< draft-ietf-6lo-rfc6775-update-18.txt   draft-ietf-6lo-rfc6775-update-19.txt >
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Updates: 6775 (if approved) E. Nordmark Updates: 6775 (if approved) E. Nordmark
Intended status: Standards Track Zededa Intended status: Standards Track Zededa
Expires: October 8, 2018 S. Chakrabarti Expires: October 25, 2018 S. Chakrabarti
Verizon Verizon
C. Perkins C. Perkins
Futurewei Futurewei
April 6, 2018 April 23, 2018
Registration Extensions for 6LoWPAN Neighbor Discovery Registration Extensions for 6LoWPAN Neighbor Discovery
draft-ietf-6lo-rfc6775-update-18 draft-ietf-6lo-rfc6775-update-19
Abstract Abstract
This specification updates RFC 6775 - 6LoWPAN Neighbor Discovery, to This specification updates RFC 6775 - 6LoWPAN Neighbor Discovery, to
clarify the role of the protocol as a registration technique, clarify the role of the protocol as a registration technique,
simplify the registration operation in 6LoWPAN routers, as well as to simplify the registration operation in 6LoWPAN routers, as well as to
provide enhancements to the registration capabilities and mobility provide enhancements to the registration capabilities and mobility
detection for different network topologies including the backbone detection for different network topologies including the backbone
routers performing proxy Neighbor Discovery in a low power network. routers performing proxy Neighbor Discovery in a low power network.
skipping to change at page 1, line 40 skipping to change at page 1, line 40
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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 October 8, 2018. This Internet-Draft will expire on October 25, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Subset of a 6LoWPAN Glossary . . . . . . . . . . . . . . 4 2.2. References . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. References . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4. Subset of a 6LoWPAN Glossary . . . . . . . . . . . . . . 6
3. Applicability of Address Registration Options . . . . . . . . 7 3. Applicability of Address Registration Options . . . . . . . . 7
4. Extended ND Options and Messages . . . . . . . . . . . . . . 8 4. Extended ND Options and Messages . . . . . . . . . . . . . . 8
4.1. Extended Address Registration Option (EARO) . . . . . . . 8 4.1. Extended Address Registration Option (EARO) . . . . . . . 8
4.2. Extended Duplicate Address Message Formats . . . . . . . 11 4.2. Extended Duplicate Address Message Formats . . . . . . . 12
4.3. New 6LoWPAN Capability Bits in the Capability Indication 4.3. New 6LoWPAN Capability Bits in the Capability Indication
Option . . . . . . . . . . . . . . . . . . . . . . . . . 12 Option . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 13 5. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 14
5.1. Extending the Address Registration Option . . . . . . . . 15 5.1. Extending the Address Registration Option . . . . . . . . 15
5.2. Transaction ID . . . . . . . . . . . . . . . . . . . . . 16 5.2. Transaction ID . . . . . . . . . . . . . . . . . . . . . 16
5.2.1. Comparing TID values . . . . . . . . . . . . . . . . 16 5.2.1. Comparing TID values . . . . . . . . . . . . . . . . 16
5.3. Registration Ownership Verifier . . . . . . . . . . . . . 18 5.3. Registration Ownership Verifier . . . . . . . . . . . . . 18
5.4. Extended Duplicate Address Messages . . . . . . . . . . . 19 5.4. Extended Duplicate Address Messages . . . . . . . . . . . 19
5.5. Registering the Target Address . . . . . . . . . . . . . 19 5.5. Registering the Target Address . . . . . . . . . . . . . 19
5.6. Link-Local Addresses and Registration . . . . . . . . . . 20 5.6. Link-Local Addresses and Registration . . . . . . . . . . 20
5.7. Maintaining the Registration States . . . . . . . . . . . 21 5.7. Maintaining the Registration States . . . . . . . . . . . 22
6. Backward Compatibility . . . . . . . . . . . . . . . . . . . 23 6. Backward Compatibility . . . . . . . . . . . . . . . . . . . 23
6.1. Signaling EARO Capability Support . . . . . . . . . . . . 23 6.1. Signaling EARO Capability Support . . . . . . . . . . . . 24
6.2. First Exchanges . . . . . . . . . . . . . . . . . . . . . 24 6.2. RFC6775-only 6LoWPAN Node . . . . . . . . . . . . . . . . 24
6.3. RFC6775-only 6LoWPAN Node . . . . . . . . . . . . . . . . 24 6.3. RFC6775-only 6LoWPAN Router . . . . . . . . . . . . . . . 25
6.4. RFC6775-only 6LoWPAN Router . . . . . . . . . . . . . . . 24 6.4. RFC6775-only 6LoWPAN Border Router . . . . . . . . . . . 25
6.5. RFC6775-only 6LoWPAN Border Router . . . . . . . . . . . 25
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 27 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 27
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
9.1. ARO Flags . . . . . . . . . . . . . . . . . . . . . . . . 28 9.1. ARO Flags . . . . . . . . . . . . . . . . . . . . . . . . 28
9.2. ICMP Codes . . . . . . . . . . . . . . . . . . . . . . . 28 9.2. ICMP Codes . . . . . . . . . . . . . . . . . . . . . . . 28
9.3. New ARO Status values . . . . . . . . . . . . . . . . . . 29 9.3. New ARO Status values . . . . . . . . . . . . . . . . . . 29
9.4. New 6LoWPAN capability Bits . . . . . . . . . . . . . . . 30 9.4. New 6LoWPAN capability Bits . . . . . . . . . . . . . . . 30
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 31 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 31
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
11.1. Normative References . . . . . . . . . . . . . . . . . . 31 11.1. Normative References . . . . . . . . . . . . . . . . . . 31
11.2. Terminology Related References . . . . . . . . . . . . . 32 11.2. Terminology Related References . . . . . . . . . . . . . 32
11.3. Informative References . . . . . . . . . . . . . . . . . 32 11.3. Informative References . . . . . . . . . . . . . . . . . 32
11.4. External Informative References . . . . . . . . . . . . 36 11.4. External Informative References . . . . . . . . . . . . 36
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2. Terminology 2. Terminology
2.1. BCP 14 2.1. BCP 14
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all 14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2.2. Subset of a 6LoWPAN Glossary 2.2. References
This document often uses the following acronyms:
6BBR: 6LoWPAN Backbone Router (proxy for the registration)
6LBR: 6LoWPAN Border Router (authoritative on DAD)
6LN: 6LoWPAN Node
6LR: 6LoWPAN Router (relay to the registration process)
6CIO: Capability Indication Option
(E)ARO: (Extended) Address Registration Option
(E)DAR: (Extended) Duplicate Address Request
(E)DAC: (Extended) Duplicate Address Confirmation
DAD: Duplicate Address Detection
DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network (a typical IoT network)
NA: Neighbor Advertisement
NCE: Neighbor Cache Entry
ND: Neighbor Discovery
NDP: Neighbor Discovery Protocol
NS: Neighbor Solicitation
ROVR: Registration Ownership Verifier (pronounced rover)
RPL: IPv6 Routing Protocol for LLNs (pronounced ripple)
RA: Router Advertisement
RS: Router Solicitation
TSCH: Timeslotted Channel Hopping
TID: Transaction ID (a sequence counter in the EARO)
2.3. References
The Terminology used in this document is consistent with and The Terminology used in this document is consistent with and
incorporates that described in Terms Used in Routing for Low-Power incorporates that described in Terms Used in Routing for Low-Power
and Lossy Networks (LLNs). [RFC7102]. and Lossy Networks (LLNs). [RFC7102].
Other terms in use in LLNs are found in Terminology for Constrained- Other terms in use in LLNs are found in Terminology for Constrained-
Node Networks [RFC7228]. Node Networks [RFC7228].
Readers are expected to be familiar with all the terms and concepts Readers are expected to be familiar with all the terms and concepts
that are discussed in that are discussed in
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o "Problem Statement and Requirements for IPv6 over Low-Power o "Problem Statement and Requirements for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606], Wireless Personal Area Network (6LoWPAN) Routing" [RFC6606],
o "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): o "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals" [RFC4919] and Overview, Assumptions, Problem Statement, and Goals" [RFC4919] and
o "Neighbor Discovery Optimization for Low-power and Lossy Networks" o "Neighbor Discovery Optimization for Low-power and Lossy Networks"
[RFC6775]. [RFC6775].
2.4. New Terms 2.3. New Terms
This specification introduces the following terminology:
Backbone Link: An IPv6 transit link that interconnects two or more Backbone Link: An IPv6 transit link that interconnects two or more
Backbone Routers. It is expected to be of high speed compared Backbone Routers. It is expected to be of high speed compared
to the LLN in order to carry the traffic that is required to to the LLN in order to carry the traffic that is required to
federate multiple segments of the potentially large LLN into a federate multiple segments of the potentially large LLN into a
single IPv6 subnet. single IPv6 subnet.
Backbone Router: A logical network function in an IPv6 router that Backbone Router: A logical network function in an IPv6 router that
federates an LLN over a Backbone Link. In order to do so, the federates an LLN over a Backbone Link. In order to do so, the
Backbone Router (6BBR) proxies the 6LoWPAN ND operations Backbone Router (6BBR) proxies the 6LoWPAN ND operations
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over the backbone, typically IPv6 ND. Note that 6BBR is a over the backbone, typically IPv6 ND. Note that 6BBR is a
logical function, just like 6LR and 6LBR, and that the same logical function, just like 6LR and 6LBR, and that the same
physical router may operate all three. physical router may operate all three.
Extended LLN: Multiple LLNs as defined in [RFC6550], interconnected Extended LLN: Multiple LLNs as defined in [RFC6550], interconnected
by a Backbone Link via Backbone Routers, and forming a single by a Backbone Link via Backbone Routers, and forming a single
IPv6 Multi-Link Subnet. IPv6 Multi-Link Subnet.
Registration: The process during which a 6LN registers an IPv6 Registration: The process during which a 6LN registers an IPv6
Address with a 6LR in order to obtain services such as DAD and Address with a 6LR in order to obtain services such as DAD and
routing back. In a Route-Over network, a router that provides routing back. In a Route-Over network, a 6LBR may serve as
connectivity to the LLN (typically a 6LBR, e.g., collocated proxy for the registration of the 6LN to the 6BBR so the 6BBR
with a RPL Root) may serve as proxy for the registration of the can provide IPv6 ND proxy services over the Backbone.
6LN to the 6BBR so the 6BBR can provide IPv6 ND proxy services
over the Backbone.
Binding: The association between an IP address, a MAC address, a Binding: The association between an IP address, a MAC address, a
physical port on a switch, and other information about the node physical port on a switch, and other information about the node
that owns the IP Address. that owns the IP Address.
Registered Node: The 6LN for which the registration is performed, Registered Node: The 6LN for which the registration is performed,
and which owns the fields in the Extended ARO option. and which owns the fields in the Extended ARO option.
Registering Node: The node that performs the registration; this may Registering Node: The node that performs the registration; this may
be the Registered Node, or a proxy such as a 6LBR performing a be the Registered Node, or a proxy such as a 6LBR performing a
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or is being registered. or is being registered.
RFC6775-only: Applied to an implementation, a type of node, or a RFC6775-only: Applied to an implementation, a type of node, or a
type of message, this adjective indicates a behavior that is type of message, this adjective indicates a behavior that is
strictly as specified by [RFC6775] as opposed to updated with strictly as specified by [RFC6775] as opposed to updated with
this specification. this specification.
updated: Qualifies a 6LN, a 6LR, or a 6LBR that supports this updated: Qualifies a 6LN, a 6LR, or a 6LBR that supports this
specification. specification.
2.4. Subset of a 6LoWPAN Glossary
This document often uses the following acronyms:
6BBR: 6LoWPAN Backbone Router (proxy for the registration)
6LBR: 6LoWPAN Border Router (authoritative on DAD)
6LN: 6LoWPAN Node
6LR: 6LoWPAN Router (relay to the registration process)
6CIO: Capability Indication Option
(E)ARO: (Extended) Address Registration Option
(E)DAR: (Extended) Duplicate Address Request
(E)DAC: (Extended) Duplicate Address Confirmation
DAD: Duplicate Address Detection
DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network (a typical IoT network)
NA: Neighbor Advertisement
NCE: Neighbor Cache Entry
ND: Neighbor Discovery
NDP: Neighbor Discovery Protocol
NS: Neighbor Solicitation
ROVR: Registration Ownership Verifier (pronounced rover)
RPL: IPv6 Routing Protocol for LLNs (pronounced ripple)
RA: Router Advertisement
RS: Router Solicitation
TSCH: Timeslotted Channel Hopping
TID: Transaction ID (a sequence counter in the EARO)
3. Applicability of Address Registration Options 3. Applicability of Address Registration Options
The purpose of the Address Registration Option (ARO) in [RFC6775] is The purpose of the Address Registration Option (ARO) in [RFC6775] is
to facilitate duplicate address detection (DAD) for hosts as well as to facilitate duplicate address detection (DAD) for hosts as well as
to populate Neighbor Cache Entries (NCEs) [RFC4861] in the routers. to populate Neighbor Cache Entries (NCEs) [RFC4861] in the routers.
This reduces the reliance on multicast operations, which are often as This reduces the reliance on multicast operations, which are often as
intrusive as broadcast, in IPv6 ND operations. intrusive as broadcast, in IPv6 ND operations.
With this specification, a failed or useless registration can be With this specification, a failed or useless registration can be
detected by a 6LR or a 6LBR for reasons other than address detected by a 6LR or a 6LBR for reasons other than address
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4. Extended ND Options and Messages 4. Extended ND Options and Messages
This specification does not introduce new options, but it modifies This specification does not introduce new options, but it modifies
existing ones and updates the associated behaviors as specified in existing ones and updates the associated behaviors as specified in
the following subsections. the following subsections.
4.1. Extended Address Registration Option (EARO) 4.1. Extended Address Registration Option (EARO)
The Address Registration Option (ARO) is defined in section 4.1 of The Address Registration Option (ARO) is defined in section 4.1 of
[RFC6775]. This specification introduces the Extended Address [RFC6775].
Registration Option (EARO) based on the ARO for use in NS and NA
messages. The EARO conveys additional information such as a sequence This specification introduces the Extended Address Registration
counter called Transaction ID (TID) that is used to determine the Option (EARO) based on the ARO for use in NS and NA messages. The
latest location of a registering mobile device. A 'T' flag is added EARO conveys additional information such as a sequence counter called
to indicate that the TID field is populated. Transaction ID (TID) that is used to determine the latest location of
a registering mobile device. A new 'T' flag indicates that the TID
field is populated and that the option is an EARO.
The EARO also signals whether the 6LN expects routing or proxy The EARO also signals whether the 6LN expects routing or proxy
services from the 6LR using a new 'R' flag. services from the 6LR using a new 'R' flag.
The EUI-64 field is overloaded and renamed ROVR in order to carry The EUI-64 field is overloaded and renamed ROVR in order to carry
different types of information, e.g., cryptographic information of different types of information, e.g., cryptographic information of
variable size. A larger ROVR size may be used if and only if variable size. A larger ROVR size may be used if and only if
backward compatibility is not an issue in the particular deployment. backward compatibility is not an issue in the particular deployment.
Note that the length of the ROVR field expressed in units of 8 bytes
is the Length of the option minus 1.
Section 5.1 discusses those changes in depth. Section 5.1 discusses those changes in depth.
An NS message with an EARO is a registration if and only if it also
carries an SLLA Option [RFC6775]. The EARO is also used in NS and NA
messages between Backbone Routers [I-D.ietf-6lo-backbone-router] over
the Backbone Link to sort out the distributed registration state; in
that case, it does not carry the SLLA Option and is not confused with
a registration.
When using the EARO, the address being registered is found in the
Target Address field of the NS and NA messages.
The EARO extends the ARO and is indicated by the 'T' flag being set.
The format of the EARO is as follows: The format of the EARO is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Status | Reserved | | Type | Length | Status | Opaque |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R|T| TID | Registration Lifetime | | Rsvd | I |R|T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
... Registration Ownership Verifier ... ... Registration Ownership Verifier ...
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: EARO Figure 1: EARO
Option Fields Option Fields:
Type: 33 Type: 33
Length: 8-bit unsigned integer. The length of the whole Length: 8-bit unsigned integer. The length of the whole
option in units of 8 bytes. It MUST be 2 when option in units of 8 bytes. It MUST be 2 when
operating in a backward-compatible mode with a ROVR operating in a backward-compatible mode with a ROVR
size of 64 bits. It MAY be 3, 4 or 5, denoting a size of 64 bits. It MAY be 3, 4 or 5, denoting a
ROVR size of 128, 192 and 256 bits respectively. ROVR size of 128, 192 and 256 bits respectively.
Status: 8-bit unsigned integer. Indicates the status of a Status: 8-bit unsigned integer. Indicates the status of a
registration in the NA response. MUST be set to 0 in registration in the NA response. MUST be set to 0 in
NS messages. See Table 1 below. NS messages. See Table 1 below.
Rsvd (Reserved): This field is unused. It MUST be initialized to
zero by the sender and MUST be ignored by the
receiver.
Opaque: One-byte Opaque field; this is an octet is opaque to
ND but that the 6LN may wish to pass transparently to
another process. This field MUST be set to zero
unless the 6LN has a policy to set it otherwise.
I: Two-bit Integer: A value of zero indicates that the
Opaque field carries an abstract index that is used
to decide in which routing topology the address is
expected to be injected. In that case, the Opaque
field is passed to a routing process with the
indication that this is a topology information, and
the value of 0 indicates default. All other values
of "I" are reserved and MUST NOT be used.
R: One-bit flag. If the 'R' flag is set, the
Registering Node expects that the 6LR ensures
reachability for the registered address, e.g., by
injecting the address in a Route-Over routing
protocol or proxying ND over a Backbone Link.
T: One-bit flag. Set if the next octet is used as a
TID.
TID: One-byte integer; a Transaction ID that is maintained
by the node and incremented with each transaction of
one or more registrations performed at the same time
to one or more respective 6LRs. This field MUST be
ignored if the 'T' flag is not set.
Registration Lifetime: 16-bit integer; expressed in minutes. A
value of 0 indicates that the registration has ended
and that the associated state MUST be removed.
Registration Ownership Verifier (ROVR): Enables the correlation
between multiple attempts to register a same IPv6
Address. The ROVR is stored in the 6LR and the 6LBR
in the state associated to the registration. This
can be a unique ID of the Registering Node, such as
the EUI-64 address of an interface. This can also be
a token obtained with cryptographic methods which can
be used in additional protocol exchanges to associate
a cryptographic identity (key) with this registration
to ensure that only the owner can modify it later.
The scope of a ROVR is the registration of a
particular IPv6 Address and it must not be used to
correlate registrations of different addresses.
+-------+-----------------------------------------------------------+ +-------+-----------------------------------------------------------+
| Value | Description | | Value | Description |
+-------+-----------------------------------------------------------+ +-------+-----------------------------------------------------------+
| 0..2 | See [RFC6775]. Note: a Status of 1 ("Duplicate Address") | | 0..2 | See [RFC6775]. Note: a Status of 1 ("Duplicate Address") |
| | applies to the Registered Address. If the Source Address | | | applies to the Registered Address. If the Source Address |
| | conflicts with an existing registration, "Duplicate | | | conflicts with an existing registration, "Duplicate |
| | Source Address" MUST be used. | | | Source Address" MUST be used. |
| | | | | |
| 3 | Moved: The registration failed because it is not the | | 3 | Moved: The registration failed because it is not the |
| | freshest. This Status indicates that the registration is | | | freshest. This Status indicates that the registration is |
skipping to change at page 10, line 7 skipping to change at page 11, line 28
| | progressed slowly in the network and was passed by a more | | | progressed slowly in the network and was passed by a more |
| | recent one. It could also indicate a ROVR collision. | | | recent one. It could also indicate a ROVR collision. |
| | | | | |
| 4 | Removed: The binding state was removed. This status may | | 4 | Removed: The binding state was removed. This status may |
| | be placed in an NA(EARO) message that is sent as the | | | be placed in an NA(EARO) message that is sent as the |
| | rejection of a proxy registration to a Backbone Router, | | | rejection of a proxy registration to a Backbone Router, |
| | or in an asynchronous NA(EARO) at any time. | | | or in an asynchronous NA(EARO) at any time. |
| | | | | |
| 5 | Validation Requested: The Registering Node is challenged | | 5 | Validation Requested: The Registering Node is challenged |
| | for owning the Registered Address or for being an | | | for owning the Registered Address or for being an |
| | acceptable proxy for the registration. This Status is | | | acceptable proxy for the registration. This Status may |
| | expected in asynchronous messages from a registrar (6LR, | | | be received in asynchronous DAC or NA messages from a |
| | 6LBR, 6BBR) to indicate that the registration state is | | | registrar (6LR, 6LBR, 6BBR). |
| | removed, for instance, due to a movement of the device. |
| | | | | |
| 6 | Duplicate Source Address: The address used as source of | | 6 | Duplicate Source Address: The address used as source of |
| | the NS(ARO) conflicts with an existing registration. | | | the NS(EARO) conflicts with an existing registration. |
| | | | | |
| 7 | Invalid Source Address: The address used as source of the | | 7 | Invalid Source Address: The address used as source of the |
| | NS(ARO) is not a Link-Local Address as prescribed by this | | | NS(EARO) is not a Link-Local Address. |
| | document. |
| | | | | |
| 8 | Registered Address topologically incorrect: The address | | 8 | Registered Address topologically incorrect: The address |
| | being registered is not usable on this link, e.g., it is | | | being registered is not usable on this link, e.g., it is |
| | not topologically correct | | | not topologically correct |
| | | | | |
| 9 | 6LBR Registry saturated: A new registration cannot be | | 9 | 6LBR Registry saturated: A new registration cannot be |
| | accepted because the 6LBR Registry is saturated. Note: | | | accepted because the 6LBR Registry is saturated. Note: |
| | this code is used by 6LBRs instead of Status 2 when | | | this code is used by 6LBRs instead of Status 2 when |
| | responding to a Duplicate Address message exchange and is | | | responding to a Duplicate Address message exchange and is |
| | passed on to the Registering Node by the 6LR. | | | passed on to the Registering Node by the 6LR. |
| | | | | |
| 10 | Validation Failed: The proof of ownership of the | | 10 | Validation Failed: The proof of ownership of the |
| | registered address is not correct. | | | registered address is not correct. |
+-------+-----------------------------------------------------------+ +-------+-----------------------------------------------------------+
Table 1: EARO Status Table 1: EARO Status
Reserved: This field is unused. It MUST be initialized to zero
by the sender and MUST be ignored by the receiver.
R: One-bit flag. If the 'R' flag is set, the
Registering Node expects that the 6LR ensures
reachability for the registered address, e.g., by
injecting the address in a Route-Over routing
protocol or proxying ND over a Backbone Link.
T: One-bit flag. Set if the next octet is used as a
TID.
TID: One-byte integer; a Transaction ID that is maintained
by the node and incremented with each transaction of
one or more registrations performed at the same time
to one or more respective 6LRs. This field MUST be
ignored if the 'T' flag is not set.
Registration Lifetime: 16-bit integer; expressed in minutes. 0
means that the registration has ended and the
associated state MUST be removed.
Registration Ownership Verifier (ROVR): Enables the correlation
between multiple attempts to register a same IPv6
Address. The ROVR is stored in the 6LR and the 6LBR
in the state associated to the registration. This
can be a unique ID of the Registering Node, such as
the EUI-64 address of an interface. This can also be
a token obtained with cryptographic methods which can
be used in additional protocol exchanges to associate
a cryptographic identity (key) with this registration
to ensure that only the owner can modify it later.
The scope of a ROVR is the registration of a
particular IPv6 Address and it must not be used to
correlate registrations of different addresses.
4.2. Extended Duplicate Address Message Formats 4.2. Extended Duplicate Address Message Formats
The DAR and DAC messages are defined in section 4.4 of [RFC6775]. The DAR and DAC messages are defined in section 4.4 of [RFC6775].
Those messages follow a common base format, which enables information Those messages follow a common base format, which enables information
from the ARO to be transported over multiple hops. from the ARO to be transported over multiple hops.
Those messages are extended to adapt to the new EARO format, as Those messages are extended to adapt to the new EARO format, as
follows: follows:
0 1 2 3 0 1 2 3
skipping to change at page 12, line 27 skipping to change at page 12, line 36
+ + + +
| | | |
+ Registered Address + + Registered Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Duplicate Address Messages Format Figure 2: Duplicate Address Messages Format
Modified Message Fields Modified Message Fields:
Code: The ICMP Code as defined in [RFC4443]. The ICMP Code Code: The ICMP Code as defined in [RFC4443]. The ICMP Code
MUST be set to 1 with this specification. An non- MUST be set to 1 with this specification. An non-
null value of the ICMP Code indicates support for null value of the ICMP Code indicates support for
this specification. this specification.
TID: 1-byte integer; same definition and processing as the TID: 1-byte integer; same definition and processing as the
TID in the EARO as defined in Section 4.1. This TID in the EARO as defined in Section 4.1. This
field MUST be ignored if the ICMP Code is null. field MUST be ignored if the ICMP Code is null.
Registration Ownership Verifier (ROVR): The size of the ROVR is Registration Ownership Verifier (ROVR): The size of the ROVR is
computed from the overall size of the IPv6 packet. computed from the overall size of the IPv6 packet.
It MUST be 64bits long when operating in backward- This field has the same definition and processing as
compatible mode. This field has the same definition the ROVR in the EARO option as defined in
and processing as the ROVR in the EARO option as Section 4.1.
defined in Section 4.1.
4.3. New 6LoWPAN Capability Bits in the Capability Indication Option 4.3. New 6LoWPAN Capability Bits in the Capability Indication Option
This specification defines 5 new capability bits for use in the 6CIO, This specification defines 5 new capability bits for use in the 6CIO,
which was introduced by [RFC7400] for use in IPv6 ND RA messages. which was introduced by [RFC7400] for use in IPv6 ND RA messages.
This specification introduces the "E" flag to indicate that extended The new "E" flag indicates that EARO can be used in a registration.
ARO can be used in a registration. A 6LR that supports this A 6LR that supports this specification MUST set the "E" flag.
specification MUST set the "E" flag.
A similar flag "D" indicates the support of Extended Duplicate A similar "D" flag indicates the support of EDA Messages by the 6LBR;
Address Messages by the 6LBR; A 6LBR that supports this specification A 6LBR that supports this specification MUST set the "D" flag. The
MUST set the "D" flag. The "D" flag is learned from advertisements "D" flag is learned from advertisements by a 6LBR, and is propagated
by a 6LBR, and is propagated down a graph of 6LRs as a node acting as down a graph of 6LRs as a node acting as 6LN registers to a 6LR
6LN registers to a 6LR (which could be the 6LBR), and in turn becomes (which could be the 6LBR), and in turn becomes a 6LR to which other
a 6LR to which other 6LNs will register. 6LNs will register.
The new "L", "B", and "P" flags, indicate whether a router is capable The new "L", "B", and "P" flags, indicate whether a router is capable
of acting as 6LR, 6LBR, and 6BBR, respectively. These flags are not of acting as 6LR, 6LBR, and 6BBR, respectively. These flags are not
mutually exclusive and a node MUST set all the flags that are mutually exclusive and a node MUST set all the flags that are
relevant to it. relevant to it.
As an example, a 6LBR sets the "B" and "D" flags. If it acts as a
6LR, then it sets the "L" and "E" flags. If it is collocated with a
6BBR, then it also sets the "P" flag.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 1 | Reserved |D|L|B|P|E|G| | Type | Length = 1 | Reserved |D|L|B|P|E|G|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: New capability Bits L, B, P, E in the 6CIO Figure 3: New capability Bits L, B, P, E in the 6CIO
Option Fields Option Fields:
Type: 36 Type: 36
L: Node is a 6LR. L: Node is a 6LR.
B: Node is a 6LBR. B: Node is a 6LBR.
P: Node is a 6BBR. P: Node is a 6BBR.
E: Node supports registrations based on EARO. E: Node supports registrations based on EARO.
D: 6LBR supports EDA messages. D: 6LBR supports EDA messages.
As an example, a 6LBR sets the "B" and "D" flags. If it acts as a
6LR, then it sets the "L" and "E" flags. If it is collocated with a
6BBR, then it also sets the "P" flag.
5. Updating RFC 6775 5. Updating RFC 6775
The Extended Address Registration Option (EARO) (see Section 4.1) The Extended Address Registration Option (EARO) (see Section 4.1)
replaces the ARO used within Neighbor Discovery NS and NA messages replaces the ARO used within Neighbor Discovery NS and NA messages
between a 6LN and its 6LR. Similarly, the EDA messages, EDAR and between a 6LN and its 6LR. Similarly, the EDA messages, EDAR and
EDAC, replace the DAR and DAC messages so as to transport the new EDAC, replace the DAR and DAC messages so as to transport the new
information between 6LRs and 6LBRs across an LLN mesh such as a information between 6LRs and 6LBRs across an LLN mesh such as a
6TiSCH network. 6TiSCH network.
The extensions to the ARO option are used in the Duplicate Address The extensions to the ARO option are used in the Duplicate Address
skipping to change at page 15, line 33 skipping to change at page 15, line 39
o The EUI-64 field in the ARO Option is renamed Registration o The EUI-64 field in the ARO Option is renamed Registration
Ownership Verifier (ROVR) and is not required to be derived from a Ownership Verifier (ROVR) and is not required to be derived from a
MAC address (see Section 5.3). MAC address (see Section 5.3).
o The option Length MAY be different than 2 and take a value between o The option Length MAY be different than 2 and take a value between
3 and 5, in which case the EARO is not backward compatible with an 3 and 5, in which case the EARO is not backward compatible with an
ARO. The increase of size corresponds to a larger ROVR field, so ARO. The increase of size corresponds to a larger ROVR field, so
the size of the ROVR is inferred from the option Length. the size of the ROVR is inferred from the option Length.
o A new Opaque field is introduced to carry opaque information in
case the registration is relayed to another process, e.g.;
injected in a routing protocol. A new "I" field provides an
abstract type for the opaque information, and from which the 6LN
derives to which other process the opaque is expected to be
passed. A value of Zero for I indicates an abstract topological
information to be passed to a routing process if the registration
is redistributed. In that case, a value of Zero for the Opaque
field is backward-compatible with the reserved fields that are
overloaded, and the meaning is to use the default topology.
o This document specifies a new flag in the EARO, the 'R' flag. If o This document specifies a new flag in the EARO, the 'R' flag. If
the 'R' flag is set, the Registering Node expects that the 6LR the 'R' flag is set, the Registering Node expects that the 6LR
ensures reachability for the Registered Address, e.g., by means of ensures reachability for the Registered Address, e.g., by means of
routing or proxying ND. Conversely, when it is not set, the 'R' routing or proxying ND. Conversely, when it is not set, the 'R'
flag indicates that the Registering Node is a router, which for flag indicates that the Registering Node is a router, which for
instance participates to a Route-Over routing protocol such as RPL instance participates to a Route-Over routing protocol such as RPL
[RFC6550] and that it will take care of injecting its Address over [RFC6550] and that it will take care of injecting its Address over
the routing protocol by itself. A 6LN that acts only as a host, the routing protocol by itself. A 6LN that acts only as a host,
when registering, MUST set the 'R' flag to indicate that it is not when registering, MUST set the 'R' flag to indicate that it is not
a router and that it will not handle its own reachability. A 6LR a router and that it will not handle its own reachability. A 6LR
skipping to change at page 19, line 26 skipping to change at page 19, line 41
presented in Section 4.2. presented in Section 4.2.
As with the EARO, the Extended Duplicate Address messages are As with the EARO, the Extended Duplicate Address messages are
backward compatible with the RFC6775-only versions as long as the backward compatible with the RFC6775-only versions as long as the
ROVR field is 64 bits long. Remarks concerning backwards ROVR field is 64 bits long. Remarks concerning backwards
compatibility for the protocol between the 6LN and the 6LR apply compatibility for the protocol between the 6LN and the 6LR apply
similarly between a 6LR and a 6LBR. similarly between a 6LR and a 6LBR.
5.5. Registering the Target Address 5.5. Registering the Target Address
An NS message with an EARO is a registration if and only if it also
carries an SLLA Option [RFC6775]. The EARO is also used in NS and NA
messages between Backbone Routers [I-D.ietf-6lo-backbone-router] over
the Backbone Link to sort out the distributed registration state; in
that case, it does not carry the SLLA Option and is not confused with
a registration.
The Registering Node is the node that performs the registration to The Registering Node is the node that performs the registration to
the 6BBR. As in [RFC6775], it may be the Registered Node as well, in the 6BBR. As in [RFC6775], it may be the Registered Node as well, in
which case it registers one of its own addresses and indicates its which case it registers one of its own addresses and indicates its
own MAC Address as Source Link Layer Address (SLLA) in the NS(EARO). own MAC Address as Source Link Layer Address (SLLA) in the NS(EARO).
This specification adds the capability to proxy the registration This specification adds the capability to proxy the registration
operation on behalf of a Registered Node that is reachable over an operation on behalf of a Registered Node that is reachable over an
LLN mesh. In that case, if the Registered Node is reachable from the LLN mesh. In that case, if the Registered Node is reachable from the
6BBR over a Mesh-Under mesh, the Registering Node indicates the MAC 6BBR over a Mesh-Under mesh, the Registering Node indicates the MAC
Address of the Registered Node as the SLLA in the NS(EARO). If the Address of the Registered Node as the SLLA in the NS(EARO). If the
Registered Node is reachable over a Route-Over mesh from the Registered Node is reachable over a Route-Over mesh from the
Registering Node, the SLLA in the NS(ARO) is that of the Registering Registering Node, the SLLA in the NS(ARO) is that of the Registering
Node. This enables the Registering Node to attract the packets from Node. This enables the Registering Node to attract the packets from
the 6BBR and route them over the LLN to the Registered Node. the 6BBR and route them over the LLN to the Registered Node.
In order to enable the latter operation, this specification changes In order to enable the latter operation, this specification changes
the behavior of the 6LN and the 6LR so that the Registered Address is the behavior of the 6LN and the 6LR so that the Registered Address is
found in the Target Address field of the NS and NA messages as found in the Target Address field of the NS and NA messages as
opposed to the Source Address. With this convention, a TLLA option opposed to the Source Address field. With this convention, a TLLA
indicates the link-layer address of the 6LN that owns the address. option indicates the link-layer address of the 6LN that owns the
address.
If Registering Node expects packets for the 6LN, e.g., a 6LBR also If Registering Node expects packets for the 6LN, e.g., a 6LBR also
acting as RPL Root, then it MUST place its own Link Layer Address in acting as RPL Root, then it MUST place its own Link Layer Address in
the SLLA Option that MUST always be placed in a registration NS(EARO) the SLLA Option that MUST always be placed in a registration NS(EARO)
message. This maintains compatibility with RFC6775-only 6LoWPAN ND message. This maintains compatibility with RFC6775-only 6LoWPAN ND
[RFC6775]. [RFC6775].
5.6. Link-Local Addresses and Registration 5.6. Link-Local Addresses and Registration
Considering that LLN nodes are often not wired and may move, there is Considering that LLN nodes are often not wired and may move, there is
skipping to change at page 20, line 30 skipping to change at page 21, line 4
An exchange between two nodes using Link-Local Addresses implies that An exchange between two nodes using Link-Local Addresses implies that
they are reachable over one hop. A node MUST register a Link-Local they are reachable over one hop. A node MUST register a Link-Local
Address to a 6LR in order to obtain reachability from that 6LR beyond Address to a 6LR in order to obtain reachability from that 6LR beyond
the current exchange, and in particular to use the Link-Local Address the current exchange, and in particular to use the Link-Local Address
as source address to register other addresses, e.g., global as source address to register other addresses, e.g., global
addresses. addresses.
If there is no collision with an address previously registered to If there is no collision with an address previously registered to
this 6LR by another 6LN, then the Link-Local Address is unique from this 6LR by another 6LN, then the Link-Local Address is unique from
the standpoint of this 6LR and the registration is not a duplicate. the standpoint of this 6LR and the registration is not a duplicate.
Alternatively, two different 6LRs might expose the same Link-Local Alternatively, two different 6LRs might expose the same Link-Local
Address but different link-layer addresses. In that case, a 6LN MUST Address but different link-layer addresses. In that case, a 6LN MUST
only interact with at most one of the 6LRs. only interact with at most one of the 6LRs.
The DAD process between the 6LR and a 6LBR, which is based on an The exchange of EDA messages between the 6LR and a 6LBR, which
exchange of EDA messages, does not need to take place for Link-Local ensures that an address is unique across the domain covered by the
Addresses. 6LBR, does not need to take place for Link-Local Addresses.
When registering to a 6LR that conforms to this specification (see When registering to a 6LR that conforms to this specification, a 6LN
Section 6.2, a node MUST use a Link-Local Address as the source MUST use a Link-Local Address as the source address of the
address of the registration, whatever the type of IPv6 address that registration, whatever the type of IPv6 address that is being
is being registered. That Link-Local Address MUST be either an registered. That Link-Local Address MUST be either an address that
address that is already registered to the 6LR, or the address that is is already registered to the 6LR, or the address that is being
being registered. registered.
A typical flow when a 6LN starts up is that it sends a multicast RS
and receives one or more unicast RA messages. If the 6LR can process
Extended ARO, then it places a 6CIO in its RA message back with the
"E" Flag set as required in Section 6.1.
When a Registering Node does not have an already-registered Address, When a Registering Node does not have an already-registered Address,
it MUST register a Link-Local Address, using it as both the Source it MUST register a Link-Local Address, using it as both the Source
and the Target Address of an NS(EARO) message. In that case, it is and the Target Address of an NS(EARO) message. In that case, it is
RECOMMENDED to use a Link-Local Address that is (expected to be) RECOMMENDED to use a Link-Local Address that is (expected to be)
globally unique, e.g., derived from a globally unique EUI-64 address. globally unique, e.g., derived from a globally unique EUI-64 address.
A 6LR that supports this specification replies with an NA(EARO), For such an address, DAD is not required (see [RFC6775]) and using
setting the appropriate status. the SLLA Option in the NS is actually more consistent with existing
ND specifications such as the "Optimistic Duplicate Address Detection
(ODAD) for IPv6" [RFC4429]. The 6LN MAY then use that address to
register one or more other addresses.
Since there is no exchange of EDA messages for Link-Local Addresses, A 6LR that supports this specification replies with an NA(EARO),
the 6LR may answer immediately to the registration of a Link-Local setting the appropriate status. Since there is no exchange of EDA
Address, based solely on its existing state and the Source Link-Layer messages for Link-Local Addresses, the 6LR may answer immediately to
Option that is placed in the NS(EARO) message as required in the registration of a Link-Local Address, based solely on its
[RFC6775]. existing state and the Source Link-Layer Option that is placed in the
NS(EARO) message as required in [RFC6775].
A node needs to register its IPv6 Global Unicast Addresses (GUAs) to A node needs to register its IPv6 Global Unicast Addresses (GUAs) to
a 6LR in order to establish global reachability for these addresses a 6LR in order to establish global reachability for these addresses
via that 6LR. When registering with an updated 6LR, a Registering via that 6LR. When registering with an updated 6LR, a Registering
Node does not use a GUA as Source Address, in contrast to a node that Node does not use a GUA as Source Address, in contrast to a node that
complies to [RFC6775]. For non-Link-Local Addresses, the exchange of complies to [RFC6775]. For non-Link-Local Addresses, the exchange of
EDA messages MUST conform to [RFC6775], but the extended formats EDA messages MUST conform to [RFC6775], but the extended formats
described in this specification for the DAR and the DAC are used to described in this specification for the DAR and the DAC are used to
relay the extended information in the case of an EARO. relay the extended information in the case of an EARO.
skipping to change at page 23, line 39 skipping to change at page 24, line 27
introduces the 6LoWPAN Capability Indication Option (6CIO) to introduces the 6LoWPAN Capability Indication Option (6CIO) to
indicate a node's capabilities to its peers. The 6CIO MUST be indicate a node's capabilities to its peers. The 6CIO MUST be
present in both Router Solicitation (RS) and Router Advertisement present in both Router Solicitation (RS) and Router Advertisement
(RA) messages, unless the information therein was already shared. (RA) messages, unless the information therein was already shared.
This can have happened in recent exchanges. The information can also This can have happened in recent exchanges. The information can also
be implicit, or pre-configured in all nodes in a network. In any be implicit, or pre-configured in all nodes in a network. In any
case, a 6CIO MUST be placed in an RA message that is sent in response case, a 6CIO MUST be placed in an RA message that is sent in response
to an RS with a 6CIO. to an RS with a 6CIO.
Section 4.3 defines a new flag for the 6CIO to signal support for Section 4.3 defines a new flag for the 6CIO to signal support for
EARO by the issuer of the message and Section 6.2 specifies how the EARO by the issuer of the message. New flags are also added to the
flag is to be used. New flags are also added to the 6CIO to signal 6CIO to signal the sender's capability to act as a 6LR, 6LBR, and
the sender's capability to act as a 6LR, 6LBR, and 6BBR (see 6BBR (see Section 4.3).
Section 4.3).
Section 4.3 also defines a new flag that indicates the support of EDA Section 4.3 also defines a new flag that indicates the support of EDA
messages by the 6LBR. This flag is valid in RA messages but not in messages by the 6LBR. This flag is valid in RA messages but not in
RS messages. More information on the 6LBR is found in a separate RS messages. More information on the 6LBR is found in a separate
Authoritative Border Router Option (ABRO). The ABRO is placed in RA Authoritative Border Router Option (ABRO). The ABRO is placed in RA
messages as prescribed by [RFC6775]; in particular, it MUST be placed messages as prescribed by [RFC6775]; in particular, it MUST be placed
in an RA message that is sent in response to an RS with a 6CIO in an RA message that is sent in response to an RS with a 6CIO
indicating the capability to act as a 6LR, since the RA propagates indicating the capability to act as a 6LR, since the RA propagates
information between routers. information between routers.
6.2. First Exchanges 6.2. RFC6775-only 6LoWPAN Node
A typical flow when a node starts up is that it sends a multicast RS
and receives one or more unicast RA messages. If the 6LR can process
Extended ARO, then it places a 6CIO in its RA message back with the
"E" Flag set as required in Section 6.1.
In order to ensure that it registers a first address successfully a
6LN MAY register a Link Local Address that is derived from an EUI-64,
placing the same address in the Source and Target Address fields of
the NS(EARO) message. For such an address, DAD is not required (see
[RFC6775]) and using the SLLA Option in the NS is actually more
consistent with existing ND specifications such as the "Optimistic
Duplicate Address Detection (ODAD) for IPv6" [RFC4429]. The 6LN MAY
then use that address to register one or more other addresses.
6.3. RFC6775-only 6LoWPAN Node
An RFC6775-only 6LN will use the Registered Address as the source An RFC6775-only 6LN will use the Registered Address as the source
address of the NS message and will not use an EARO. An updated 6LR address of the NS message and will not use an EARO. An updated 6LR
MUST accept that registration if it is valid per [RFC6775], and it MUST accept that registration if it is valid per [RFC6775], and it
MUST manage the binding cache accordingly. The updated 6LR MUST then MUST manage the binding cache accordingly. The updated 6LR MUST then
use the RFC6775-only EDA messages as specified in [RFC6775] to use the RFC6775-only EDA messages as specified in [RFC6775] to
indicate to the 6LBR that the TID is not present in the messages. indicate to the 6LBR that the TID is not present in the messages.
The main difference from [RFC6775] is that the exchange of EDA The main difference from [RFC6775] is that the exchange of EDA
messages for the purpose of DAD is avoided for Link-Local Addresses. messages for the purpose of DAD is avoided for Link-Local Addresses.
In any case, the 6LR MUST use an EARO in the reply, and can use any In any case, the 6LR MUST use an EARO in the reply, and can use any
of the Status codes defined in this specification. of the Status codes defined in this specification.
6.4. RFC6775-only 6LoWPAN Router 6.3. RFC6775-only 6LoWPAN Router
An updated 6LN discovers the capabilities of the 6LR in the 6CIO in An updated 6LN discovers the capabilities of the 6LR in the 6CIO in
RA messages from that 6LR; if the 6CIO was not present in the RA, RA messages from that 6LR; if the 6CIO was not present in the RA,
then the 6LR is assumed to be a RFC6775-only 6LoWPAN Router. then the 6LR is assumed to be a RFC6775-only 6LoWPAN Router.
An updated 6LN MUST use an EARO in the request regardless of the type An updated 6LN MUST use an EARO in the request regardless of the type
of 6LR, RFC6775-only or updated, which implies that the 'T' flag is of 6LR, RFC6775-only or updated, which implies that the 'T' flag is
set. It MUST use a ROVR of 64 bits if the 6LR is an RFC6775-only set. It MUST use a ROVR of 64 bits if the 6LR is an RFC6775-only
6LoWPAN Router. 6LoWPAN Router.
skipping to change at page 25, line 8 skipping to change at page 25, line 27
the RFC6775-only 6LR will send an RFC6775-only DAR message, which the RFC6775-only 6LR will send an RFC6775-only DAR message, which
cannot be compared with an updated one for freshness. Allowing cannot be compared with an updated one for freshness. Allowing
RFC6775-only DAR messages to replace a state established by the RFC6775-only DAR messages to replace a state established by the
updated protocol in the 6LBR would be an attack vector and that updated protocol in the 6LBR would be an attack vector and that
cannot be the default behavior. But if RFC6775-only and updated 6LRs cannot be the default behavior. But if RFC6775-only and updated 6LRs
coexist temporarily in a network, then it makes sense for an coexist temporarily in a network, then it makes sense for an
administrator to install a policy that allows this, and the administrator to install a policy that allows this, and the
capability to install such a policy should be configurable in a 6LBR capability to install such a policy should be configurable in a 6LBR
though it is out of scope for this document. though it is out of scope for this document.
6.5. RFC6775-only 6LoWPAN Border Router 6.4. RFC6775-only 6LoWPAN Border Router
With this specification, the Duplicate Address messages are extended With this specification, the Duplicate Address messages are extended
to transport the EARO information. Similarly to the NS/NA exchange, to transport the EARO information. Similarly to the NS/NA exchange,
an updated 6LBR MUST always use the EDA messages. an updated 6LBR MUST always use the EDA messages.
Note that an RFC6775-only 6LBR will accept and process an EDAR Note that an RFC6775-only 6LBR will accept and process an EDAR
message as if it were an RFC6775-only DAR, as long as the ROVR is 64 message as if it were an RFC6775-only DAR, as long as the ROVR is 64
bits long. An updated 6LR discovers the capabilities of the 6LBR in bits long. An updated 6LR discovers the capabilities of the 6LBR in
the 6CIO in RA messages from the 6LR; if the 6CIO was not present in the 6CIO in RA messages from the 6LR; if the 6CIO was not present in
any RA, then the 6LBR si assumed to be a RFC6775-only 6LoWPAN Border any RA, then the 6LBR si assumed to be a RFC6775-only 6LoWPAN Border
Router. Router.
If the 6LBR is RFC6775-only, and the ROVR in the NS(EARO) was more If the 6LBR is RFC6775-only, and the ROVR in the NS(EARO) was more
than 64 bits long, then the 6LR MUST truncate the ROVR to the 64 than 64 bits long, then the 6LR MUST truncate the ROVR to the 64
rightmost bit and place the result in the EDAR message to maintain leftmost bits and place the result in the EDAR message to maintain
compatibility. This way, the support of DAD is preserved. compatibility. This way, the support of DAD is preserved.
7. Security Considerations 7. Security Considerations
This specification extends [RFC6775], and the security section of This specification extends [RFC6775], and the security section of
that document also applies to this as well. In particular, it is that document also applies to this as well. In particular, it is
expected that the link layer is sufficiently protected to prevent expected that the link layer is sufficiently protected to prevent
rogue access, either by means of physical or IP security on the rogue access, either by means of physical or IP security on the
Backbone Link and link-layer cryptography on the LLN. Backbone Link and link-layer cryptography on the LLN.
skipping to change at page 31, line 11 skipping to change at page 31, line 11
+-----------------+----------------------+-----------+ +-----------------+----------------------+-----------+
Table 6: New 6LoWPAN capability Bits Table 6: New 6LoWPAN capability Bits
10. Acknowledgments 10. Acknowledgments
Kudos to Eric Levy-Abegnoli who designed the First Hop Security Kudos to Eric Levy-Abegnoli who designed the First Hop Security
infrastructure upon which the first backbone router was implemented. infrastructure upon which the first backbone router was implemented.
Many thanks to Sedat Gormus, Rahul Jadhav, Tim Chown, Juergen Many thanks to Sedat Gormus, Rahul Jadhav, Tim Chown, Juergen
Schoenwaelder, Chris Lonvick, Dave Thaler, Adrian Farrel, Peter Yee, Schoenwaelder, Chris Lonvick, Dave Thaler, Adrian Farrel, Peter Yee,
Warren Kumari, Benjamin Kaduk, Mirja Kuhlewind, and Lorenzo Colitti Warren Kumari, Benjamin Kaduk, Mirja Kuhlewind, Ben Campbell, Eric
for their various contributions and reviews. Also, many thanks to Rescorla, and Lorenzo Colitti for their various contributions and
Thomas Watteyne for the world first implementation of a 6LN that was reviews. Also, many thanks to Thomas Watteyne for the world first
instrumental to the early tests of the 6LR, 6LBR and Backbone Router. implementation of a 6LN that was instrumental to the early tests of
the 6LR, 6LBR and Backbone Router.
11. References 11. References
11.1. Normative References 11.1. Normative References
[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/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
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