personal Area Network (6LoWPAN) Neighbor Discovery to obtain Personal Area Network (6LoWPAN) Neighbor Discovery to obtain
reachability services across a network that leverages RFC 6550 for reachability services across a network that leverages RFC 6550 for
skipping to change at line 80 skipping to change at line 80
6.1. Updated RPL Target Option 6.1. Updated RPL Target Option
6.2. Additional Flag in the RPL DODAG Configuration Option 6.2. Additional Flag in the RPL DODAG Configuration Option
6.3. Updated RPL Status 6.3. Updated RPL Status
7. Enhancements to RFC 9009 7. Enhancements to RFC 9009
8. Enhancements to RFCs 6775 and 8505 8. Enhancements to RFCs 6775 and 8505
9. Protocol Operations for Unicast Addresses 9. Protocol Operations for Unicast Addresses
9.1. General Flow 9.1. General Flow
9.2. Detailed Operation 9.2. Detailed Operation
9.2.1. Perspective of the 6LN Acting as a RUL 9.2.1. Perspective of the 6LN Acting as a RUL
9.2.2. Perspective of the 6LR Acting as a Border Router 9.2.2. Perspective of the 6LR Acting as a Border Router
9.2.3. Perspective of the RPL Root 9.2.3. Perspective of the RPL DODAG Root
9.2.4. Perspective of the 6LBR 9.2.4. Perspective of the 6LBR
10. Protocol Operations for Multicast Addresses 10. Protocol Operations for Multicast Addresses
11. Security Considerations 11. Security Considerations
12. IANA Considerations 12. IANA Considerations
12.1. Fixing the Address Registration Option Flags 12.1. Fixing the Address Registration Option Flags
12.2. Resizing the ARO Status Values 12.2. Resizing the ARO Status Values
12.3. New RPL DODAG Configuration Option Flag 12.3. New RPL DODAG Configuration Option Flag
12.4. RPL Target Option Flags Registry 12.4. RPL Target Option Flags Registry
12.5. New Subregistry for RPL Non-Rejection Status Values 12.5. New Subregistry for RPL Non-Rejection Status Values
12.6. New Subregistry for RPL Rejection Status Values 12.6. New Subregistry for RPL Rejection Status Values
skipping to change at line 107 skipping to change at line 107
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, which is the most constrained resource of
all. Other design constraints, such as a limited memory capacity, all. Other design constraints, such as a limited memory capacity,
duty cycling of the LLN devices, and low-power lossy transmissions, duty cycling of the LLN devices, and low-power lossy transmissions,
derive from that primary concern. derive from that primary concern.
The IETF produced "RPL: IPv6 Routing Protocol for Low-Power and Lossy The IETF produced "RPL: IPv6 Routing Protocol for Low-Power and Lossy
Networks" [RFC6550] to provide IPv6 routing services [RFC8200] within Networks" [RFC6550] to provide routing services for IPv6 [RFC8200]
such constraints. RPL belongs to the class of distance-vector within such constraints. RPL belongs to the class of distance-vector
protocols -- which, compared to link-state protocols, limit the protocols -- which, compared to link-state protocols, limit the
amount of topological knowledge that needs to be installed and amount of topological knowledge that needs to be installed and
maintained in each node -- and does not require convergence to avoid maintained in each node -- and does not require convergence to avoid
micro-loops. micro-loops.
To save signaling and routing state in constrained networks, RPL To save signaling and routing state in constrained networks, RPL
allows a path stretch (see [RFC6687]), whereby routing is only allows a path stretch (see [RFC6687]), whereby routing is only
performed along a Destination-Oriented Directed Acyclic Graph (DODAG) performed along a Destination-Oriented Directed Acyclic Graph (DODAG)
that is optimized to reach a root node, as opposed to along the that is optimized to reach a root node, as opposed to along the
shortest path between two peers, whatever that would mean in a given shortest path between two peers, whatever that would mean in a given
LLN. This trades the quality of peer-to-peer (P2P) paths for a LLN. This trades the quality of peer-to-peer (P2P) paths for a
vastly reduced amount of control traffic and routing state that would vastly reduced amount of control traffic and routing state that would
be required to operate an any-to-any shortest-path protocol. be required to operate an any-to-any shortest-path protocol.
Additionally, broken routes may be fixed lazily and on demand, based Additionally, broken routes may be fixed lazily and on demand, based
on data-plane inconsistency discovery, which avoids wasting energy in on data-plane inconsistency discovery, which avoids wasting energy in
the proactive repair of unused paths. the proactive repair of unused paths.
For many of the nodes, though not all, the DODAG provides multiple For many of the nodes, though not all, the DODAG provides multiple
forwarding solutions towards the Root of the topology via so-called forwarding solutions towards the root of the topology via so-called
parents. RPL installs the routes proactively, but to adapt to fuzzy parents. RPL installs the routes proactively, but to adapt to fuzzy
connectivity -- whereby the physical topology cannot be expected to connectivity -- whereby the physical topology cannot be expected to
reach a stable state -- it uses a lazy route maintenance operation reach a stable state -- it uses a lazy route maintenance operation
that may only fix them reactively, upon actual traffic. The result that may only fix them reactively, upon actual traffic. The result
is that RPL provides reachability for most of the LLN nodes, most of is that RPL provides reachability for most of the LLN nodes, most of
the time, but may not converge in the classical sense. the time, but may not converge in the classical sense.
RPL can be deployed in conjunction with IPv6 Neighbor Discovery (ND) RPL can be deployed in conjunction with IPv6 Neighbor Discovery (ND)
[RFC4861] [RFC4862] and IPv6 over Low-Power Wireless Personal Area [RFC4861] [RFC4862] and IPv6 over Low-Power Wireless Personal Area
Network (6LoWPAN) ND [RFC6775] [RFC8505] to maintain reachability Network (6LoWPAN) ND [RFC6775] [RFC8505] to maintain reachability
skipping to change at line 176 skipping to change at line 176
leverage 6LoWPAN ND to obtain the routing services from the router. leverage 6LoWPAN ND to obtain the routing services from the router.
In that model, the RUL is also a 6LoWPAN Node (6LN) and the RPL-aware In that model, the RUL is also a 6LoWPAN Node (6LN) and the RPL-aware
router is also a 6LoWPAN Router (6LR). Using the 6LoWPAN ND Address router is also a 6LoWPAN Router (6LR). Using the 6LoWPAN ND Address
Registration mechanism, the RUL signals that the router must inject a Registration mechanism, the RUL signals that the router must inject a
host route for the Registered Address. host route for the Registered Address.
------+--------- ------+---------
| Internet | Internet
| |
+-----+ +-----+
| | <------------- 6LBR / RPL Root | | <------------- 6LBR / RPL DODAG Root
+-----+ ^ +-----+ ^
| | | |
o o o o | RPL o o o o | RPL
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 o o o o |
o o o o o o o o o | 6LoWPAN ND o o o o o o o o o | 6LoWPAN ND
o o o o o o | o o o o o o |
o o o o v o o o o v
o o o <------------- 6LR / RPL Border Router o o o <------------- 6LR / RPL Border Router
^ ^
| 6LoWPAN ND only | 6LoWPAN ND only
v v
u <------------- 6LN / RPL-Unaware Leaf u <------------- 6LN / RPL-Unaware Leaf
Figure 1: Injecting Routes on Behalf of RULs Figure 1: Injecting Routes on Behalf of RULs
The RPL Non-Storing mode mechanism is used to extend the routing The RPL Non-Storing mode mechanism is used to extend the routing
state with connectivity to the RULs even when the DODAG is operated state with connectivity to the RULs even when the DODAG is operated
in Storing mode. The unicast packet-forwarding operation by the 6LR in Storing mode. The unicast packet-forwarding operation by the 6LR
serving a RUL is described in Section 4.1 of [RFC9008]. serving a RUL is described in Section 4.1.1 of [RFC9008].
Examples of possible RULs include severely energy-constrained sensors Examples of possible RULs include severely energy-constrained sensors
such as window smash sensors (alarm system) and kinetically powered such as window smash sensors (alarm system) and kinetically powered
light switches. Other applications of this specification may include light switches. Other applications of this specification may include
a smart grid network that controls appliances -- such as washing a smart grid network that controls appliances -- such as washing
machines or the heating system -- in the home. Appliances may not machines or the heating system -- in the home. Appliances may not
participate in the RPL protocol operated in the smart grid network participate in the RPL protocol operated in the smart grid network
but can still interact with the smart grid for control and/or but can still interact with the smart grid for control and/or
metering. metering.
This specification can be deployed incrementally in a network that This specification can be deployed incrementally in a network that
implements [RFC9008]. Only the Root and the 6LRs that connect the implements [RFC9008]. Only the root and the 6LRs that connect the
RULs need to be upgraded. The RPL routers on the path will only see RULs need to be upgraded. The RPL routers on the path will only see
unicast IPv6 traffic between the Root and the 6LR. unicast IPv6 traffic between the root and the 6LR.
This document is organized as follows: This document is organized as follows:
* Sections 3 and 4 present in a non-normative fashion the salient * Sections 3 and 4 present in a non-normative fashion the salient
aspects of RPL and 6LoWPAN ND, respectively, that are leveraged in aspects of RPL and 6LoWPAN ND, respectively, that are leveraged in
this specification to provide connectivity to a 6LN acting as a this specification to provide connectivity to a 6LN acting as a
RUL across a RPL network. RUL across a RPL network.
* Section 5 lists the requirements that a RUL needs to match in * Section 5 lists the requirements that a RUL needs to match in
order to be served by a RPL router that complies with this order to be served by a RPL router that complies with this
specification. specification.
* Section 6 presents the changes made to [RFC6550]; a new behavior * Section 6 presents the changes made to [RFC6550]; a new behavior
is introduced whereby the 6LR advertises the 6LN's addresses in a is introduced whereby the 6LR advertises the 6LN's addresses in a
RPL Destination Advertisement Object (DAO) message based on the ND RPL Destination Advertisement Object (DAO) message based on the ND
registration by the 6LN, and the RPL root performs the Extended registration by the 6LN, and the RPL DODAG root performs the
Duplicate Address Request / Extended Duplicate Address Extended Duplicate Address Request / Extended Duplicate Address
Confirmation (EDAR/EDAC) exchange with the 6LoWPAN Border Router Confirmation (EDAR/EDAC) exchange with the 6LoWPAN Border Router
(6LBR) on behalf of the 6LR; modifications are introduced to some (6LBR) on behalf of the 6LR; modifications are introduced to some
RPL options and to the RPL Status to facilitate the integration of RPL options and to the RPL Status to facilitate the integration of
the protocols. the protocols.
* Section 7 presents the changes made to [RFC9009]; the use of the * Section 7 presents the changes made to [RFC9009]; the use of the
Destination Cleanup Object (DCO) message is extended to the Non- Destination Cleanup Object (DCO) message is extended to the Non-
Storing RPL Mode of Operation (MOP) to report asynchronous issues Storing RPL Mode of Operation (MOP) to report asynchronous issues
from the Root to the 6LR. from the root to the 6LR.
* Section 8 presents the changes made to [RFC6775] and [RFC8505]; * Section 8 presents the changes made to [RFC6775] and [RFC8505];
the range of the Address Registration Option / Extended Address the range of the Address Registration Option / Extended Address
Registration Option (ARO/EARO) Status values is reduced to 64 Registration Option (ARO/EARO) Status values is reduced to 64
values, and the remaining bits in the original status field are values, and the remaining bits in the original status field are
now reserved. now reserved.
* Sections 9 and 10 present the operation of this specification for * Sections 9 and 10 present the operation of this specification for
unicast and multicast flows, respectively, and Section 11 presents unicast and multicast flows, respectively, and Section 11 presents
associated security considerations. associated security considerations.
skipping to change at line 355 skipping to change at line 355
6LoWPAN ND: "Neighbor Discovery Optimization for IPv6 over Low-Power 6LoWPAN ND: "Neighbor Discovery Optimization for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)" [RFC6775], Wireless Personal Area Networks (6LoWPANs)" [RFC6775],
"Registration Extensions for IPv6 over Low-Power Wireless Personal "Registration Extensions for IPv6 over Low-Power Wireless Personal
Area Network (6LoWPAN) Neighbor Discovery" [RFC8505], Area Network (6LoWPAN) Neighbor Discovery" [RFC8505],
"Address-Protected Neighbor Discovery for Low-Power and Lossy "Address-Protected Neighbor Discovery for Low-Power and Lossy
Networks" [RFC8928], and "IPv6 Backbone Router" [RFC8929]. Networks" [RFC8928], and "IPv6 Backbone Router" [RFC8929].
3. RPL External Routes and Data-Plane Artifacts 3. RPL External Routes and Data-Plane Artifacts
RPL was initially designed to build stub networks whereby the only RPL was initially designed to build stub networks whereby the only
border router would be the RPL root (typically co-located with the border router would be the RPL DODAG root (typically co-located with
6LBR) and all the nodes in the stub would be RPL aware. But the 6LBR) and all the nodes in the stub would be RPL aware. But
[RFC6550] was also prepared to be extended for external routes [RFC6550] was also prepared to be extended for external routes
("targets" in RPL parlance), via the External ('E') flag in the ("targets" in RPL parlance), via the External ('E') flag in the
Transit Information Option (TIO). External targets provide the Transit Information Option (TIO). External targets provide the
ability to reach destinations that are outside the RPL domain and ability to reach destinations that are outside the RPL domain and
connected to the RPL domain via RPL border routers that are not the connected to the RPL domain via RPL border routers that are not the
Root. Section 4.1 of [RFC9008] provides a set of rules (summarized root. Section 4.1 of [RFC9008] provides a set of rules (summarized
below) that must be followed for routing packets to and from an below) that must be followed for routing packets to and from an
external destination. A RUL is a special case of an external target external destination. A RUL is a special case of an external target
that is also a host directly connected to the RPL domain. that is also a host directly connected to the RPL domain.
A 6LR that acts as a border router for external routes advertises A 6LR that acts as a border router for external routes advertises
them using Non-Storing mode DAO messages that are unicast directly to them using Non-Storing mode DAO messages that are unicast directly to
the Root, even if the DODAG is operated in Storing mode. Non-Storing the root, even if the DODAG is operated in Storing mode. Non-Storing
mode routes are not visible inside the RPL domain, and all packets mode routes are not visible inside the RPL domain, and all packets
are routed via the Root. The RPL root tunnels the data packets are routed via the root. The RPL DODAG root tunnels the data packets
directly to the 6LR that advertised the external route, which directly to the 6LR that advertised the external route, which
decapsulates and forwards the original (inner) packets. decapsulates and forwards the original (inner) packets.
The RPL Non-Storing MOP signaling and the associated IPv6-in-IPv6 The RPL Non-Storing MOP signaling and the associated IPv6-in-IPv6
encapsulated packets appear as normal traffic to the intermediate encapsulated packets appear as normal traffic to the intermediate
routers. Support of external routes only impacts the Root and the routers. Support of external routes only impacts the root and the
6LR. It can be operated with legacy intermediate routers and does 6LR. It can be operated with legacy intermediate routers and does
not add to the amount of state that must be maintained in those not add to the amount of state that must be maintained in those
routers. A RUL is an example of a destination that is reachable via routers. A RUL is an example of a destination that is reachable via
an external route that happens to also be a host route. an external route that happens to also be a host route.
The RPL data packets typically carry a Hop-by-Hop Header with a RPL The RPL data packets typically carry a Hop-by-Hop Header with a RPL
Option [RFC6553] that contains the RPI (the RPL Packet Information, Option [RFC6553] that contains the RPI (the RPL Packet Information,
as defined in Section 11.2 of [RFC6550]). Unless the RUL already as defined in Section 11.2 of [RFC6550]). Unless the RUL already
placed a RPL Option in the outer header chain, the packets from and placed a RPL Option in the outer header chain, the packets from and
to the RUL are encapsulated using an IPv6-in-IPv6 tunnel between the to the RUL are encapsulated using an IPv6-in-IPv6 tunnel between the
Root and the 6LR that serves the RUL (see Sections 7 and 8 of root and the 6LR that serves the RUL (see Sections 7 and 8 of
[RFC9008] for details). If the packet from the RUL has an RPI, the [RFC9008] for details). If the packet from the RUL has an RPI, the
6LR acting as a RPL border router rewrites the RPI to indicate the 6LR acting as a RPL border router rewrites the RPI to indicate the
selected RPL Instance and set the flags, but it does not need to selected RPL Instance and set the flags, but it does not need to
encapsulate the packet (see Section 9.2.2). encapsulate the packet (see Section 9.2.2).
In Non-Storing mode, packets going down the DODAG carry a Source In Non-Storing mode, packets going down the DODAG carry a Source
Routing Header (SRH). The IPv6-in-IPv6 encapsulation, the RPI, and Routing Header (SRH). The IPv6-in-IPv6 encapsulation, the RPI, and
the SRH are collectively called the "RPL artifacts" and can be the SRH are collectively called the "RPL artifacts" and can be
compressed using the method defined in [RFC8138]. Appendix A compressed using the method defined in [RFC8138]. Appendix A
presents an example compressed format for a packet forwarded by the presents an example compressed format for a packet forwarded by the
Root to a RUL in a Storing mode DODAG. root to a RUL in a Storing mode DODAG.
The inner packet that is forwarded to the RUL may carry some RPL The inner packet that is forwarded to the RUL may carry some RPL
artifacts, e.g., an RPI if the original packet was generated with it, artifacts, e.g., an RPI if the original packet was generated with it,
and an SRH in a Non-Storing mode DODAG. [RFC9008] expects the RUL to and an SRH in a Non-Storing mode DODAG. [RFC9008] expects the RUL to
support the basic IPv6 node requirements per [RFC8504] and, in support the basic IPv6 node requirements per [RFC8504] and, in
particular, the mandates in Sections 4.2 and 4.4 of [RFC8200]. As particular, the mandates in Sections 4.2 and 4.4 of [RFC8200]. As
such, the RUL is expected to ignore the RPL artifacts that may be such, the RUL is expected to ignore the RPL artifacts that may be
left over -- either an SRH whose Segments Left is zero or a RPL left over -- either an SRH whose Segments Left is zero or a RPL
Option in the Hop-by-Hop Header (which can be skipped when not Option in the Hop-by-Hop Header (which can be skipped when not
recognized; see Section 5.3 for details). recognized; see Section 5.3 for details).
skipping to change at line 524 skipping to change at line 524
protection against spoofing. protection against spoofing.
"Address-Protected Neighbor Discovery for Low-Power and Lossy "Address-Protected Neighbor Discovery for Low-Power and Lossy
Networks" [RFC8928] leverages the ROVR field as a cryptographic proof Networks" [RFC8928] leverages the ROVR field as a cryptographic proof
of ownership to prevent a rogue third party from registering an of ownership to prevent a rogue third party from registering an
address that is already owned. The use of the ROVR field enables the address that is already owned. The use of the ROVR field enables the
6LR to block traffic that is not sourced at an owned address. 6LR to block traffic that is not sourced at an owned address.
This specification does not address how the protection offered by This specification does not address how the protection offered by
[RFC8928] could be extended for use in RPL. On the other hand, it [RFC8928] could be extended for use in RPL. On the other hand, it
adds the ROVR to the DAO to build the proxied EDAR at the Root (see adds the ROVR to the DAO to build the proxied EDAR at the root (see
Section 6.1), which means that nodes that are aware of the host route Section 6.1), which means that nodes that are aware of the host route
are also aware of the ROVR associated to the Target Address. are also aware of the ROVR associated to the Target Address.
4.3. EDAR/EDAC per RFC 8505 4.3. EDAR/EDAC per RFC 8505
[RFC8505] updates the DAR/DAC messages to EDAR/EDAC messages to carry [RFC8505] updates the DAR/DAC messages to EDAR/EDAC messages to carry
the ROVR field. The EDAR/EDAC exchange takes place between the 6LR the ROVR field. The EDAR/EDAC exchange takes place between the 6LR
and the 6LBR. It is triggered by an NS(EARO) message from a 6LN to and the 6LBR. It is triggered by an NS(EARO) message from a 6LN to
create, refresh, and delete the corresponding state in the 6LBR. The create, refresh, and delete the corresponding state in the 6LBR. The
exchange is protected by the retry mechanism specified in exchange is protected by the retry mechanism specified in
Section 8.2.6 of [RFC6775], though in an LLN, a duration longer than Section 8.2.6 of [RFC6775], though in an LLN, a duration longer than
the default value of the RetransTimer (RETRANS_TIMER) [RFC4861] of 1 the default value of the RetransTimer (RETRANS_TIMER) [RFC4861] of 1
second may be necessary to cover the round-trip delay between the 6LR second may be necessary to cover the round-trip delay between the 6LR
and the 6LBR. and the 6LBR.
RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to RPL [RFC6550] specifies a periodic DAO from the 6LN all the way to
the Root that maintains the routing state in the RPL network for the the root that maintains the routing state in the RPL network for the
lifetime indicated by the source of the DAO. This means that for lifetime indicated by the source of the DAO. This means that for
each address, there are two keep-alive messages that traverse the each address, there are two keep-alive messages that traverse the
whole network: one to the Root and one to the 6LBR. whole network: one to the root and one to the 6LBR.
This specification avoids the periodic EDAR/EDAC exchange across the This specification avoids the periodic EDAR/EDAC exchange across the
LLN. The 6LR turns the periodic NS(EARO) from the RUL into a DAO LLN. The 6LR turns the periodic NS(EARO) from the RUL into a DAO
message to the Root on every refresh, but it only generates the EDAR message to the root on every refresh, but it only generates the EDAR
upon the first registration, for the purpose of DAD, which must be upon the first registration, for the purpose of DAD, which must be
verified before the address is injected in RPL. Upon the DAO verified before the address is injected in RPL. Upon the DAO
message, the Root proxies the EDAR exchange to refresh the state at message, the root proxies the EDAR exchange to refresh the state at
the 6LBR on behalf of the 6LR, as illustrated in Figure 8 in the 6LBR on behalf of the 6LR, as illustrated in Figure 8 in
Section 9.1. Section 9.1.
4.3.1. Capability Indication Option per RFC 7400 4.3.1. Capability Indication Option per RFC 7400
"6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power "6LoWPAN-GHC: Generic Header Compression for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the Wireless Personal Area Networks (6LoWPANs)" [RFC7400] defines the
6LoWPAN Capability Indication Option (6CIO), which enables a node to 6LoWPAN Capability Indication Option (6CIO), which enables a node to
expose its capabilities in Router Advertisement (RA) messages. expose its capabilities in Router Advertisement (RA) messages.
skipping to change at line 632 skipping to change at line 632
5.2. Support of IPv6 Encapsulation 5.2. Support of IPv6 Encapsulation
Section 4.1.1 of [RFC9008] defines the rules for signaling an Section 4.1.1 of [RFC9008] defines the rules for signaling an
external destination (e.g., a RUL) and tunneling to its attachment external destination (e.g., a RUL) and tunneling to its attachment
router (designated as a 6LR). In order to terminate the IPv6-in-IPv6 router (designated as a 6LR). In order to terminate the IPv6-in-IPv6
tunnel, the RUL, as an IPv6 host, would have to be capable of tunnel, the RUL, as an IPv6 host, would have to be capable of
decapsulating the tunneled packet and either drop the encapsulated decapsulating the tunneled packet and either drop the encapsulated
packet if it is not the final destination or pass it to the upper packet if it is not the final destination or pass it to the upper
layer for further processing. As indicated in Section 4.1 of layer for further processing. As indicated in Section 4.1 of
[RFC9008], this is not mandated by [RFC8504], and the IPv6-in-IPv6 [RFC9008], this is not mandated by [RFC8504], and the IPv6-in-IPv6
tunnel from the Root is terminated at the parent 6LR. It is thus not tunnel from the root is terminated at the parent 6LR. It is thus not
necessary for a RUL to support IPv6-in-IPv6 decapsulation. necessary for a RUL to support IPv6-in-IPv6 decapsulation.
5.3. Support of the Hop-by-Hop Header 5.3. Support of the Hop-by-Hop Header
A RUL is expected to process an Option Type in a Hop-by-Hop Header as A RUL is expected to process an Option Type in a Hop-by-Hop Header as
prescribed by Section 4.2 of [RFC8200]. An RPI with an Option Type prescribed by Section 4.2 of [RFC8200]. An RPI with an Option Type
of 0x23 [RFC9008] is thus skipped when not recognized. of 0x23 [RFC9008] is thus skipped when not recognized.
5.4. Support of the Routing Header 5.4. Support of the Routing Header
skipping to change at line 657 skipping to change at line 657
packet and sends an ICMP Parameter Problem message with Code 0 to the packet and sends an ICMP Parameter Problem message with Code 0 to the
packet's source address, pointing to the unrecognized Routing Type. packet's source address, pointing to the unrecognized Routing Type.
6. Enhancements to RFC 6550 6. Enhancements to RFC 6550
This document specifies a new behavior whereby a 6LR injects DAO This document specifies a new behavior whereby a 6LR injects DAO
messages for unicast addresses (see Section 9) and multicast messages for unicast addresses (see Section 9) and multicast
addresses (see Section 10) on behalf of leaves that are not aware of addresses (see Section 10) on behalf of leaves that are not aware of
RPL. The RUL addresses are exposed as external targets [RFC6550]. RPL. The RUL addresses are exposed as external targets [RFC6550].
Conforming to [RFC9008], IPv6-in-IPv6 encapsulation between the 6LR Conforming to [RFC9008], IPv6-in-IPv6 encapsulation between the 6LR
and the RPL root is used to carry the RPL artifacts and remove them and the RPL DODAG root is used to carry the RPL artifacts and remove
when forwarding outside the RPL domain, e.g., to a RUL. them when forwarding outside the RPL domain, e.g., to a RUL.
This document also synchronizes the liveness monitoring at the Root This document also synchronizes the liveness monitoring at the root
and the 6LBR. The same lifetime value is used for both, and a single and the 6LBR. The same lifetime value is used for both, and a single
keep-alive message, the RPL DAO, traverses the RPL network. Another keep-alive message, the RPL DAO, traverses the RPL network. Another
new behavior is introduced whereby the RPL root proxies the EDAR new behavior is introduced whereby the RPL DODAG root proxies the
message to the 6LBR on behalf of the 6LR (see Section 8), for any EDAR message to the 6LBR on behalf of the 6LR (see Section 8), for
leaf node that implements the 6LN functionality described in any leaf node that implements the 6LN functionality described in
[RFC8505]. [RFC8505].
Section 6.7.7 of [RFC6550] introduces the RPL Target option, which Section 6.7.7 of [RFC6550] introduces the RPL Target option, which
can be used in RPL control messages such as the DAO message to signal can be used in RPL control messages such as the DAO message to signal
a destination prefix. This document adds capabilities for a destination prefix. This document adds capabilities for
transporting the ROVR field (see Section 4.2.3) and the IPv6 address transporting the ROVR field (see Section 4.2.3) and the IPv6 address
of the prefix advertiser when the Target is a shorter prefix. Their of the prefix advertiser when the Target is a shorter prefix. Their
use is signaled by a new ROVR Size field being non-zero and a new use is signaled by a new ROVR Size field being non-zero and a new
"Advertiser address in Full (F)" flag set to 1, respectively; see "Advertiser address in Full (F)" flag set to 1, respectively; see
Section 6.1. Section 6.1.
skipping to change at line 687 skipping to change at line 687
This specification defines a new flag, "Root Proxies EDAR/EDAC (P)", This specification defines a new flag, "Root Proxies EDAR/EDAC (P)",
in the RPL DODAG Configuration option; see Section 6.2. in the RPL DODAG Configuration option; see Section 6.2.
Furthermore, this specification provides the ability to carry the Furthermore, this specification provides the ability to carry the
EARO Status defined for 6LoWPAN ND in RPL DAO and DCO messages, EARO Status defined for 6LoWPAN ND in RPL DAO and DCO messages,
embedded in a RPL Status; see Section 6.3. embedded in a RPL Status; see Section 6.3.
Section 12 of [RFC6550] details RPL support for multicast flows when Section 12 of [RFC6550] details RPL support for multicast flows when
the RPL Instance is operated with a MOP setting of 3 ("Storing Mode the RPL Instance is operated with a MOP setting of 3 ("Storing Mode
of Operation with multicast support"). This specification extends of Operation with multicast support"). This specification extends
the RPL root operation to proxy-relay the MLDv2 operation [RFC3810] the RPL DODAG root operation to proxy-relay the MLDv2 operation
between the RUL and the 6LR; see Section 10. [RFC3810] between the RUL and the 6LR; see Section 10.
6.1. Updated RPL Target Option 6.1. Updated RPL Target Option
This specification updates the RPL Target option to transport the This specification updates the RPL Target option to transport the
ROVR that was also defined for 6LoWPAN ND messages. This enables the ROVR that was also defined for 6LoWPAN ND messages. This enables the
RPL root to generate the proxied EDAR message to the 6LBR. RPL DODAG root to generate the proxied EDAR message to the 6LBR.
The Target Prefix of the RPL Target option is left (high bit) The Target Prefix of the RPL Target option is left (high bit)
justified and contains the advertised prefix; its size may be smaller justified and contains the advertised prefix; its size may be smaller
than 128 when it indicates a prefix route. The Prefix Length field than 128 when it indicates a prefix route. The Prefix Length field
signals the number of bits that correspond to the advertised prefix; signals the number of bits that correspond to the advertised prefix;
it is 128 for a host route or less in the case of a prefix route. it is 128 for a host route or less in the case of a prefix route.
This remains unchanged. This remains unchanged.
This specification defines the new 'F' flag. When it is set to 1, This specification defines the new 'F' flag. When it is set to 1,
the size of the Target Prefix field MUST be 128 bits and it MUST the size of the Target Prefix field MUST be 128 bits and it MUST
skipping to change at line 754 skipping to change at line 754
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Updated Target Option Figure 4: Updated Target Option
New fields: New fields:
F: 1-bit flag. Set to 1 to indicate that the Target Prefix field F: 1-bit flag. Set to 1 to indicate that the Target Prefix field
contains the complete (128-bit) IPv6 address of the advertising contains the complete (128-bit) IPv6 address of the advertising
node. node.
X: 1-bit flag. Set to 1 to request that the Root perform a proxy X: 1-bit flag. Set to 1 to request that the root perform a proxy
EDAR/EDAC exchange. EDAR/EDAC exchange.
The 'X' flag can only be set to 1 if the DODAG is operating in The 'X' flag can only be set to 1 if the DODAG is operating in
Non-Storing mode and if the Root sets the "Root Proxies EDAR/EDAC Non-Storing mode and if the root sets the "Root Proxies EDAR/EDAC
(P)" flag to 1 in the DODAG Configuration option; see (P)" flag to 1 in the DODAG Configuration option; see
Section 6.2. Section 6.2.
The 'X' flag can be set for host routes to RULs and RANs; it can The 'X' flag can be set for host routes to RULs and RANs; it can
also be set for internal prefix routes if the 'F' flag is set, also be set for internal prefix routes if the 'F' flag is set,
using the node's address in the Target Prefix field to form the using the node's address in the Target Prefix field to form the
EDAR, but it cannot be used otherwise. EDAR, but it cannot be used otherwise.
Flg (Flags): The 2 bits remaining unused in the Flags field are Flg (Flags): The 2 bits remaining unused in the Flags field are
reserved for flags. The field MUST be initialized to 0 by the reserved for flags. The field MUST be initialized to 0 by the
skipping to change at line 811 skipping to change at line 811
|4 bits | |4 bits |
Figure 5: DODAG Configuration Option (Partial View) Figure 5: DODAG Configuration Option (Partial View)
This specification defines a new flag, "Root Proxies EDAR/EDAC (P)". This specification defines a new flag, "Root Proxies EDAR/EDAC (P)".
The 'P' flag is encoded in bit position 1 of the reserved flags in The 'P' flag is encoded in bit position 1 of the reserved flags in
the DODAG Configuration option (counting from bit 0 as the most the DODAG Configuration option (counting from bit 0 as the most
significant bit), and it is set to 0 in legacy implementations as significant bit), and it is set to 0 in legacy implementations as
specified in Sections 20.14 and 6.7.6 of [RFC6550], respectively. specified in Sections 20.14 and 6.7.6 of [RFC6550], respectively.
The 'P' flag is set to 1 to indicate that the Root performs the proxy The 'P' flag is set to 1 to indicate that the root performs the proxy
operation, which implies that it supports this specification and the operation, which implies that it supports this specification and the
updated RPL Target option (see Section 6.1). updated RPL Target option (see Section 6.1).
Section 4.1.3 of [RFC9008] updates [RFC6550] to indicate that the Section 4.1.3 of [RFC9008] updates [RFC6550] to indicate that the
definition of the flags applies to MOP values from zero (0) to six definition of the flags applies to MOP values from zero (0) to six
(6) only. For a MOP value of 7, the implementation MUST assume that (6) only. For a MOP value of 7, the implementation MUST assume that
the Root performs the proxy operation. the root performs the proxy operation.
The RPL DODAG Configuration option is typically placed in a DODAG The RPL DODAG Configuration option is typically placed in a DODAG
Information Object (DIO) message. The DIO message propagates down Information Object (DIO) message. The DIO message propagates down
the DODAG to form and then maintain its structure. The DODAG the DODAG to form and then maintain its structure. The DODAG
Configuration option is copied unmodified from parents to children. Configuration option is copied unmodified from parents to children.
[RFC6550] states that "Nodes other than the DODAG root MUST NOT [RFC6550] states that "Nodes other than the DODAG root MUST NOT
modify this information when propagating the DODAG Configuration modify this information when propagating the DODAG Configuration
option." Therefore, a legacy parent propagates the 'P' flag as set option." Therefore, a legacy parent propagates the 'P' flag as set
by the Root, and when the 'P' flag is set to 1, it is transparently by the root, and when the 'P' flag is set to 1, it is transparently
flooded to all the nodes in the DODAG. flooded to all the nodes in the DODAG.
6.3. Updated RPL Status 6.3. Updated RPL Status
The RPL Status is defined in Section 6.5.1 of [RFC6550] for use in The RPL Status is defined in Section 6.5.1 of [RFC6550] for use in
the DAO-ACK message. Values are assigned as follows: the DAO-ACK message. Values are assigned as follows:
+---------+----------------------------------+ +---------+----------------------------------+
| Range | Meaning | | Range | Meaning |
+---------+----------------------------------+ +---------+----------------------------------+
skipping to change at line 886 skipping to change at line 886
Status Value: 6-bit unsigned integer. Status Value: 6-bit unsigned integer.
If the 'A' flag is set to 1, this field transports a value If the 'A' flag is set to 1, this field transports a value
defined for the 6LoWPAN ND EARO Status. defined for the 6LoWPAN ND EARO Status.
When the 'A' flag is set to 0, this field transports a Status When the 'A' flag is set to 0, this field transports a Status
value defined for RPL. value defined for RPL.
When building a DCO or a DAO-ACK message upon an IPv6 ND NA or an When building a DCO or a DAO-ACK message upon an IPv6 ND NA or an
EDAC message, the RPL root MUST copy the 6LoWPAN ND status code EDAC message, the RPL DODAG root MUST copy the 6LoWPAN ND status code
unchanged in the RPL Status Value field and set the 'A' flag to 1. unchanged in the RPL Status Value field and set the 'A' flag to 1.
The RPL root MUST set the 'U' flag to 1 for all rejection and unknown The RPL DODAG root MUST set the 'U' flag to 1 for all rejection and
status codes. The status codes in the 1-10 range [RFC8505] are all unknown status codes. The status codes in the 1-10 range [RFC8505]
considered rejections. are all considered rejections.
Reciprocally, upon a DCO or a DAO-ACK message from the RPL root with Reciprocally, upon a DCO or a DAO-ACK message from the RPL DODAG root
a RPL Status that has the 'A' flag set, the 6LR MUST copy the RPL with a RPL Status that has the 'A' flag set, the 6LR MUST copy the
Status value unchanged in the Status field of the EARO when RPL Status value unchanged in the Status field of the EARO when
generating an NA to the RUL. generating an NA to the RUL.
7. Enhancements to RFC 9009 7. Enhancements to RFC 9009
[RFC9009] defines the DCO message for RPL Storing mode only, with a [RFC9009] defines the DCO message for RPL Storing mode only, with a
link-local scope. All nodes in the RPL network are expected to link-local scope. All nodes in the RPL network are expected to
support the specification, since the message is processed hop by hop support the specification, since the message is processed hop by hop
along the path that is being cleaned up. along the path that is being cleaned up.
This specification extends the use of the DCO message to the Non- This specification extends the use of the DCO message to the Non-
Storing MOP, whereby the DCO is sent end to end by the Root directly Storing MOP, whereby the DCO is sent end to end by the root directly
to the RAN that injected the DAO message for the considered target. to the RAN that injected the DAO message for the considered target.
In that case, intermediate nodes do not need to support [RFC9009]; In that case, intermediate nodes do not need to support [RFC9009];
they forward the DCO message as a plain IPv6 packet between the Root they forward the DCO message as a plain IPv6 packet between the root
and the RAN. and the RAN.
In the case of a RUL, the 6LR that serves the RUL acts as the RAN In the case of a RUL, the 6LR that serves the RUL acts as the RAN
that receives the Non-Storing DCO. This specification leverages the that receives the Non-Storing DCO. This specification leverages the
Non-Storing DCO between the Root and the 6LR that serves as the Non-Storing DCO between the root and the 6LR that serves as the
attachment router for a RUL. A 6LR and a Root that support this attachment router for a RUL. A 6LR and a root that support this
specification MUST implement the Non-Storing DCO. specification MUST implement the Non-Storing DCO.
8. Enhancements to RFCs 6775 and 8505 8. Enhancements to RFCs 6775 and 8505
This document updates [RFC6775] and [RFC8505] to reduce the range of This document updates [RFC6775] and [RFC8505] to reduce the range of
the ARO/EARO Status values to 64 values. The two most significant the ARO/EARO Status values to 64 values. The two most significant
(leftmost) bits of the original ND Status field are now reserved; (leftmost) bits of the original ND Status field are now reserved;
they MUST be set to 0 by the sender and ignored by the receiver. they MUST be set to 0 by the sender and ignored by the receiver.
This document also updates the behavior of a 6LR acting as a RPL This document also updates the behavior of a 6LR acting as a RPL
router and of a 6LN acting as a RUL in the 6LoWPAN ND Address router and of a 6LN acting as a RUL in the 6LoWPAN ND Address
Registration as follows: Registration as follows:
* If the RPL root advertises the ability to proxy the EDAR/EDAC * If the RPL DODAG root advertises the ability to proxy the EDAR/
exchange to the 6LBR, the 6LR refrains from sending the keep-alive EDAC exchange to the 6LBR, the 6LR refrains from sending the keep-
EDAR message. If it is separated from the 6LBR, the Root alive EDAR message. If it is separated from the 6LBR, the root
regenerates the EDAR message to the 6LBR periodically, upon a DAO regenerates the EDAR message to the 6LBR periodically, upon a DAO
message that signals the liveliness of the address. message that signals the liveliness of the address.
* The use of the R flag is extended to the NA(EARO) to confirm * The use of the R flag is extended to the NA(EARO) to confirm
whether the route was installed. whether the route was installed.
9. Protocol Operations for Unicast Addresses 9. Protocol Operations for Unicast Addresses
The description below assumes that the Root sets the 'P' flag in the The description below assumes that the root sets the 'P' flag in the
DODAG Configuration option and performs the EDAR proxy operation DODAG Configuration option and performs the EDAR proxy operation
presented in Section 4.3. presented in Section 4.3.
If the 'P' flag is set to 0, the 6LR MUST generate the periodic EDAR If the 'P' flag is set to 0, the 6LR MUST generate the periodic EDAR
messages and process the returned status as specified in [RFC8505]. messages and process the returned status as specified in [RFC8505].
If the EDAC indicates success, the rest of the flow takes place as If the EDAC indicates success, the rest of the flow takes place as
presented but without the proxied EDAR/EDAC exchange. presented but without the proxied EDAR/EDAC exchange.
Section 9.1 provides an overview of the route injection in RPL, Section 9.1 provides an overview of the route injection in RPL,
whereas Section 9.2 offers more details from the perspective of the whereas Section 9.2 offers more details from the perspective of the
different nodes involved in the flow. different nodes involved in the flow.
9.1. General Flow 9.1. General Flow
This specification eliminates the need to exchange keep-alive EDAR This specification eliminates the need to exchange keep-alive EDAR
and EDAC messages all the way from a 6LN to the 6LBR across a RPL and EDAC messages all the way from a 6LN to the 6LBR across a RPL
mesh. Instead, the EDAR/EDAC exchange with the 6LBR is proxied by mesh. Instead, the EDAR/EDAC exchange with the 6LBR is proxied by
the RPL root upon the DAO message that refreshes the RPL routing the RPL DODAG root upon the DAO message that refreshes the RPL
state. The first EDAR upon a new Address Registration cannot be routing state. The first EDAR upon a new Address Registration cannot
proxied, though, as it is generated for the purpose of DAD, which be proxied, though, as it is generated for the purpose of DAD, which
must be verified before the address is injected in RPL. must be verified before the address is injected in RPL.
In a RPL network where the function is enabled, refreshing the state In a RPL network where the function is enabled, refreshing the state
in the 6LBR is the responsibility of the Root. Consequently, only in the 6LBR is the responsibility of the root. Consequently, only
addresses that are injected in RPL will be kept alive at the 6LBR by addresses that are injected in RPL will be kept alive at the 6LBR by
the RPL root. Since RULs are advertised using Non-Storing mode, the the RPL DODAG root. Since RULs are advertised using Non-Storing
DAO message flow and the keep-alive EDAR/EDAC can be nested within mode, the DAO message flow and the keep-alive EDAR/EDAC can be nested
the Address (re)Registration flow. Figure 7 illustrates that, for within the Address (re)Registration flow. Figure 7 illustrates that,
the first Address Registration, both the DAD and the keep-alive for the first Address Registration, both the DAD and the keep-alive
EDAR/EDAC exchanges happen in the same sequence. EDAR/EDAC exchanges happen in the same sequence.
6LN/RUL 6LR <6LR*> Root 6LBR 6LN/RUL 6LR <6LR*> Root 6LBR
|<---Using ND--->|<--Using RPL->|<-----Using ND---->| |<---Using ND--->|<--Using RPL->|<-----Using ND---->|
| |<-----------Using ND------------->| | |<-----------Using ND------------->|
| | | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|--------------->| | |--------------->| |
| | EDAR | | | EDAR |
| |--------------------------------->| | |--------------------------------->|
skipping to change at line 1031 skipping to change at line 1031
| | |------------------>| | | |------------------>|
| | | EDAC | | | | EDAC |
| | |<------------------| | | |<------------------|
| | DAO-ACK | | | | DAO-ACK | |
| |<-------------| | | |<-------------| |
| NA(EARO) | | | | NA(EARO) | | |
|<---------------| | | |<---------------| | |
Figure 8: Next RUL Registration Flow Figure 8: Next RUL Registration Flow
This is what causes the RPL root to refresh the state in the 6LBR, This is what causes the RPL DODAG root to refresh the state in the
using an EDAC message. In the case of an error in the proxied EDAR 6LBR, using an EDAC message. In the case of an error in the proxied
flow, the error is returned in the DAO-ACK using a RPL Status with EDAR flow, the error is returned in the DAO-ACK using a RPL Status
the 'A' flag set to 1, which embeds a 6LoWPAN Status value as with the 'A' flag set to 1, which embeds a 6LoWPAN Status value as
discussed in Section 6.3. discussed in Section 6.3.
The 6LR may receive a requested DAO-ACK after it received an The 6LR may receive a requested DAO-ACK after it received an
asynchronous Non-Storing DCO, but the non-zero status in the DCO asynchronous Non-Storing DCO, but the non-zero status in the DCO
supersedes a positive status in the DAO-ACK, regardless of the order supersedes a positive status in the DAO-ACK, regardless of the order
in which they are received. Upon the DAO-ACK -- or the DCO, if one in which they are received. Upon the DAO-ACK -- or the DCO, if one
arrives first -- the 6LR responds to the RUL with an NA(EARO). arrives first -- the 6LR responds to the RUL with an NA(EARO).
An issue may be detected later, e.g., the address moves to a An issue may be detected later, e.g., the address moves to a
different DODAG with the 6LBR attached to a different 6LoWPAN different DODAG with the 6LBR attached to a different 6LoWPAN
Backbone Router (6BBR); see Figure 5 in Section 3.3 of [RFC8929]. Backbone Router (6BBR); see Figure 5 in Section 3.3 of [RFC8929].
The 6BBR may send a negative ND Status, e.g., in an asynchronous The 6BBR may send a negative ND Status, e.g., in an asynchronous
NA(EARO) to the 6LBR. NA(EARO) to the 6LBR.
[RFC8929] expects that the 6LBR is co-located with the RPL root, but [RFC8929] expects that the 6LBR is co-located with the RPL DODAG
if not, the 6LBR MUST forward the status code to the originator of root, but if not, the 6LBR MUST forward the status code to the
the EDAR -- either the 6LR or the RPL root that proxies for it. The originator of the EDAR -- either the 6LR or the RPL DODAG root that
ND status code is mapped in a RPL Status value by the RPL root, and proxies for it. The ND status code is mapped in a RPL Status value
then back to an ND Status by the 6LR to the 6LN. Note that a legacy by the RPL DODAG root, and then back to an ND Status by the 6LR to
RAN that receives a Non-Storing DCO that it does not support will the 6LN. Note that a legacy RAN that receives a Non-Storing DCO that
ignore it silently, as specified in Section 6 of [RFC6550]. The it does not support will ignore it silently, as specified in
result is that it will remain unaware that it is no longer reachable Section 6 of [RFC6550]. The result is that it will remain unaware
until its next RPL exchange happens. This situation will be cleared that it is no longer reachable until its next RPL exchange happens.
upon the next Non-Storing DAO exchange if the error is returned in a This situation will be cleared upon the next Non-Storing DAO exchange
DAO-ACK. if the error is returned in a DAO-ACK.
Figure 9 illustrates this in the case where the 6LBR and the Root are Figure 9 illustrates this in the case where the 6LBR and the root are
not co-located, and the Root proxies the EDAR/EDAC flow. not co-located, and the root proxies the EDAR/EDAC flow.
6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR <-ND-> 6BBR 6LN/RUL <-ND-> 6LR <-RPL-> Root <-ND-> 6LBR <-ND-> 6BBR
| | | | | | | | | |
| | | | NA(EARO) | | | | | NA(EARO) |
| | | |<------------| | | | |<------------|
| | | EDAC | | | | | EDAC | |
| | |<-------------| | | | |<-------------| |
| | DCO | | | | | DCO | | |
| |<------------| | | | |<------------| | |
| NA(EARO) | | | | | NA(EARO) | | | |
|<-------------| | | | |<-------------| | | |
| | | | | | | | | |
Figure 9: Asynchronous Issue Figure 9: Asynchronous Issue
If the Root does not proxy, then the EDAC with a non-zero status If the root does not proxy, then the EDAC with a non-zero status
reaches the 6LR directly. In that case, the 6LR MUST clean up the reaches the 6LR directly. In that case, the 6LR MUST clean up the
route using a DAO with a Lifetime of 0, and it MUST propagate the route using a DAO with a Lifetime of 0, and it MUST propagate the
status back to the RUL in an NA(EARO) with the R flag set to 0. status back to the RUL in an NA(EARO) with the R flag set to 0.
The RUL may terminate the registration at any time by using a The RUL may terminate the registration at any time by using a
Registration Lifetime of 0. This specification requires that the RPL Registration Lifetime of 0. This specification requires that the RPL
Target option transport the ROVR. This way, the same flow as the Target option transport the ROVR. This way, the same flow as the
heartbeat flow is sufficient to inform the 6LBR using the Root as a heartbeat flow is sufficient to inform the 6LBR using the root as a
proxy, as illustrated in Figure 8. proxy, as illustrated in Figure 8.
All or any combination of the 6LR, the Root, and the 6LBR might be All or any combination of the 6LR, the root, and the 6LBR might be
collapsed in a single node. collapsed in a single node.
9.2. Detailed Operation 9.2. Detailed Operation
The following sections specify the behavior of (1) the 6LN acting as The following sections specify the behavior of (1) the 6LN acting as
a RUL, (2) the 6LR acting as a border router and serving the 6LN, a RUL, (2) the 6LR acting as a border router and serving the 6LN,
(3) the RPL root, and (4) the 6LBR in the control flows that enable (3) the RPL DODAG root, and (4) the 6LBR in the control flows that
RPL routing back to the RUL, respectively. enable RPL routing back to the RUL, respectively.
9.2.1. Perspective of the 6LN Acting as a RUL 9.2.1. Perspective of the 6LN Acting as a RUL
This specification builds on the operation of a 6LoWPAN ND-compliant This specification builds on the operation of a 6LoWPAN ND-compliant
6LN/RUL, which is expected to operate as follows: 6LN/RUL, which is expected to operate as follows:
1. The 6LN selects a 6LR that provides reachability services for a 1. The 6LN selects a 6LR that provides reachability services for a
RUL. This is signaled by a 6CIO in the RA messages with the L, RUL. This is signaled by a 6CIO in the RA messages with the L,
P, and E flags set to 1 as prescribed by [RFC8505]. P, and E flags set to 1 as prescribed by [RFC8505].
skipping to change at line 1196 skipping to change at line 1196
If the R flag is set to 1 in the NS(EARO), the 6LR SHOULD inject the If the R flag is set to 1 in the NS(EARO), the 6LR SHOULD inject the
host route in RPL, unless this is barred for other reasons, such as host route in RPL, unless this is barred for other reasons, such as
the saturation of the RPL parents. The 6LR MUST use RPL Non-Storing the saturation of the RPL parents. The 6LR MUST use RPL Non-Storing
mode signaling and the updated Target option (see Section 6.1). To mode signaling and the updated Target option (see Section 6.1). To
avoid a redundant EDAR/EDAC flow to the 6LBR, the 6LR SHOULD refrain avoid a redundant EDAR/EDAC flow to the 6LBR, the 6LR SHOULD refrain
from setting the 'X' flag. The 6LR MUST request a DAO-ACK by setting from setting the 'X' flag. The 6LR MUST request a DAO-ACK by setting
the 'K' flag in the DAO message. Successfully injecting the route to the 'K' flag in the DAO message. Successfully injecting the route to
the RUL's address will be indicated via the 'U' flag set to 0 in the the RUL's address will be indicated via the 'U' flag set to 0 in the
RPL Status of the DAO-ACK message. RPL Status of the DAO-ACK message.
For the registration refreshes, if the RPL root sets the 'P' flag in For the registration refreshes, if the RPL DODAG root sets the 'P'
the DODAG Configuration option to 1, then the 6LR MUST refrain from flag in the DODAG Configuration option to 1, then the 6LR MUST
sending the keep-alive EDAR; instead, it MUST set the 'X' flag to 1 refrain from sending the keep-alive EDAR; instead, it MUST set the
in the Target option of the DAO messages, to request that the Root 'X' flag to 1 in the Target option of the DAO messages, to request
proxy the keep-alive EDAR/EDAC exchange with the 6LBR (see that the root proxy the keep-alive EDAR/EDAC exchange with the 6LBR
Section 6); if the 'P' flag is set to 0, then the 6LR MUST set the (see Section 6); if the 'P' flag is set to 0, then the 6LR MUST set
'X' flag to 0 and handle the EDAR/EDAC flow itself. the 'X' flag to 0 and handle the EDAR/EDAC flow itself.
The Opaque field in the EARO provides a means to signal which RPL The Opaque field in the EARO provides a means to signal which RPL
Instance is to be used for the DAO advertisements and the forwarding Instance is to be used for the DAO advertisements and the forwarding
of packets sourced at the Registered Address when there is no RPI in of packets sourced at the Registered Address when there is no RPI in
the packet. the packet.
As described in [RFC8505], if the "I" field is 0, then the Opaque As described in [RFC8505], if the "I" field is 0, then the Opaque
field is expected to carry the RPLInstanceID suggested by the 6LN; field is expected to carry the RPLInstanceID suggested by the 6LN;
otherwise, there is no suggested RPL Instance. If the 6LR otherwise, there is no suggested RPL Instance. If the 6LR
participates in the suggested RPL Instance, then the 6LR MUST use participates in the suggested RPL Instance, then the 6LR MUST use
skipping to change at line 1247 skipping to change at line 1247
4. The Path Lifetime in the TIO is computed from the Registration 4. The Path Lifetime in the TIO is computed from the Registration
Lifetime in the EARO. This operation converts seconds to the Lifetime in the EARO. This operation converts seconds to the
Lifetime Units used in the RPL operation. This creates the Lifetime Units used in the RPL operation. This creates the
deployment constraint that the Lifetime Unit is reasonably deployment constraint that the Lifetime Unit is reasonably
compatible with the expression of the Registration Lifetime; compatible with the expression of the Registration Lifetime;
e.g., a Lifetime Unit of 0x4000 maps the most significant byte of e.g., a Lifetime Unit of 0x4000 maps the most significant byte of
the Registration Lifetime to the Path Lifetime. the Registration Lifetime to the Path Lifetime.
In that operation, the Path Lifetime must be set to ensure that In that operation, the Path Lifetime must be set to ensure that
the path has a longer lifetime than the registration and also the path has a longer lifetime than the registration and also
covers the round-trip time to the Root. covers the round-trip time to the root.
Note that if the Registration Lifetime is 0, then the Path Note that if the Registration Lifetime is 0, then the Path
Lifetime is also 0 and the DAO message becomes a No-Path DAO, Lifetime is also 0 and the DAO message becomes a No-Path DAO,
which cleans up the routes down to the RUL's address; this also which cleans up the routes down to the RUL's address; this also
causes the Root as a proxy to send an EDAR message to the 6LBR causes the root as a proxy to send an EDAR message to the 6LBR
with a Lifetime of 0. with a Lifetime of 0.
5. The Path Sequence in the TIO is set to the TID value found in the 5. The Path Sequence in the TIO is set to the TID value found in the
EARO. EARO.
Upon receiving or timing out the DAO-ACK after an implementation- Upon receiving or timing out the DAO-ACK after an implementation-
specific number of retries, the 6LR MUST send the corresponding specific number of retries, the 6LR MUST send the corresponding
NA(EARO) to the RUL. Upon receiving an asynchronous DCO message, it NA(EARO) to the RUL. Upon receiving an asynchronous DCO message, it
MUST send an asynchronous NA(EARO) to the RUL immediately but still MUST send an asynchronous NA(EARO) to the RUL immediately but still
be capable of processing the DAO-ACK if one is pending. be capable of processing the DAO-ACK if one is pending.
skipping to change at line 1373 skipping to change at line 1373
NS(EARO) with the R flag set to 1 the 6LR was injecting the host NS(EARO) with the R flag set to 1 the 6LR was injecting the host
route to the Registered Address in RPL using DAO messages, then the route to the Registered Address in RPL using DAO messages, then the
6LR MUST invalidate the host route in RPL using a DAO with a Path 6LR MUST invalidate the host route in RPL using a DAO with a Path
Lifetime of 0. It is up to the registering 6LN to maintain the Lifetime of 0. It is up to the registering 6LN to maintain the
corresponding route from then on, by either (1) keeping it active via corresponding route from then on, by either (1) keeping it active via
a different 6LR or (2) acting as a RAN and managing its own a different 6LR or (2) acting as a RAN and managing its own
reachability. reachability.
When forwarding a packet from the RUL into the RPL domain, if the When forwarding a packet from the RUL into the RPL domain, if the
packet does not have an RPI, the 6LR MUST encapsulate the packet to packet does not have an RPI, the 6LR MUST encapsulate the packet to
the Root and add an RPI. If there is an RPI in the packet, the 6LR the root and add an RPI. If there is an RPI in the packet, the 6LR
MUST rewrite the RPI, but it does not need to encapsulate. MUST rewrite the RPI, but it does not need to encapsulate.
9.2.3. Perspective of the RPL Root 9.2.3. Perspective of the RPL DODAG Root
A RPL root MUST set the 'P' flag to 1 in the RPL DODAG Configuration A RPL DODAG root MUST set the 'P' flag to 1 in the RPL DODAG
option of the DIO messages that it generates (see Section 6) to Configuration option of the DIO messages that it generates (see
signal that it proxies the EDAR/EDAC exchange and supports the Section 6) to signal that it proxies the EDAR/EDAC exchange and
updated RPL Target option. supports the updated RPL Target option.
Upon reception of a DAO message, for each updated RPL Target option Upon reception of a DAO message, for each updated RPL Target option
(see Section 6.1) with the 'X' flag set to 1, the Root MUST notify (see Section 6.1) with the 'X' flag set to 1, the root MUST notify
the 6LBR by using a proxied EDAR/EDAC exchange; if the RPL root and the 6LBR by using a proxied EDAR/EDAC exchange; if the RPL DODAG root
the 6LBR are integrated, an internal API can be used instead. and the 6LBR are integrated, an internal API can be used instead.
The EDAR message MUST be constructed as follows: The EDAR message MUST be constructed as follows:
1. The target IPv6 address from the RPL Target option is placed in 1. The target IPv6 address from the RPL Target option is placed in
the Registered Address field of the EDAR message; the Registered Address field of the EDAR message;
2. The Registration Lifetime is adapted from the Path Lifetime in 2. The Registration Lifetime is adapted from the Path Lifetime in
the TIO by converting the Lifetime Units used in RPL into units the TIO by converting the Lifetime Units used in RPL into units
of 60 seconds used in the 6LoWPAN ND messages; of 60 seconds used in the 6LoWPAN ND messages;
3. The TID value is set to the Path Sequence in the TIO and 3. The TID value is set to the Path Sequence in the TIO and
indicated with an ICMP code of 1 in the EDAR message; indicated with an ICMP code of 1 in the EDAR message;
4. The ROVR in the RPL Target option is copied as is in the EDAR, 4. The ROVR in the RPL Target option is copied as is in the EDAR,
and the ICMP Code Suffix is set to the appropriate value as shown and the ICMP Code Suffix is set to the appropriate value as shown
in Table 4 of [RFC8505], depending on the size of the ROVR field. in Table 4 of [RFC8505], depending on the size of the ROVR field.
Upon receiving an EDAC message from the 6LBR, if a DAO is pending, Upon receiving an EDAC message from the 6LBR, if a DAO is pending,
then the Root MUST send a DAO-ACK back to the 6LR. Otherwise, if the then the root MUST send a DAO-ACK back to the 6LR. Otherwise, if the
status in the EDAC message is not "Success", then it MUST send an status in the EDAC message is not "Success", then it MUST send an
asynchronous DCO to the 6LR. asynchronous DCO to the 6LR.
In either case, the EDAC Status is embedded in the RPL Status with In either case, the EDAC Status is embedded in the RPL Status with
the 'A' flag set to 1. the 'A' flag set to 1.
The proxied EDAR/EDAC exchange MUST be protected with a timer whose The proxied EDAR/EDAC exchange MUST be protected with a timer whose
appropriate duration and number of retries (1) are implementation appropriate duration and number of retries (1) are implementation
dependent and (2) SHOULD be configurable, since the Root and the 6LBR dependent and (2) SHOULD be configurable, since the root and the 6LBR
are typically nodes with a higher capacity and manageability than are typically nodes with a higher capacity and manageability than
6LRs. Upon timing out, the Root MUST send an error back to the 6LR 6LRs. Upon timing out, the root MUST send an error back to the 6LR
as above, using either a DAO-ACK or a DCO, as appropriate, with the as above, using either a DAO-ACK or a DCO, as appropriate, with the
'A' and 'U' flags set to 1 in the RPL Status, and a RPL Status value 'A' and 'U' flags set to 1 in the RPL Status, and a RPL Status value
of "6LBR Registry Saturated" [RFC8505]. of "6LBR Registry Saturated" [RFC8505].
9.2.4. Perspective of the 6LBR 9.2.4. Perspective of the 6LBR
The 6LBR is unaware that the RPL root is not the new attachment 6LR The 6LBR is unaware that the RPL DODAG root is not the new attachment
of the RUL, so it is not impacted by this specification. 6LR of the RUL, so it is not impacted by this specification.
Upon reception of an EDAR message, the 6LBR behaves as prescribed by Upon reception of an EDAR message, the 6LBR behaves as prescribed by
[RFC8505] and returns an EDAC message to the sender. [RFC8505] and returns an EDAC message to the sender.
10. Protocol Operations for Multicast Addresses 10. Protocol Operations for Multicast Addresses
Section 12 of [RFC6550] details RPL support for multicast flows. Section 12 of [RFC6550] details RPL support for multicast flows.
This support is activated by setting the MOP value to 3 ("Storing This support is activated by setting the MOP value to 3 ("Storing
Mode of Operation with multicast support") in the DIO messages that Mode of Operation with multicast support") in the DIO messages that
form the DODAG. This section also applies if and only if the MOP of form the DODAG. This section also applies if and only if the MOP of
skipping to change at line 1480 skipping to change at line 1480
This specification does not change MLD but will operate more This specification does not change MLD but will operate more
efficiently if the asynchronous messages for unsolicited Report and efficiently if the asynchronous messages for unsolicited Report and
Done are sent by the 6LN as Layer 2 unicast to the 6LR, particularly Done are sent by the 6LN as Layer 2 unicast to the 6LR, particularly
on wireless. on wireless.
The 6LR acts as a generic MLD querier and generates a DAO with the The 6LR acts as a generic MLD querier and generates a DAO with the
multicast address as the Target Prefix as described in Section 12 of multicast address as the Target Prefix as described in Section 12 of
[RFC6550]. As for the unicast host routes, the Path Lifetime [RFC6550]. As for the unicast host routes, the Path Lifetime
associated to the Target is mapped from the Query Interval and is set associated to the Target is mapped from the Query Interval and is set
to be larger, to account for variable propagation delays to the Root. to be larger, to account for variable propagation delays to the root.
The Root proxies the MLD exchange as a listener with the 6LBR acting The root proxies the MLD exchange as a listener with the 6LBR acting
as the querier, so as to get packets from a source external to the as the querier, so as to get packets from a source external to the
RPL domain. RPL domain.
Upon a DAO with a Target option for a multicast address, the RPL root Upon a DAO with a Target option for a multicast address, the RPL
checks to see if it is already registered as a listener for that DODAG root checks to see if it is already registered as a listener
address, and if not, it performs its own unsolicited Report for the for that address, and if not, it performs its own unsolicited Report
multicast address as described in Section 6.1 of [RFC3810]. The for the multicast address as described in Section 6.1 of [RFC3810].
Report is source independent, so there is no source address listed. The Report is source independent, so there is no source address
listed.
The equivalent of the registration refresh is pulled periodically by The equivalent of the registration refresh is pulled periodically by
the 6LR acting as the querier. Upon the timing out of the Query the 6LR acting as the querier. Upon the timing out of the Query
Interval, the 6LR sends a Multicast Address Specific Query to each of Interval, the 6LR sends a Multicast Address Specific Query to each of
its listeners, for each multicast address. The listeners respond its listeners, for each multicast address. The listeners respond
with a Report. Based on the Reports, the 6LR maintains the with a Report. Based on the Reports, the 6LR maintains the
aggregated list of all the multicast addresses for which there is a aggregated list of all the multicast addresses for which there is a
listener and advertises them using DAO messages as specified in listener and advertises them using DAO messages as specified in
Section 12 of [RFC6550]. Optionally, the 6LR MAY send a General Section 12 of [RFC6550]. Optionally, the 6LR MAY send a General
Query, where the Multicast Address field is set to 0. In that case, Query, where the Multicast Address field is set to 0. In that case,
the multicast packet is passed as a Layer 2 unicast to each of the the multicast packet is passed as a Layer 2 unicast to each of the
interested children. interested children.
Upon a Report, the 6LR generates a DAO with as many Target options as Upon a Report, the 6LR generates a DAO with as many Target options as
there are Multicast Address Records in the Report message, copying there are Multicast Address Records in the Report message, copying
the Multicast Address field in the Target Prefix of the RPL Target the Multicast Address field in the Target Prefix of the RPL Target
option. The DAO message is a Storing mode DAO, passed to a selection option. The DAO message is a Storing mode DAO, passed to a selection
of the 6LR's parents. of the 6LR's parents.
Asynchronously to this, a similar procedure happens between the Root Asynchronously to this, a similar procedure happens between the root
and a router, such as the 6LBR, that serves multicast flows on the and a router, such as the 6LBR, that serves multicast flows on the
link where the Root is located. Again, the Query and Report messages link where the root is located. Again, the Query and Report messages
are source independent. The Root lists exactly once each multicast are source independent. The root lists exactly once each multicast
address for which it has at least one active multicast DAO state, address for which it has at least one active multicast DAO state,
copying the multicast address in the DAO state in the Multicast copying the multicast address in the DAO state in the Multicast
Address field of the Multicast Address Records in the Report message. Address field of the Multicast Address Records in the Report message.
This is illustrated in Figure 12: This is illustrated in Figure 12:
6LN/RUL 6LR Root 6LBR 6LN/RUL 6LR Root 6LBR
| | | | | | | |
| Query | | | | Query | | |
|<-------------------| | | |<-------------------| | |
skipping to change at line 1537 skipping to change at line 1538
| | DAO-ACK | | | | DAO-ACK | |
| |<--------------| | | |<--------------| |
| | | Query | | | | Query |
| | |<-------------------| | | |<-------------------|
| | | Report | | | | Report |
| | |------------------->| | | |------------------->|
| | | | | | | |
Figure 12: Next Registration Flow Figure 12: Next Registration Flow
Note that all or any combination of the 6LR, the Root, and the 6LBR Note that all or any combination of the 6LR, the root, and the 6LBR
might be collapsed in a single node, in which case the flow above might be collapsed in a single node, in which case the flow above
happens internally, and possibly through internal API calls as happens internally, and possibly through internal API calls as
opposed to messaging. opposed to messaging.
11. Security Considerations 11. Security Considerations
It is worth noting that with [RFC6550], every node in the LLN is RPL It is worth noting that with [RFC6550], every node in the LLN is RPL
aware and can inject any RPL-based attack in the network. This aware and can inject any RPL-based attack in the network. This
specification improves this situation by isolating edge nodes that specification improves this situation by isolating edge nodes that
can only interact with the RPL routers using 6LoWPAN ND, meaning that can only interact with the RPL routers using 6LoWPAN ND, meaning that
skipping to change at line 1587 skipping to change at line 1588
Address and can be used to provide proof of ownership of the Address and can be used to provide proof of ownership of the
Registered Addresses. Once an address is registered with the Registered Addresses. Once an address is registered with the
Crypto-ID and proof of ownership is provided, only the owner of that Crypto-ID and proof of ownership is provided, only the owner of that
address can modify the registration information, thereby enforcing address can modify the registration information, thereby enforcing
SAVI. [RFC8928] reduces even further the attack perimeter that is SAVI. [RFC8928] reduces even further the attack perimeter that is
available to the edge nodes, and its use is suggested in this available to the edge nodes, and its use is suggested in this
specification. specification.
Additionally, the trust model could include role validation (e.g., Additionally, the trust model could include role validation (e.g.,
using role-based authorization) to ensure that the node that claims using role-based authorization) to ensure that the node that claims
to be a 6LBR or a RPL root is entitled to do so. to be a 6LBR or a RPL DODAG root is entitled to do so.
The Opaque field in the EARO enables the RUL to suggest a The Opaque field in the EARO enables the RUL to suggest a
RPLInstanceID where its traffic is placed. It is also possible for RPLInstanceID where its traffic is placed. It is also possible for
an attacker RUL to include an RPI in the packet. This opens the door an attacker RUL to include an RPI in the packet. This opens the door
to attacks where a RPL Instance would be reserved for critical to attacks where a RPL Instance would be reserved for critical
traffic, e.g., with a specific bandwidth reservation, that the traffic, e.g., with a specific bandwidth reservation, that the
additional traffic generated by a rogue may disrupt. The attack may additional traffic generated by a rogue may disrupt. The attack may
be alleviated by traditional access control and traffic-shaping be alleviated by traditional access control and traffic-shaping
mechanisms where the 6LR controls the incoming traffic from the 6LN. mechanisms where the 6LR controls the incoming traffic from the 6LN.
More importantly, the 6LR is the node that injects the traffic in the More importantly, the 6LR is the node that injects the traffic in the
RPL domain, so it has the final word on which RPL Instance is to be RPL domain, so it has the final word on which RPL Instance is to be
used for the traffic coming from the RUL, per its own policy. In used for the traffic coming from the RUL, per its own policy. In
particular, a policy can override the formal language that forces the particular, a policy can override the formal language that forces the
use of the Opaque field or the rewriting of the RPI provided by the use of the Opaque field or the rewriting of the RPI provided by the
RUL, in a situation where the network administrator finds it RUL, in a situation where the network administrator finds it
relevant. relevant.
At the time of this writing, RPL does not have a route ownership At the time of this writing, RPL does not have a route ownership
validation model whereby it is possible to validate the origin of an validation model whereby it is possible to validate the origin of an
address that is injected in a DAO. This specification makes a first address that is injected in a DAO. This specification makes a first
step in that direction by allowing the Root to challenge the RUL via step in that direction by allowing the root to challenge the RUL via
the 6LR that serves it. the 6LR that serves it.
Section 6.1 indicates that when the length of the ROVR field is Section 6.1 indicates that when the length of the ROVR field is
unknown, the RPL Target option must be passed on as received in RPL unknown, the RPL Target option must be passed on as received in RPL
Storing mode. This creates a possible opening for using DAO messages Storing mode. This creates a possible opening for using DAO messages
as a covert channel. Note that DAO messages are rare, and overusing as a covert channel. Note that DAO messages are rare, and overusing
that channel could be detected. An implementation SHOULD notify the that channel could be detected. An implementation SHOULD notify the
network management system when a RPL Target option is received with network management system when a RPL Target option is received with
an unknown ROVR field size, to ensure that the network administrator an unknown ROVR field size, to ensure that the network administrator
is aware of the situation. is aware of the situation.
skipping to change at line 1804 skipping to change at line 1805
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
[RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik, [RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik,
"Address-Protected Neighbor Discovery for Low-Power and "Address-Protected Neighbor Discovery for Low-Power and
Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November
2020, <https://www.rfc-editor.org/info/rfc8928>. 2020, <https://www.rfc-editor.org/info/rfc8928>.
[RFC9008] Robles, M.I., Richardson, M., and P. Thubert, "Using RPI [RFC9008] Robles, M.I., Richardson, M., and P. Thubert, "Using RPI
Option Type, Routing Header for Source Routes, and IPv6- Option Type, Routing Header for Source Routes, and IPv6-
in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008, in-IPv6 Encapsulation in the RPL Data Plane", RFC 9008,
DOI 10.17487/RFC9008, March 2021, DOI 10.17487/RFC9008, April 2021,
<https://www.rfc-editor.org/info/rfc9008>. <https://www.rfc-editor.org/info/rfc9008>.
[RFC9009] Jadhav, R., Ed., Thubert, P., Sahoo, R., and Z. Cao, [RFC9009] Jadhav, R., Ed., Thubert, P., Sahoo, R., and Z. Cao,
"Efficient Route Invalidation", RFC 9009, "Efficient Route Invalidation", RFC 9009,
DOI 10.17487/RFC9009, March 2021, DOI 10.17487/RFC9009, April 2021,
<https://www.rfc-editor.org/info/rfc9009>. <https://www.rfc-editor.org/info/rfc9009>.
13.2. Informative References 13.2. Informative References
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007, DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>. <https://www.rfc-editor.org/info/rfc4862>.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
skipping to change at line 1893 skipping to change at line 1894
RFC 8415, DOI 10.17487/RFC8415, November 2018, RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>. <https://www.rfc-editor.org/info/rfc8415>.
[RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli, [RFC8929] Thubert, P., Ed., Perkins, C.E., and E. Levy-Abegnoli,
"IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929, "IPv6 Backbone Router", RFC 8929, DOI 10.17487/RFC8929,
November 2020, <https://www.rfc-editor.org/info/rfc8929>. November 2020, <https://www.rfc-editor.org/info/rfc8929>.
Appendix A. Example Compression Appendix A. Example Compression
Figure 13 illustrates the case in Storing mode where the packet is Figure 13 illustrates the case in Storing mode where the packet is
received from the Internet, then the Root encapsulates the packet to received from the Internet, then the root encapsulates the packet to
insert the RPI and deliver it to the 6LR that is the parent and last insert the RPI and deliver it to the 6LR that is the parent and last
hop to the final destination, which is not known to support hop to the final destination, which is not known to support
[RFC8138]. [RFC8138].
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
|11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP |11110001|SRH-6LoRH| RPI- |IP-in-IP| NH=1 |11110CPP| UDP | UDP
|Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld |Page 1 |Type1 S=0| 6LoRH | 6LoRH |LOWPAN_IPHC| UDP | hdr |Payld
+-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-... +-+ ... -+-+ ... +-+- ... -+-+ ... -+-+-+ ... +-+-+ ... -+ ... +-...
<-4 bytes-> <- RFC 6282 -> <-4 bytes-> <- RFC 6282 ->
<- No RPL artifact ... <- No RPL artifact ...
skipping to change at line 1916 skipping to change at line 1917
The difference from the example presented in Figure 19 of [RFC8138] The difference from the example presented in Figure 19 of [RFC8138]
is the addition of an SRH-6LoRH before the RPI-6LoRH to transport the is the addition of an SRH-6LoRH before the RPI-6LoRH to transport the
compressed address of the 6LR as the destination address of the outer compressed address of the 6LR as the destination address of the outer
IPv6 header. In Figure 19 of [RFC8138], the destination IP of the IPv6 header. In Figure 19 of [RFC8138], the destination IP of the
outer header was elided and was implicitly the same address as the outer header was elided and was implicitly the same address as the
destination of the inner header. Type 1 was arbitrarily chosen, and destination of the inner header. Type 1 was arbitrarily chosen, and
the size of 0 denotes a single address in the SRH. the size of 0 denotes a single address in the SRH.
In Figure 13, the source of the IPv6-in-IPv6 encapsulation is the In Figure 13, the source of the IPv6-in-IPv6 encapsulation is the
Root, so it is elided in the IPv6-in-IPv6 6LoRH. The destination is root, so it is elided in the IPv6-in-IPv6 6LoRH. The destination is
the parent 6LR of the destination of the encapsulated packet, so it the parent 6LR of the destination of the encapsulated packet, so it
cannot be elided. If the DODAG is operated in Storing mode, it is cannot be elided. If the DODAG is operated in Storing mode, it is
the single entry in the SRH-6LoRH and the SRH-6LoRH Size is encoded the single entry in the SRH-6LoRH and the SRH-6LoRH Size is encoded
as 0. The SRH-6LoRH is the first 6LoRH in the chain. In this as 0. The SRH-6LoRH is the first 6LoRH in the chain. In this
particular example, the 6LR address can be compressed to 2 bytes, so particular example, the 6LR address can be compressed to 2 bytes, so
a Type of 1 is used. The result is that the total length of the SRH- a Type of 1 is used. The result is that the total length of the SRH-
6LoRH is 4 bytes. 6LoRH is 4 bytes.
In Non-Storing mode, the encapsulation from the Root would be similar In Non-Storing mode, the encapsulation from the root would be similar
to that represented in Figure 13 with possibly more hops in the to that represented in Figure 13 with possibly more hops in the
SRH-6LoRH and possibly multiple SRH-6LoRHs if the various addresses SRH-6LoRH and possibly multiple SRH-6LoRHs if the various addresses
in the routing header are not compressed to the same format. Note in the routing header are not compressed to the same format. Note
that on the last hop to the parent 6LR, the RH3 is consumed and that on the last hop to the parent 6LR, the RH3 is consumed and
removed from the compressed form, so the use of Non-Storing mode removed from the compressed form, so the use of Non-Storing mode
vs. Storing mode is indistinguishable from the packet format. vs. Storing mode is indistinguishable from the packet format.
The SRH-6LoRHs are followed by the RPI-6LoRH and then the IPv6-in- The SRH-6LoRHs are followed by the RPI-6LoRH and then the IPv6-in-
IPv6 6LoRH. When the IPv6-in-IPv6 6LoRH is removed, all the 6LoRH IPv6 6LoRH. When the IPv6-in-IPv6 6LoRH is removed, all the 6LoRH
Headers that precede it are also removed. The Paging Dispatch Headers that precede it are also removed. The Paging Dispatch
 End of changes. 74 change blocks. 
126 lines changed or deleted 127 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/