6lo P. Thubert, Ed.
Internet-Draft cisco
Updates: 6775, 7400 (if approved) E. Nordmark
Intended status: Standards Track
Expires: October 9, 2017 S. Chakrabarti
April 7, 2017
An Update to 6LoWPAN ND
draft-ietf-6lo-rfc6775-update-02
Abstract
This specification updates 6LoWPAN Neighbor Discovery (RFC 6775), to
clarify the role of the protocol as a registration technique,
simplify the registration operation in 6LoWPAN routers, and provide
enhancements to the registration capabilities, in particular for the
registration to a Backbone Router for proxy ND operations.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 9, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Considerations On Registration Rejection . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Updating RFC 7400 . . . . . . . . . . . . . . . . . . . . . . 5
5. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Transaction ID . . . . . . . . . . . . . . . . . . . . . 6
5.2. Owner Unique ID . . . . . . . . . . . . . . . . . . . . . 6
5.3. Extended Address Registration Option . . . . . . . . . . 7
5.4. Registering the Target Address . . . . . . . . . . . . . 7
5.5. Link-local Addresses and Registration . . . . . . . . . . 8
6. Updated ND Options . . . . . . . . . . . . . . . . . . . . . 9
6.1. New 6LoWPAN capability Bits in the Capability Indication
Option . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.2. The Enhanced Address Registration Option (EARO) . . . . . 10
7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 13
7.1. Discovering the capabilities of an ND peer . . . . . . . 13
7.1.1. Using the E Flag in the CIO . . . . . . . . . . . . . 13
7.1.2. Using the T Flag in the EARO . . . . . . . . . . . . 13
7.2. Legacy 6LoWPAN Node . . . . . . . . . . . . . . . . . . . 14
7.3. Legacy 6LoWPAN Router . . . . . . . . . . . . . . . . . . 14
7.4. Legacy 6LoWPAN Border Router . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
11.1. Normative References . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . 18
11.3. External Informative References . . . . . . . . . . . . 20
Appendix A. Applicability and Requirements Served . . . . . . . 20
Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 21
B.1. Requirements Related to Mobility . . . . . . . . . . . . 22
B.2. Requirements Related to Routing Protocols . . . . . . . . 22
B.3. Requirements Related to the Variety of Low-Power Link
types . . . . . . . . . . . . . . . . . . . . . . . . . . 23
B.4. Requirements Related to Proxy Operations . . . . . . . . 24
B.5. Requirements Related to Security . . . . . . . . . . . . 24
B.6. Requirements Related to Scalability . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
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1. Introduction
RFC 6775, the "Neighbor Discovery Optimization for IPv6 over Low-
Power Wireless Personal Area Networks (6LoWPANs)" [RFC6775]
introduced a proactive registration mechanism to IPv6 Neighbor
Discovery (ND) services that is well suited to nodes belonging to a
Low Power Lossy Network (LLN).
The scope of this draft is an IPv6 LLN, which can be a simple star or
a more complex mesh topology. The LLN may be anchored at an IPv6
Backbone Router (6BBR) [I-D.ietf-6lo-backbone-router]. The 6BBRs
interconnect the LLNs over a Backbone Link and emulate that the LLN
nodes are present on the Backbone using proxy-ND operations.
This specification modifies and extends the behaviour and protocol
elements of RFC 6775 [RFC6775] to enable additional capabilities, in
particular the registration to a 6BBR for proxy ND operations.
2. Considerations On Registration Rejection
The purpose of the Address Registration Option (ARO) RFC 6775
[RFC6775] and of the Extended ARO (EARO) that is introduced in this
document is to facilitate duplicate address detection (DAD) for hosts
and pre-populate Neighbor Cache Entries (NCE) [RFC4861] in the
routers to reduce the need for sending multicast neighbor
solicitations and also to be able to support IPv6 Backbone Routers.
In some cases the address registration can fail or be useless for
reasons other than a duplicate address. Examples are the router
having run out of space, a registration bearing a stale sequence
number (e.g. denoting a movement of the host after this registration
was placed), a host misbehaving and attempting to register an invalid
address such as the unspecified address [RFC4291], or the host using
an address which is not topologically correct on that link. In such
cases the host will receive an error to help diagnose the issue and
may retry, possibly with a different address, and possibly
registering to a different 6LR, depending on the returned error.
However, the ability to return errors to address registrations MUST
NOT be used to restrict the ability of hosts to form and use
addresses as recommended in "Host Address Availability
Recommendations" [RFC7934]. In particular, this is needed for
enhanced privacy, which implies that each host will register a
multiplicity of address as part mechanisms like "Privacy Extensions
for Stateless Address Autoconfiguration (SLAAC) in IPv6" [RFC4941].
This implies that a 6LR or 6LBR which is intended to support N hosts
MUST have space to register at least on the order of 10N IPv6
addresses.
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3. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Readers are expected to be familiar with all the terms and concepts
that are discussed in
"Neighbor Discovery for IP version 6" [RFC4861],
"IPv6 Stateless Address Autoconfiguration" [RFC4862],
"IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals" [RFC4919],
"Neighbor Discovery Optimization for Low-power and Lossy Networks"
[RFC6775] and
"Multi-link Subnet Support in IPv6"
[I-D.ietf-ipv6-multilink-subnets].
Additionally, this document uses terminology from
"Terms Used in Routing for Low-Power and Lossy Networks" [RFC7102]
and
the "6TiSCH Terminology" [I-D.ietf-6tisch-terminology],
as well as this additional terminology:
Backbone This is an IPv6 transit link that interconnects 2 or more
Backbone Routers. It is expected to be deployed as a high
speed backbone in order to federate a potentially large set of
LLNS. Also referred to as a LLN backbone or Backbone network.
Backbone Router An IPv6 router that federates the LLN using a
Backbone link as a backbone. A 6BBR acts as a 6LoWPAN Border
Routers (6LBR) and an Energy Aware Default Router (NEAR).
Extended LLN This is the aggregation of multiple LLNs as defined in
RFC 4919 [RFC4919], interconnected by a Backbone Link via
Backbone Routers, and forming a single IPv6 MultiLink Subnet.
Registration The process during which a wireless Node registers its
address(es) with the Border Router so the 6BBR can proxy ND for
it over the backbone.
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Binding The state in the 6BBR that associates an IP address with a
MAC address, a port and some other information about the node
that owns the IP address.
Registered Node The node for which the registration is performed,
which owns the fields in the EARO option.
Registering Node The node that performs the registration to the
6BBR, either for one of its own addresses, in which case it is
Registered Node and indicates its own MAC Address as Source
Link Layer Address (SLLA) in the NS(EARO), or on behalf of a
Registered Node that is reachable over a LLN mesh. In the
latter case, if the Registered Node is reachable from the 6BBR
over a Mesh-Under mesh, the Registering Node indicates the MAC
Address of the Registered Node as SLLA in the NS(EARO).
Otherwise, it is expected that the Registered Device is
reachable over a Route-Over mesh from the Registering Node, in
which case the SLLA in the NS(ARO) is that of the Registering
Node, which causes it to attract the packets from the 6BBR to
the Registered Node and route them over the LLN.
Registered Address The address owned by the Registered Node node
that is being registered.
4. Updating RFC 7400
RFC 7400 [RFC7400] introduces the 6LoWPAN Capability Indication
Option (6CIO) to indicate a node's capabilities to its peers. This
specification extends the format defined in RFC 7400 to signal the
support for EARO, as well as the capability to act as a 6LR, 6LBR and
6BBR.
With RFC 7400 [RFC7400], the 6CIO is typically sent Router
Solicitation (RS) messages. When used to signal the capabilities
above per this specification, the 6CIO is typically present Router
Advertisement (RA) messages but can also be present in RS, Neighbor
Solicitation (NS) and Neighbor Advertisement (NA) messages.
5. Updating RFC 6775
This specification extends the Address Registration Option (ARO)
defined in RFC 6775 [RFC6775]; in particular a "T" flag is added that
must be set is NS messages when this specification is used, and
echo'ed in NA messages to confirm that the protocol effectively
supported. Support for this specification can thus be inferred from
the presence of the Extended ARO ("T" flag set) in ND messages.
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A Registering Node that supports this specification will favor
registering to a 6LR that indicates support for this specification
over that of RFC 6775 [RFC6775].
5.1. Transaction ID
The specification expects that the Registered Node can provide a
sequence number called Transaction ID (TID) that is incremented with
each re-registration. The TID essentially obeys the same rules as
the Path Sequence field in the Transit Information Option (TIO) found
in RPL's Destination Advertisement Object (DAO). This way, the LLN
node can use the same counter for ND and RPL, and a 6LBR acting as
RPL root may easily maintain the registration on behalf of a RPL node
deep inside the mesh by simply using the RPL TIO Path Sequence as TID
for EARO.
When a Registered Node is registered to multiple BBRs in parallel, it
is expected that the same TID is used, to enable the 6BBRs to
correlate the registrations as being a single one, and differentiate
that situation from a movement.
If the TIDs are different, the resolution inherited from RPL sorts
out the most recent registration and other ones are removed. The
operation for computing and comparing the Path Sequence is detailed
in section 7 of RFC 6550 [RFC6550] and applies to the TID in the
exact same fashion.
5.2. Owner Unique ID
The Owner Unique ID (OUID) enables to differentiate a real duplicate
address registration from a double registration or a movement. An ND
message from the 6BBR over the backbone that is proxied on behalf of
a Registered Node must carry the most recent EARO option seen for
that node. A NS/NA with an EARO and a NS/NA without a EARO thus
represent different nodes and if they relate to a same target then
they reflect an address duplication. The Owner Unique ID can be as
simple as a EUI-64 burn-in address, if duplicate EUI-64 addresses are
avoided.
Alternatively, the unique ID can be a cryptographic string that can
can be used to prove the ownership of the registration as discussed
in "Address Protected Neighbor Discovery for Low-power and Lossy
Networks" [I-D.ietf-6lo-ap-nd].
In any fashion, it is recommended that the node stores the unique Id
or the keys used to generate that ID in persistent memory.
Otherwise, it will be prevented to re-register after a reboot that
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would cause a loss of memory until the Backbone Router times out the
registration.
5.3. Extended Address Registration Option
This specification extends the ARO option that is used for the
process of address registration. The new ARO is referred to as
Extended ARO (EARO), and its semantics are modified as follows:
The address that is being registered with a Neighbor Solicitation
(NS) with an EARO is now the Target Address, as opposed to the Source
Address as specified in RFC 6775 [RFC6775]. This change enables a
6LBR to use an address of his as source to the proxy-registration of
an address that belongs to a LLN Node to a 6BBR. This also limits
the use of an address as source address before it is registered and
the associated Duplicate Address Detection (DAD) is complete.
The Unique ID in the EARO option does no more have to be a MAC
address. A new TLV format is introduced and a IANA registry is
created for the type (TBD). This enables in particular the use of a
Provable Temporary UID (PT-UID) as opposed to burn-in MAC address,
the PT-UID providing a trusted anchor by the 6LR and 6LBR to protect
the state associated to the node.
The specification introduces a Transaction ID (TID) field in the
EARO. The TID MUST be provided by a node that supports this
specification and a new T flag MUST be set to indicate so. The T bit
can be used to determine whether the peer supports this
specification.
5.4. Registering the Target Address
This specification changes the behaviour 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 opposed to the Source Address.
The reason for this change is to enable proxy-registrations on behalf
of other nodes in Route-Over meshes, for instance to enable that a
RPL root registers addresses on behalf LLN nodes that are deeper in a
6TiSCH mesh, as discussed in Appendix B.4. In that case, the
Registering Node MUST indicate its own address as source of the ND
message and its MAC address in the Source Link-Layer Address Option
(SLLAO), since it still expects to get the packets and route them
down the mesh. But the Registered Address belongs to another node,
the Registered Node, and that address is indicated in the Target
Address field of the NS message.
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With this convention, a TLLA option indicates the link-layer address
of the 6LN that owns the address, whereas the SLLA Option in a NS
message indicates that of the Registering Node, which can be the
owner device, or a proxy.
Since the Registering Node is the one that has reachability with the
6LR, and is the one expecting packets for the 6LN, it makes sense to
maintain compatibility with RFC 6775 [RFC6775], and it is REQUIRED
that an SLLA Option is always placed in a registration NS(EARO)
message.
5.5. Link-local Addresses and Registration
Considering that LLN nodes are often not wired and may move, there is
no guarantee that a link-local address stays unique between a
potentially variable and unbounded set of neighboring nodes.
Compared to RFC 6775 [RFC6775], this specification only requires that
a link-local address is unique from the perspective of the peering
nodes. This simplifies the Duplicate Address Detection (DAD) for
link-local addresses, and there is no DAR/DAC exchange between the
6LR and a 6LBR for link-local addresses.
Additionally, RFC 6775 [RFC6775] requires that a 6LoWPAN Node (6LN)
uses an address being registered as the source of the registration
message. This generates complexities in the 6LR to be able to cope
with a potential duplication, in particular for global addresses. To
simplify this, a 6LN and a 6LR that conform this specification always
use link-local addresses as source and destination addresses for the
registration NS/NA exchange. As a result, the registration is
globally faster, and some of the complexity is removed.
In more details:
An exchange between two nodes using link-local addresses implies that
they are reachable over one hop and that at least one of the 2 nodes
acts as a 6LR. A node MUST register a link-local 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 as source
address to register other addresses, e.g. global addresses.
If there is no collision with an address previously registered to
this 6LR by another 6LN, then, from the standpoint of this 6LR, this
link-local address is unique and the registration is acceptable.
Conversely, it may possibly happen that two different 6LRs expose a
same link-local address but different link-layer addresses. In that
case, a 6LN may only interact with one of the 6LR so as to avoid
confusion in the 6LN neighbor cache.
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The DAD process between the 6LR and a 6LoWPAN Border Router (6LBR),
which is based on a Duplicate Address Request (DAR) / Duplicate
Address Confirmation (DAC) exchange as described in RFC 6775
[RFC6775], does not need to take place for link-local addresses.
It is desired that a 6LR does not need to modify its state associated
to the Source Address of an NS(EARO) message. For that reason, when
possible, it is RECOMMENDED to use an address that is already
registered with a 6LR
When registering to a 6LR that conforms this specification, a node
MUST use a link-local address as the source address of the
registration, whatever the type of IPv6 address that is being
registered. That link-local Address MUST be either already
registrered, or the address that is being registered.
When a Registering Node does not have an already-registered address,
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
RECOMMENDED to use a link-local address that is (expected to be)
globally unique, e.g. derived from a burn-in MAC address. An EARO
option in the response NA indicates that the 6LR supports this
specification.
Since there is no DAR/DAC exchange for link-local addresses, the 6LR
may answer immediately to the registration of a link-local address,
based solely on its existing state and the Source Link-Layer Option
that MUST be placed in the NS(EARO) message as required in RFC 6775
[RFC6775].
A node needs to register its IPv6 Global Unicast IPv6 Addresses (GUA)
to a 6LR in order to obtain a global reachability for these addresses
via that 6LR. As opposed to a node that complies to RFC 6775
[RFC6775], a Registering Node registering a GUA does not use that GUA
as Source Address for the registration to a 6LR that conforms this
specification. The DAR/DAC exchange MUST take place for non-link-
local addresses as prescribed by RFC 6775 [RFC6775].
6. Updated ND Options
This specification does not introduce new options, but it modifies
existing ones and updates the associated behaviours as follow:
6.1. New 6LoWPAN capability Bits in the Capability Indication Option
This specification defines a number of capability bits in the CIO
that was introduced by RFC 7400 [RFC7400].
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Support for this specification is indicated by setting the "E" flag
in a CIO option. Routers that are capable of acting as 6LR, 6LBR and
6BBR SHOULD set the L, B andP flags, respectively.
Those flags are not mutually exclusive and if a router is capable of
multiple roles, it SHOULD set all the related flags.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 1 |_____________________|L|B|P|E|G|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|_______________________________________________________________|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: New capability Bits L, B, P, E in the CIO
Option Fields
Type: 36
L: Node is a 6LR, it can take registrations.
B: Node is a 6LBR.
P: Node is a 6BBR, proxying for nodes on this link.
E: This specification is supported and applied.
6.2. The Enhanced Address Registration Option (EARO)
The Enhanced Address Registration Option (EARO) is intended to be
used as a replacement to the ARO option within Neighbor Discovery NS
and NA messages between a LLN node and its 6LoWPAN Router (6LR), as
well as in Duplicate Address Request (DAR) and the Duplicate Address
Confirmation (DAC) messages between 6LRs and 6LBRs in LLNs meshes
such as 6TiSCH networks.
An NS message with an EARO option is a registration if and only if it
also carries an SLLAO option. The AERO option also used in NS and NA
messages between Backbone Routers over the backbone link to sort out
the distributed registration state, and in that case, it does not
carry the SLLAO option and is not confused with a registration.
The EARO extends the ARO and is recognized by the "T" flag set.
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When using the EARO option, the address being registered is found in
the Target Address field of the NS and NA messages. This differs
from 6LoWPAN ND RFC 6775 [RFC6775] which specifies that the address
being registered is the source of the NS.
The format of the EARO option is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 2 | Status | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |T| TID | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Owner Unique ID (EUI-64 or equivalent) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: EARO
Option Fields
Type: 33
Length: 8-bit unsigned integer.
Status: 8-bit unsigned integer. Indicates the status of a
registration in the NA response. MUST be set to 0 in NS messages.
See Table 1 below.
Reserved: This field is unused. It MUST be initialized to zero by
the sender and MUST be ignored by the receiver.
T: One bit flag. Set if the next octet is a used as a TID.
TID: 1-byte integer; a transaction id that is maintained by the node
and incremented with each transaction. it is recommended that the
node maintains the TID in a persistent storage.
Registration Lifetime: 16-bit integer; expressed in minutes. 0
means that the registration has ended and the state should be
removed.
Owner Unique Identifier (OUI): A globally unique identifier for the
node associated. This can be the EUI-64 derived IID of an
interface, or some provable ID obtained cryptographically.
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+-------+-----------------------------------------------------------+
| Value | Description |
+-------+-----------------------------------------------------------+
| 0..2 | See RFC 6775 [RFC6775]. Note that a Status of 1 |
| | "Duplicate Address" applies to the Registered Address. If |
| | the Source Address conflicts with an existing |
| | registration, "Duplicate Source Address" should be used |
| | instead |
| | |
| 3 | Moved: The registration fails because it is not the |
| | freshest. This status indicates that the registration is |
| | rejected because another more recent registration was |
| | done, as indicated by a same OUI and a more recent TID. |
| | One possible cause is a stale registration that has |
| | progressed slowly in the network and was passed by a more |
| | recent one. It could also indicate a OUI collision. |
| | |
| 4 | Removed: The binding state was removed. This may be |
| | placed in an asynchronous NS(ARO) message, or as the |
| | rejection of a proxy registration to a Backbone Router |
| | |
| 5 | Proof requested: The registering node is challenged for |
| | owning the registered address or for being an acceptable |
| | proxy for the registration. This status is expected in |
| | asynchronous messages from a registrar (6LR, 6LBR, 6BBR) |
| | to indicate that the registration state is removed, for |
| | instance due to time out of a lifetime, or a movement. It |
| | is used for instance by a 6BBR in a NA(ARO) message to |
| | indicate that the ownership of the proxy state on the |
| | backbone was transfered to another 6BBR, which is |
| | indicative of a movement of the device. The receiver of |
| | the NA is the device that has performed a registration |
| | that is now stale and it should clean up its state. |
| | |
| 6 | Duplicate Source Address: The address used as source of |
| | the NS(ARO) conflicts with an existing registration. |
| | |
| 7 | Invalid Source Address: The address used as source of the |
| | NS(ARO) is not usable on this link, e.g. it is not |
| | topologically correct |
| | |
| 8 | Invalid Registered Address: The address being registered |
| | is not usable on this link, e.g. it is not topologically |
| | correct |
+-------+-----------------------------------------------------------+
Table 1: EARO Status
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7. Backward Compatibility
7.1. Discovering the capabilities of an ND peer
7.1.1. Using the E Flag in the CIO
If the CIO is used in an ND message, then the "E" Flag MUST be set by
the sending node if supports this specification.
It is RECOMMENDED that a router that supports this specification
indicates so with a CIO option, but this might not be practical if
the link-layer MTU is too small.
If the registering node receives a CIO in a RA, then the setting of
the E" Flag indicates whether or not this specification is supported.
7.1.2. Using the T Flag in the EARO
One alternate way for a 6LN to discover the router's capabilities to
first register a Link Local address, placing the same address in the
Source and Target Address fields of the NS message, and setting the
"T" Flag. The node may for instance register an address that is
based on EUI-64. For such address, DAD is not required and using the
SLLAO option in the NS is actually more amenable with existing ND
specifications such as the "Optimistic Duplicate Address Detection
(DAD) for IPv6" [RFC4429]. Once that first registration is complete,
the node knows from the setting of the "T" Flag in the response
whether the router supports this specification. If this is verified,
the node may register other addresses that it owns, or proxy-register
addresses on behalf some another node, indicating those addresses
being registered in the Target Address field of the NS messages,
while using one of its own, already registered, addresses as source.
A node that supports this specification MUST always use an EARO as a
replacement to an ARO in its registration to a router. This is
harmless since the "T" flag and TID field are reserved in RFC 6775
[RFC6775] are ignored by a legacy router. A router that supports
this specification answers to an ARO with an ARO and to an EARO with
an EARO.
This specification changes the behavior of the peers in a
registration flows. To enable backward compatibility, a node that
registers to a router that is not known to support this specification
MUST behave as prescribed by RFC 6775 [RFC6775]. Once the router is
known to support this specification, the node MUST obey this
specification.
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7.2. Legacy 6LoWPAN Node
A legacy 6LN will use the registered address as source and will not
use an EARO option. In order to be backward compatible, an updated
6LR needs to accept that registration if it is valid per the
"Cryptographically Generated Addresses (CGA)" [RFC3972]
specification, and manage the binding cache accordingly.
The main difference with RFC 3972 [RFC3972] is that DAR/DAC exchange
for DAD may be avoided for link-local addresses. Additionally, the
6LR SHOULD use an EARO in the reply, and may use any of the status
codes defined in this specification.
7.3. Legacy 6LoWPAN Router
The first registration by a an updated 6LN is for a link-local
address, using that link-local address as source. A legacy 6LN will
not makes a difference and accept -or reject- that registration as if
the 6LN was a legacy node.
An updated 6LN will always use an EARO option in the registration NS
message, whereas a legacy 6LN will always areply with an ARO option
in the NA message. So from that first registration, the updated 6LN
can figure whether the 6LR supports this specification or not.
When facing a legacy 6LR, an updated 6LN may attempt to find an
alternate 6LR that is updated. In order to be backward compatible,
based on the discovery that a 6LR is legacy, the 6LN needs to
fallback to legacy behaviour and source the packet with the
registrered address.
The main difference is that the updated 6LN SHOULD use an EARO in the
request regardless of the type of 6LN, legacy or updated
7.4. Legacy 6LoWPAN Border Router
With this specification, the DAR/DAC transports an EARO option as
opposed to an ARO option. As described for the NS/NA exchange,
devices that support this specification always use an EARO option and
all the associated behaviour.
8. Security Considerations
This specification expects that the link layer is sufficiently
protected, either by means of physical or IP security for the
Backbone Link or MAC sublayer cryptography. In particular, it is
expected that the LLN MAC provides secure unicast to/from the
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Backbone Router and secure Broadcast from the Backbone Router in a
way that prevents tempering with or replaying the RA messages.
The use of EUI-64 for forming the Interface ID in the link-local
address prevents the usage of "SEcure Neighbor Discovery (SEND)"
[RFC3971] and CGA [RFC3972], and that of address privacy techniques.
This specification RECOMMENDS the use of additional protection
against address theft such as provided by "Address Protected Neighbor
Discovery for Low-power and Lossy Networks" [I-D.ietf-6lo-ap-nd],
which guarantees the ownership of the OUID.
When the ownership of the OUID cannot be assessed, this specification
limits the cases where the OUID and the TID are multicasted, and
obfuscates them in responses to attempts to take over an address.
The LLN nodes depend on the 6LBR and the 6BBR for their operation. A
trust model must be put in place to ensure that the right devices are
acting in these roles, so as to avoid threats such as black-holing,
or bombing attack whereby an impersonated 6LBR would destroy state in
the network by using the "Removed" status code.
9. IANA Considerations
IANA is requested to create a new subregistry for "ARO Flags" under
the "Internet Control Message Protocol version 6 (ICMPv6)
Parameters". This specification defines 8 positions, bit 0 to bit 7,
and assigns bit 7 for the "T" flag in Section 6.2. The policy is
"IETF Review" or "IESG Approval" [RFC5226]. The initial content of
the registry is as shown in Table 2.
New subregistry for ARO Flags under the "Internet Control Message
Protocol version 6 (ICMPv6) Parameters"
+------------+--------------+-----------+
| ARO Status | Description | Document |
+------------+--------------+-----------+
| 0..6 | Unassigned | |
| | | |
| 7 | "T" Flag | RFC This |
+------------+--------------+-----------+
Table 2: new ARO Flags
IANA is requested to make additions to existing registries as
follows:
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Address Registration Option Status Values Registry
+------------+----------------------------+-----------+
| ARO Status | Description | Document |
+------------+----------------------------+-----------+
| 3 | Moved | RFC This |
| | | |
| 4 | Removed | RFC This |
| | | |
| 5 | Proof requested | RFC This |
| | | |
| 6 | Duplicate Source Address | RFC This |
| | | |
| 7 | Invalid Source Address | RFC This |
| | | |
| 8 | Invalid Registered Address | RFC This |
+------------+----------------------------+-----------+
Table 3: New ARO Status values
Subregistry for "6LoWPAN capability Bits" under the "Internet Control
Message Protocol version 6 (ICMPv6) Parameters"
+----------------+----------------------+-----------+
| capability Bit | Description | Document |
+----------------+----------------------+-----------+
| 11 | 6LR capable (L bit) | RFC This |
| | | |
| 12 | 6LBR capable (B bit) | RFC This |
| | | |
| 13 | 6BBR capable (P bit) | RFC This |
| | | |
| 14 | EARO support (E bit) | RFC This |
+----------------+----------------------+-----------+
Table 4: New 6LoWPAN capability Bits
10. Acknowledgments
Kudos to Eric Levy-Abegnoli who designed the First Hop Security
infrastructure at Cisco.
11. References
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11.1. Normative References
[I-D.ietf-6lo-backbone-router]
Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo-
backbone-router-03 (work in progress), January 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
[RFC4429] Moore, N., "Optimistic Duplicate Address Detection (DAD)
for IPv6", RFC 4429, DOI 10.17487/RFC4429, April 2006,
<http://www.rfc-editor.org/info/rfc4429>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<http://www.rfc-editor.org/info/rfc4941>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<http://www.rfc-editor.org/info/rfc6282>.
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[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012,
<http://www.rfc-editor.org/info/rfc6550>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<http://www.rfc-editor.org/info/rfc6775>.
[RFC7400] Bormann, C., "6LoWPAN-GHC: Generic Header Compression for
IPv6 over Low-Power Wireless Personal Area Networks
(6LoWPANs)", RFC 7400, DOI 10.17487/RFC7400, November
2014, <http://www.rfc-editor.org/info/rfc7400>.
[RFC7934] Colitti, L., Cerf, V., Cheshire, S., and D. Schinazi,
"Host Address Availability Recommendations", BCP 204,
RFC 7934, DOI 10.17487/RFC7934, July 2016,
<http://www.rfc-editor.org/info/rfc7934>.
11.2. Informative References
[I-D.chakrabarti-nordmark-6man-efficient-nd]
Chakrabarti, S., Nordmark, E., Thubert, P., and M.
Wasserman, "IPv6 Neighbor Discovery Optimizations for
Wired and Wireless Networks", draft-chakrabarti-nordmark-
6man-efficient-nd-07 (work in progress), February 2015.
[I-D.delcarpio-6lo-wlanah]
Vega, L., Robles, I., and R. Morabito, "IPv6 over
802.11ah", draft-delcarpio-6lo-wlanah-01 (work in
progress), October 2015.
[I-D.ietf-6lo-6lobac]
Lynn, K., Martocci, J., Neilson, C., and S. Donaldson,
"Transmission of IPv6 over MS/TP Networks", draft-ietf-
6lo-6lobac-08 (work in progress), March 2017.
[I-D.ietf-6lo-ap-nd]
Sarikaya, B., Thubert, P., and M. Sethi, "Address
Protected Neighbor Discovery for Low-power and Lossy
Networks", draft-ietf-6lo-ap-nd-00 (work in progress),
November 2016.
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[I-D.ietf-6lo-dect-ule]
Mariager, P., Petersen, J., Shelby, Z., Logt, M., and D.
Barthel, "Transmission of IPv6 Packets over DECT Ultra Low
Energy", draft-ietf-6lo-dect-ule-09 (work in progress),
December 2016.
[I-D.ietf-6lo-nfc]
Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi,
"Transmission of IPv6 Packets over Near Field
Communication", draft-ietf-6lo-nfc-06 (work in progress),
March 2017.
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-11 (work
in progress), January 2017.
[I-D.ietf-6tisch-terminology]
Palattella, M., Thubert, P., Watteyne, T., and Q. Wang,
"Terminology in IPv6 over the TSCH mode of IEEE
802.15.4e", draft-ietf-6tisch-terminology-08 (work in
progress), December 2016.
[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-05 (work in
progress), October 2016.
[I-D.ietf-ipv6-multilink-subnets]
Thaler, D. and C. Huitema, "Multi-link Subnet Support in
IPv6", draft-ietf-ipv6-multilink-subnets-00 (work in
progress), July 2002.
[I-D.popa-6lo-6loplc-ipv6-over-ieee19012-networks]
Popa, D. and J. Hui, "6LoPLC: Transmission of IPv6 Packets
over IEEE 1901.2 Narrowband Powerline Communication
Networks", draft-popa-6lo-6loplc-ipv6-over-
ieee19012-networks-00 (work in progress), March 2014.
[RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with
CBC-MAC (CCM)", RFC 3610, DOI 10.17487/RFC3610, September
2003, <http://www.rfc-editor.org/info/rfc3610>.
[RFC3810] Vida, R., Ed. and L. Costa, Ed., "Multicast Listener
Discovery Version 2 (MLDv2) for IPv6", RFC 3810,
DOI 10.17487/RFC3810, June 2004,
<http://www.rfc-editor.org/info/rfc3810>.
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[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005,
<http://www.rfc-editor.org/info/rfc3971>.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, DOI 10.17487/RFC3972, March 2005,
<http://www.rfc-editor.org/info/rfc3972>.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007,
<http://www.rfc-editor.org/info/rfc4919>.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, DOI 10.17487/RFC7102, January
2014, <http://www.rfc-editor.org/info/rfc7102>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>.
[RFC7428] Brandt, A. and J. Buron, "Transmission of IPv6 Packets
over ITU-T G.9959 Networks", RFC 7428,
DOI 10.17487/RFC7428, February 2015,
<http://www.rfc-editor.org/info/rfc7428>.
[RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
<http://www.rfc-editor.org/info/rfc7668>.
11.3. External Informative References
[IEEEstd802154]
IEEE, "IEEE Standard for Low-Rate Wireless Networks",
IEEE Standard 802.15.4,
<http://ieeexplore.ieee.org/document/7460875/>.
Appendix A. Applicability and Requirements Served
This specification extends 6LoWPAN ND to sequence the registration
and serves the requirements expressed Appendix B.1 by enabling the
mobility of devices from one LLN to the next based on the
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complementary work in the "IPv6 Backbone Router"
[I-D.ietf-6lo-backbone-router] specification.
In the context of the the TimeSlotted Channel Hopping (TSCH) mode of
IEEE Std. 802.15.4 [IEEEstd802154], the "6TiSCH architecture"
[I-D.ietf-6tisch-architecture] introduces how a 6LoWPAN ND host could
connect to the Internet via a RPL mesh Network, but this requires
additions to the 6LOWPAN ND protocol to support mobility and
reachability in a secured and manageable environment. This
specification details the new operations that are required to
implement the 6TiSCH architecture and serves the requirements listed
in Appendix B.2.
The term LLN is used loosely in this specification to cover multiple
types of WLANs and WPANs, including Low-Power Wi-Fi, BLUETOOTH(R) Low
Energy, IEEE std 802.11AH and IEEE std 802.15.4 wireless meshes, so
as to address the requirements discussed in Appendix B.3
This specification can be used by any wireless node to associate at
Layer-3 with a 6BBR and register its IPv6 addresses to obtain routing
services including proxy-ND operations over the backbone, effectively
providing a solution to the requirements expressed in Appendix B.4.
"Efficiency aware IPv6 Neighbor Discovery Optimizations"
[I-D.chakrabarti-nordmark-6man-efficient-nd] suggests that 6LoWPAN ND
[RFC6775] can be extended to other types of links beyond IEEE Std.
802.15.4 for which it was defined. The registration technique is
beneficial when the Link-Layer technique used to carry IPv6 multicast
packets is not sufficiently efficient in terms of delivery ratio or
energy consumption in the end devices, in particular to enable
energy-constrained sleeping nodes. The value of such extension is
especially apparent in the case of mobile wireless nodes, to reduce
the multicast operations that are related to classical ND ([RFC4861],
[RFC4862]) and plague the wireless medium. This serves scalability
requirements listed in Appendix B.6.
Appendix B. Requirements
This section lists requirements that were discussed at 6lo for an
update to 6LoWPAN ND. This specification meets most of them, but
those listed in Appendix B.5 which are deferred to a different
specification such as [I-D.ietf-6lo-ap-nd], and those related to
multicast.
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B.1. Requirements Related to Mobility
Due to the unstable nature of LLN links, even in a LLN of immobile
nodes a 6LN may change its point of attachment to a 6LR, say 6LR-a,
and may not be able to notify 6LR-a. Consequently, 6LR-a may still
attract traffic that it cannot deliver any more. When links to a 6LR
change state, there is thus a need to identify stale states in a 6LR
and restore reachability in a timely fashion.
Req1.1: Upon a change of point of attachment, connectivity via a new
6LR MUST be restored timely without the need to de-register from the
previous 6LR.
Req1.2: For that purpose, the protocol MUST enable to differentiate
between multiple registrations from one 6LoWPAN Node and
registrations from different 6LoWPAN Nodes claiming the same address.
Req1.3: Stale states MUST be cleaned up in 6LRs.
Req1.4: A 6LoWPAN Node SHOULD also be capable to register its Address
to multiple 6LRs, and this, concurrently.
B.2. Requirements Related to Routing Protocols
The point of attachment of a 6LN may be a 6LR in an LLN mesh. IPv6
routing in a LLN can be based on RPL, which is the routing protocol
that was defined at the IETF for this particular purpose. Other
routing protocols than RPL are also considered by Standard Defining
Organizations (SDO) on the basis of the expected network
characteristics. It is required that a 6LoWPAN Node attached via ND
to a 6LR would need to participate in the selected routing protocol
to obtain reachability via the 6LR.
Next to the 6LBR unicast address registered by ND, other addresses
including multicast addresses are needed as well. For example a
routing protocol often uses a multicast address to register changes
to established paths. ND needs to register such a multicast address
to enable routing concurrently with discovery.
Multicast is needed for groups. Groups MAY be formed by device type
(e.g. routers, street lamps), location (Geography, RPL sub-tree), or
both.
The Bit Index Explicit Replication (BIER) Architecture
[I-D.ietf-bier-architecture] proposes an optimized technique to
enable multicast in a LLN with a very limited requirement for routing
state in the nodes.
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Related requirements are:
Req2.1: The ND registration method SHOULD be extended in such a
fashion that the 6LR MAY advertise the Address of a 6LoWPAN Node over
the selected routing protocol and obtain reachability to that Address
using the selected routing protocol.
Req2.2: Considering RPL, the Address Registration Option that is used
in the ND registration SHOULD be extended to carry enough information
to generate a DAO message as specified in [RFC6550] section 6.4, in
particular the capability to compute a Path Sequence and, as an
option, a RPLInstanceID.
Req2.3: Multicast operations SHOULD be supported and optimized, for
instance using BIER or MPL. Whether ND is appropriate for the
registration to the 6BBR is to be defined, considering the additional
burden of supporting the Multicast Listener Discovery Version 2
[RFC3810] (MLDv2) for IPv6.
B.3. Requirements Related to the Variety of Low-Power Link types
6LoWPAN ND [RFC6775] was defined with a focus on IEEE std 802.15.4
and in particular the capability to derive a unique Identifier from a
globally unique MAC-64 address. At this point, the 6lo Working Group
is extending the 6LoWPAN Header Compression (HC) [RFC6282] technique
to other link types ITU-T G.9959 [RFC7428], Master-Slave/Token-
Passing [I-D.ietf-6lo-6lobac], DECT Ultra Low Energy
[I-D.ietf-6lo-dect-ule], Near Field Communication [I-D.ietf-6lo-nfc],
IEEE std 802.11ah [I-D.delcarpio-6lo-wlanah], as well as IEEE1901.2
Narrowband Powerline Communication Networks
[I-D.popa-6lo-6loplc-ipv6-over-ieee19012-networks] and BLUETOOTH(R)
Low Energy [RFC7668].
Related requirements are:
Req3.1: The support of the registration mechanism SHOULD be extended
to more LLN links than IEEE std 802.15.4, matching at least the LLN
links for which an "IPv6 over foo" specification exists, as well as
Low-Power Wi-Fi.
Req3.2: As part of this extension, a mechanism to compute a unique
Identifier should be provided, with the capability to form a Link-
Local Address that SHOULD be unique at least within the LLN connected
to a 6LBR discovered by ND in each node within the LLN.
Req3.3: The Address Registration Option used in the ND registration
SHOULD be extended to carry the relevant forms of unique Identifier.
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Req3.4: The Neighbour Discovery should specify the formation of a
site-local address that follows the security recommendations from
[RFC7217].
B.4. Requirements Related to Proxy Operations
Duty-cycled devices may not be able to answer themselves to a lookup
from a node that uses classical ND on a backbone and may need a
proxy. Additionally, the duty-cycled device may need to rely on the
6LBR to perform registration to the 6BBR.
The ND registration method SHOULD defend the addresses of duty-cycled
devices that are sleeping most of the time and not capable to defend
their own Addresses.
Related requirements are:
Req4.1: The registration mechanism SHOULD enable a third party to
proxy register an Address on behalf of a 6LoWPAN node that may be
sleeping or located deeper in an LLN mesh.
Req4.2: The registration mechanism SHOULD be applicable to a duty-
cycled device regardless of the link type, and enable a 6BBR to
operate as a proxy to defend the registered Addresses on its behalf.
Req4.3: The registration mechanism SHOULD enable long sleep
durations, in the order of multiple days to a month.
B.5. Requirements Related to Security
In order to guarantee the operations of the 6LoWPAN ND flows, the
spoofing of the 6LR, 6LBR and 6BBRs roles should be avoided. Once a
node successfully registers an address, 6LoWPAN ND should provide
energy-efficient means for the 6LBR to protect that ownership even
when the node that registered the address is sleeping.
In particular, the 6LR and the 6LBR then should be able to verify
whether a subsequent registration for a given Address comes from the
original node.
In a LLN it makes sense to base security on layer-2 security. During
bootstrap of the LLN, nodes join the network after authorization by a
Joining Assistant (JA) or a Commissioning Tool (CT). After joining
nodes communicate with each other via secured links. The keys for
the layer-2 security are distributed by the JA/CT. The JA/CT can be
part of the LLN or be outside the LLN. In both cases it is needed
that packets are routed between JA/CT and the joining node.
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Related requirements are:
Req5.1: 6LoWPAN ND security mechanisms SHOULD provide a mechanism for
the 6LR, 6LBR and 6BBR to authenticate and authorize one another for
their respective roles, as well as with the 6LoWPAN Node for the role
of 6LR.
Req5.2: 6LoWPAN ND security mechanisms SHOULD provide a mechanism for
the 6LR and the 6LBR to validate new registration of authorized
nodes. Joining of unauthorized nodes MUST be impossible.
Req5.3: 6LoWPAN ND security mechanisms SHOULD lead to small packet
sizes. In particular, the NS, NA, DAR and DAC messages for a re-
registration flow SHOULD NOT exceed 80 octets so as to fit in a
secured IEEE std 802.15.4 [IEEEstd802154] frame.
Req5.4: Recurrent 6LoWPAN ND security operations MUST NOT be
computationally intensive on the LoWPAN Node CPU. When a Key hash
calculation is employed, a mechanism lighter than SHA-1 SHOULD be
preferred.
Req5.5: The number of Keys that the 6LoWPAN Node needs to manipulate
SHOULD be minimized.
Req5.6: The 6LoWPAN ND security mechanisms SHOULD enable the
variation of CCM [RFC3610] called CCM* for use at both Layer 2 and
Layer 3, and SHOULD enable the reuse of security code that has to be
present on the device for upper layer security such as TLS.
Req5.7: Public key and signature sizes SHOULD be minimized while
maintaining adequate confidentiality and data origin authentication
for multiple types of applications with various degrees of
criticality.
Req5.8: Routing of packets should continue when links pass from the
unsecured to the secured state.
Req5.9: 6LoWPAN ND security mechanisms SHOULD provide a mechanism for
the 6LR and the 6LBR to validate whether a new registration for a
given address corresponds to the same 6LoWPAN Node that registered it
initially, and, if not, determine the rightful owner, and deny or
clean-up the registration that is duplicate.
B.6. Requirements Related to Scalability
Use cases from Automatic Meter Reading (AMR, collection tree
operations) and Advanced Metering Infrastructure (AMI, bi-directional
communication to the meters) indicate the needs for a large number of
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LLN nodes pertaining to a single RPL DODAG (e.g. 5000) and connected
to the 6LBR over a large number of LLN hops (e.g. 15).
Related requirements are:
Req6.1: The registration mechanism SHOULD enable a single 6LBR to
register multiple thousands of devices.
Req6.2: The timing of the registration operation should allow for a
large latency such as found in LLNs with ten and more hops.
Authors' Addresses
Pascal Thubert (editor)
Cisco Systems, Inc
Sophia Antipolis
FRANCE
Email: pthubert@cisco.com
Erik Nordmark
Santa Clara, CA
USA
Email: nordmark@sonic.net
Samita Chakrabarti
San Jose, CA
USA
Email: samitac.ietf@gmail.com
Thubert, et al. Expires October 9, 2017 [Page 26]