An Update to 6LoWPAN ND
draft-thubert-6lo-rfc6775-update-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|---|---|---|---|
| Authors | Pascal Thubert , Erik Nordmark , Samita Chakrabarti | ||
| Last updated | 2016-05-04 | ||
| Replaced by | draft-ietf-6lo-rfc6775-update, RFC 8505, draft-ietf-6lo-rfc6775-update | ||
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draft-thubert-6lo-rfc6775-update-00
6lo P. Thubert, Ed.
Internet-Draft cisco
Updates: 6775 (if approved) E. Nordmark
Intended status: Standards Track Arista Networks
Expires: November 5, 2016 S. Chakrabarti
Ericsson
May 4, 2016
An Update to 6LoWPAN ND
draft-thubert-6lo-rfc6775-update-00
Abstract
This specification proposes an update to 6LoWPAN Neighbor Discovery,
to clarify the role of the protocol as a registration technique, 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 November 5, 2016.
Copyright Notice
Copyright (c) 2016 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Extended Address Registration Option . . . . . . . . . . 4
3.2. Link-local Scope and Consequences . . . . . . . . . . . . 5
4. Applicability and Requirements Served . . . . . . . . . . . . 6
5. The Enhanced Address Registration Option (EARO) . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . 12
9.3. External Informative References . . . . . . . . . . . . . 15
Appendix A. Requirements . . . . . . . . . . . . . . . . . . . . 15
A.1. Requirements Related to Mobility . . . . . . . . . . . . 16
A.2. Requirements Related to Routing Protocols . . . . . . . . 16
A.3. Requirements Related to the Variety of Low-Power Link
types . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A.4. Requirements Related to Proxy Operations . . . . . . . . 18
A.5. Requirements Related to Security . . . . . . . . . . . . 18
A.6. Requirements Related to Scalability . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
The scope of this draft is an IPv6 Low Power Lossy Network (LLN),
which can be a simple star or a more complex mesh topology. The LLN
may be anchored at an IPv6 Backbone Router (6BBR). The Backbone
Routers interconnect the LLNs over a Backbone Link and emulate that
the LLN nodes are present on the Backbone using proxy-ND operations.
IPv6 Neighbor Discovery (ND) Optimization for IPv6 over Low-Power
Wireless Personal Area Networks(6LoWPANs) [RFC6775] introduced a
proactive registration mechanism to IPv6 ND services for nodes
belonging to a LLN.
This specification modifies and extends the behaviour and protocol
elements of [RFC6775] to enable additional capabilities, in
particular the registration to a 6BBR for proxy ND operations
[I-D.ietf-6lo-backbone-router].
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2. 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 [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
[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 BBR 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
[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.
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 SLLA in
the NS(ARO), or on behalf of a Registered Node that is
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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(ARO). 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.
3. Updating RFC 6775
The support of this specification is signaled in Router Advertisement
(RA) messages by 6LoWPAN Router (6LR) (how: tbd). A Registering Node
that supports this specification will favor registering to a 6LR that
indicates support for this specification over that of [RFC6775].
3.1. Extended Address Registration Option
This specification extends the Address Registration Option (ARO) 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 [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.
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3.2. Link-local Scope and Consequences
The use of link-local addresses as source address for the
registration, and the expectation for the scope of those addresses,
are clarified as follows:
A link is abstracted as a one-hop point-to-point communication
medium. There is no need nor expectation that a link-local address
is unique across the whole LLN. A 6LR assumes that the link-local
address of a Registering Node is unique as long as the 6LR does not
have a conflicting registration for that address.
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 link scope reachability from that 6LR beyond the
current exchange, and in particular to use it as Source Address to
register other addresses.
A consequence of this model is that the Duplicate Address Detection
(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 [RFC6775], does
not 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 as source for the NS(EARO) message.
When a Registering Node does not yet 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.
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 [RFC6775].
A node must register its IPv6 Global Unicast IPv6 Addresses (GUA) to
a 6LR in order to obtain a global reachability for these addresses
via that 6LR. In particular a Registering NODE registering a GUA
SHOULD NOT use that GUA as Source Address for the registration to a
6LR that conforms this specification.
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What makes this model practical in existing LLNs, which can grow to
large number of nodes, is that a subnet may encompass multiple links,
which can be LLN links or can be backbone links that federate a
number of LLN links, effectively forming a non-broadcast multi-access
(NBMA) multi-link subnet (MLSN).
4. Applicability and Requirements Served
This specification extends 6LoWPAN ND to sequence the registration
and serves the requirements expressed Appendix A.1 by enabling the
mobility of devices from one LLN to the next based on the
complementary work in [I-D.ietf-6lo-backbone-router].
In the context of the the TimeSlotted Channel Hopping (TSCH) mode of
[IEEE802154], 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 A.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, IEEE802.11AH and IEEE802.15.4 wireless meshes, so as to
address the requirements discussed in Appendix A.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 A.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 IEEE802.15.4
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 A.6.
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5. The Enhanced Address Registration Option (EARO)
With the ARO option defined in 6LoWPAN ND [RFC6775], the address
being registered and its owner can be uniquely identified and matched
with the Binding Table entries of each Backbone Router.
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 setting of the TID
bit. 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 TID bit and fields are reserved in [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 [RFC6775]. Once the router is known to
support this specification, the node MUST obey this specification.
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 [RFC6775] which specifies that the address being
registered is the source of the NS.
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. 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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One way of achieving all the above is for a node to first register an
address that it owns in order to validate that the router supports
this specification, placing the same address in the Source and Target
Address fields of the NS message. 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 older ND specifications such as ODAD [RFC4429].
Once that first registration is complete, the node knows from the
setting of the TID 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.
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 1: EARO
Option Fields
Type:
Length: 2
Status:
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+-------+-----------------------------------------------------------+
| Value | Description |
+-------+-----------------------------------------------------------+
| 0..2 | See [RFC6775]. Note that a Status of 1 "Duplicate |
| | Address" applies to the Registered Address. If the Source |
| | Address differs from the Registered Address it conflicts |
| | with an existing registration, "Invalid Source Address" |
| | should be used instead. |
| | |
| 3 | Moved: The registration fails because it is not the |
| | freshest. |
| | |
| 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 |
| | |
| 6 | Invalid Source Address: The address used as source of the |
| | NS(ARO) conflicts with an existing registration, or is |
| | not usable on this link, e.g. it is not topologically |
| | correct. |
| | |
| 7 | Administrative Rejection: The address is reserved for |
| | another use by an administrative decision (e.g. placed in |
| | a DHCPv6 pool). The Registering Node is requested to |
| | form a different address and retry. |
+-------+-----------------------------------------------------------+
Table 1
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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New status values are introduced, their values to be confirmed by
IANA:
Moved: 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.
Removed: 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. 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
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 ND ([RFC3971] and [RFC3972]) and
address privacy techniques. This specification RECOMMENDS the use of
additional protection against address theft such as provided by
[I-D.sarikaya-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.
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7. IANA Considerations
This document requires the following additions:
Address Registration Option Status Values Registry
+--------+--------------------------+
| Status | Description |
+--------+--------------------------+
| 3 | Moved |
| | |
| 4 | Removed |
| | |
| 5 | Proof requested |
| | |
| 6 | Invalid Source Address |
| | |
| 7 | Administrative Rejection |
+--------+--------------------------+
IANA is required to change the registry accordingly
Table 2: New ARO Status values
8. Acknowledgments
Kudos to Eric Levy-Abegnoli who designed the First Hop Security
infrastructure at Cisco.
9. References
9.1. Normative References
[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>.
[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>.
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[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>.
[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>.
9.2. 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-04 (work in progress), February 2016.
[I-D.ietf-6lo-backbone-router]
Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo-
backbone-router-01 (work in progress), March 2016.
[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-04 (work in progress),
February 2016.
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[I-D.ietf-6lo-nfc]
Hong, Y. and J. Youn, "Transmission of IPv6 Packets over
Near Field Communication", draft-ietf-6lo-nfc-03 (work in
progress), March 2016.
[I-D.ietf-6man-rs-refresh]
Nordmark, E., Yourtchenko, A., and S. Krishnan, "IPv6
Neighbor Discovery Optional RS/RA Refresh", draft-ietf-
6man-rs-refresh-01 (work in progress), March 2016.
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-09 (work
in progress), November 2015.
[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-07 (work in
progress), March 2016.
[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, A., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-03 (work in
progress), January 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.nordmark-6man-dad-approaches]
Nordmark, E., "Possible approaches to make DAD more robust
and/or efficient", draft-nordmark-6man-dad-approaches-02
(work in progress), October 2015.
[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.
[I-D.sarikaya-6lo-ap-nd]
Sarikaya, B. and P. Thubert, "Address Protected Neighbor
Discovery for Low-power and Lossy Networks", draft-
sarikaya-6lo-ap-nd-02 (work in progress), March 2016.
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[I-D.vyncke-6man-mcast-not-efficient]
Vyncke, E., Thubert, P., Levy-Abegnoli, E., and A.
Yourtchenko, "Why Network-Layer Multicast is Not Always
Efficient At Datalink Layer", draft-vyncke-6man-mcast-not-
efficient-01 (work in progress), February 2014.
[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>.
[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>.
[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>.
[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>.
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[RFC7559] Krishnan, S., Anipko, D., and D. Thaler, "Packet-Loss
Resiliency for Router Solicitations", RFC 7559,
DOI 10.17487/RFC7559, May 2015,
<http://www.rfc-editor.org/info/rfc7559>.
[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>.
[RFC7772] Yourtchenko, A. and L. Colitti, "Reducing Energy
Consumption of Router Advertisements", BCP 202, RFC 7772,
DOI 10.17487/RFC7772, February 2016,
<http://www.rfc-editor.org/info/rfc7772>.
9.3. External Informative References
[IEEE80211]
IEEE standard for Information Technology, "IEEE Standard
for Information technology-- Telecommunications and
information exchange between systems Local and
metropolitan area networks-- Specific requirements Part
11: Wireless LAN Medium Access Control (MAC) and Physical
Layer (PHY) Specifications".
[IEEE802151]
IEEE standard for Information Technology, "IEEE Standard
for Information Technology - Telecommunications and
Information Exchange Between Systems - Local and
Metropolitan Area Networks - Specific Requirements. - Part
15.1: Wireless Medium Access Control (MAC) and Physical
Layer (PHY) Specifications for Wireless Personal Area
Networks (WPANs)".
[IEEE802154]
IEEE standard for Information Technology, "IEEE Standard
for Local and metropolitan area networks-- Part 15.4: Low-
Rate Wireless Personal Area Networks (LR-WPANs)".
Appendix A. 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 A.5 which are deferred to a different
specification such as [I-D.sarikaya-6lo-ap-nd].
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A.1. Requirements Related to Mobility
Due to the unstable nature of LLN links, even in a LLN of immobile
nodes a 6LoWPAN Node 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.
A.2. Requirements Related to Routing Protocols
The point of attachment of a 6LoWPAN Node 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.
A.3. Requirements Related to the Variety of Low-Power Link types
6LoWPAN ND [RFC6775] was defined with a focus on IEEE802.15.4 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],
IEEE802.11ah [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 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].
A.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.
A.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 IEEE802.15.4 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 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.
A.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
Building D
45 Allee des Ormes - BP1200
MOUGINS - Sophia Antipolis 06254
FRANCE
Phone: +33 497 23 26 34
Email: pthubert@cisco.com
Erik Nordmark
Arista Networks
Santa Clara, CA
USA
Email: nordmark@arista.com
Samita Chakrabarti
Ericsson
San Jose, CA
USA
Email: samita.chakrabarti@ericsson.com
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