Internet DRAFT - draft-gomez-6lo-blemesh
draft-gomez-6lo-blemesh
6Lo Working Group C. Gomez
Internet-Draft S. Darroudi
Intended status: Standards Track UPC/i2cat
Expires: May 4, 2017 T. Savolainen
Nokia
October 31, 2016
IPv6 Mesh over Bluetooth(R) Low Energy using IPSP
draft-gomez-6lo-blemesh-02
Abstract
RFC 7668 describes the adaptation of 6LoWPAN techniques to enable
IPv6 over Bluetooth low energy networks that follow the star
topology. However, recent Bluetooth specifications allow the
formation of extended topologies as well. This document specifies
the mechanisms needed to enable IPv6 over mesh networks composed of
Bluetooth low energy links established by using the Bluetooth
Internet Protocol Support Profile.
Status of This Memo
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This Internet-Draft will expire on May 4, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology and Requirements Language . . . . . . . . . . 3
2. Bluetooth LE Networks and the IPSP . . . . . . . . . . . . . 3
3. Specification of IPv6 mesh over Bluetooth LE networks . . . . 3
3.1. Protocol stack . . . . . . . . . . . . . . . . . . . . . 4
3.2. Subnet model . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Link model . . . . . . . . . . . . . . . . . . . . . . . 5
3.3.1. Stateless address autoconfiguration . . . . . . . . . 5
3.3.2. Neighbor Discovery . . . . . . . . . . . . . . . . . 5
3.3.3. Header compression . . . . . . . . . . . . . . . . . 6
3.3.4. Unicast and multicast mapping . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Bluetooth low energy (hereinafter, Bluetooth LE) was first introduced
in the Bluetooth 4.0 specification. Bluetooth LE (which has been
marketed as Bluetooth Smart) is a low-power wireless technology
designed for short-range control and monitoring applications.
Bluetooth LE is currently implemented in a wide range of consumer
electronics devices, such as smartphones and wearable devices. Given
the high potential of this technology for the Internet of Things, the
Bluetooth Special Interest Group (Bluetooth SIG) and the IETF have
produced specifications in order to enable IPv6 over Bluetooth LE,
such as the Internet Protocol Support Profile (IPSP) [IPSP], and RFC
7668, respectively. Bluetooth 4.0 only supports Bluetooth LE
networks that follow the star topology. In consequence, RFC 7668 was
specifically developed and optimized for that type of network
topology. However, subsequent Bluetooth specifications allow the
formation of extended topologies [BTCorev4.1], such as the mesh
topology. The functionality described in RFC 7668 is not sufficient
and would fail to enable IPv6 over mesh networks composed of
Bluetooth LE links. This document specifies the mechanisms needed to
enable IPv6 over mesh networks composed of Bluetooth LE links. This
specification also allows to run IPv6 over Bluetooth LE star topology
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networks, albeit without all the topology-specific optimizations
contained in RFC 7668.
1.1. Terminology and Requirements Language
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].
The terms 6LoWPAN Node (6LN), 6LoWPAN Router (6LR) and 6LoWPAN Border
Router (6LBR) are defined as in [RFC6775], with an addition that
Bluetooth LE central and Bluetooth LE peripheral (see Section 2) can
both be adopted by a 6LN, a 6LR or a 6LBR.
2. Bluetooth LE Networks and the IPSP
Bluetooth LE defines two Generic Access Profile (GAP) roles of
relevance herein: the Bluetooth LE central role and the Bluetooth LE
peripheral role. A device in the central role, which is called
central from now on, has traditionally been able to manage multiple
simultaneous connections with a number of devices in the peripheral
role, called peripherals hereinafter. Bluetooth 4.1 introduced the
possibility for a peripheral to be connected to more than one central
simultaneously, therefore allowing extended topologies beyond the
star topology for a Bluetooth LE network. In addition, a device may
simultaneously be a central in a set of link layer connections, as
well as a peripheral in others. On the other hand, the IPSP enables
discovery of IP-enabled devices and the establishment of a link layer
connection for transporting IPv6 packets. The IPSP defines the Node
and Router roles for devices that consume/originate IPv6 packets and
for devices that can route IPv6 packets, respectively. Consistently
with Bluetooth 4.1, a device may implement both roles simultaneously.
This document assumes a mesh network composed of Bluetooth LE links,
where link layer connections have been established between
neighboring IPv6-enabled devices. The IPv6 forwarding devices of the
mesh have to implement both Node and Router roles, while simpler
leaf-only nodes can implement only the Node role. In an IPv6-enabled
mesh of Bluetooth LE links, a node is a neighbor of another node, and
vice versa, if a link layer connection has been established between
both by using the IPSP functionality for discovery and link layer
connection establishment for IPv6 packet transport.
3. Specification of IPv6 mesh over Bluetooth LE networks
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3.1. Protocol stack
Figure 1 illustrates the protocol stack for IPv6 mesh over Bluetooth
LE networks. There are two main differences with the IPv6 over
Bluetooth LE stack in RFC 7668: a) the adaptation layer below IPv6
(labelled as "6Lo for mesh of Bluetooth LE") is now adapted for mesh
networks of Bluetooth LE links, and b) the protocol stack for IPv6
mesh networks of Bluetooth LE links includes IPv6 routing
functionality.
+------------------------------------+
| Application |
+---------+ +------------------------------------+
| IPSS | | UDP/TCP/other |
+---------+ +------------------------------------+
| GATT | | IPv6 |routing| |
+---------+ +------------------------------------+
| ATT | | 6Lo for IPv6 mesh over Bluetooh LE |
+---------+--+------------------------------------+
| Bluetooth LE L2CAP |
- - +-------------------------------------------------+- - - HCI
| Bluetooth LE Link Layer |
+-------------------------------------------------+
| Bluetooth LE Physical |
+-------------------------------------------------+
Figure 1: Protocol stack for IPv6 mesh over Bluetooth LE.
3.2. Subnet model
For IPv6 mesh over Bluetooth LE, a multilink model has been chosen,
as further illustrated in Figure 2. As IPv6 over Bluetooth LE is
intended for constrained nodes, and for Internet of Things use cases
and environments, the complexity of implementing a separate subnet on
each peripheral-central link and routing between the subnets appears
to be excessive. In this specification, the benefits of treating the
collection of point-to-point links between a central and its
connected peripherals as a single multilink subnet rather than a
multiplicity of separate subnets are considered to outweigh the
multilink model's drawbacks as described in [RFC4903].
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/
.--------------------------------. /
/ 6LR 6LN 6LN \ /
/ \ \ \ \ /
| \ \ \ | /
| 6LN ----- 6LR --------- 6LR ------ 6LBR ----- | Internet
| <--Link--> <---Link--->/<--Link->/ | |
\ / / / \
\ 6LN ---- 6LR ----- 6LR / \
'--------------------------------' \
\
<------------ Subnet -----------------><---- IPv6 connection -->
to the Internet
Figure 2: Example of an IPv6 mesh over a Bluetooth LE network
connected to the Internet
One or more 6LBRs are connected to the Internet. 6LNs are connected
to the network through a 6LR or a 6LBR. A prefix is used on the
whole subnet.
IPv6 mesh networks over Bluetooth LE MUST follow a route-over
approach. This document does not specify the routing protocol to be
used in an IPv6 mesh over Bluetooth LE.
3.3. Link model
3.3.1. Stateless address autoconfiguration
6LN, 6LR and 6LBR IPv6 addresses in an IPv6 mesh over Bluetooth LE
are configured as per section 3.2.2 of RFC 7668.
Multihop DAD functionality as defined in section 8.2 of RFC 6775, or
some substitute mechanism (see section 3.3.2), MUST be supported.
3.3.2. Neighbor Discovery
'Neighbor Discovery Optimization for IPv6 over Low-Power Wireless
Personal Area Networks (6LoWPANs)' [RFC6775] describes the neighbor
discovery approach as adapted for use in several 6LoWPAN topologies,
including the mesh topology. The route-over functionality of RFC
6775 MUST be supported.
The following aspects of the Neighbor Discovery optimizations
[RFC6775] are applicable to Bluetooth LE 6LNs:
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1. A Bluetooth LE 6LN MUST NOT register its link-local address. A
Bluetooth LE 6LN MUST register its non-link-local addresses with its
routers by sending a Neighbor Solicitation (NS) message with the
Address Registration Option (ARO) and process the Neighbor
Advertisement (NA) accordingly. The NS with the ARO option MUST be
sent irrespective of the method used to generate the IID. The ARO
option requires use of an EUI-64 identifier [RFC6775]. In the case
of Bluetooth LE, the field SHALL be filled with the 48-bit device
address used by the Bluetooth LE node converted into 64-bit Modified
EUI-64 format [RFC4291].
If the 6LN registers for a same compression context multiple
addresses that are not based on Bluetooth device address, the header
compression efficiency will decrease.
2. For sending Router Solicitations and processing Router
Advertisements the Bluetooth LE 6LNs MUST, respectively, follow
Sections 5.3 and 5.4 of the [RFC6775].
3. The router behavior for 6LRs and 6LBRs is described in Section 6
of RFC 6775. However, as per this specification, routers SHALL NOT
use multicast NSs to discover other routers' link layer addresses.
4. Border router behavior is described in Section 7 of RFC 6775.
RFC 6775 defines substitutable mechanisms for distributing prefixes
and context information (section 8.1 of RFC 6775), as well as for
Duplicate Address Detection across a route-over 6LoWPAN (section 8.2
of RFC 6775). Implementations of this specification MUST support the
features described in sections 8.1 and 8.2 of RFC 6775 unless some
alternative ("substitute") from some other specification is
supported.
3.3.3. Header compression
Header compression as defined in RFC 6282 [RFC6282], which specifies
the compression format for IPv6 datagrams on top of IEEE 802.15.4, is
REQUIRED as the basis for IPv6 header compression on top of Bluetooth
LE. All headers MUST be compressed according to RFC 6282 [RFC6282]
encoding formats.
To enable efficient header compression, when the 6LBR sends a Router
Advertisement it MUST include a 6LoWPAN Context Option (6CO)
[RFC6775] matching each address prefix advertised via a Prefix
Information Option (PIO) [RFC4861] for use in stateless address
autoconfiguration.
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The specific optimizations of RFC 7668 for header compression, which
exploit the star topology and ARO, cannot be generalized in a mesh
network composed of Bluetooth LE links. Still, a subset of those
optimizations can be applied in some cases in such a network. In
particular, the latter comprise link-local interactions, non-link-
local packet transmissions originated and performed by a 6LN, and
non-link-local packet transmissions originated by a 6LN neighbor and
sent to a 6LN. For the rest of packet transmissions, context-based
compression MAY be used.
When a device transmits a packet to a neighbor, the sender MUST fully
elide the source IID if the source IPv6 address is the link-local
address based on the sender's Bluetooth device address (SAC=0,
SAM=11). The sender also MUST fully elide the destination IPv6
address if it is the link-local-address based on the neighbor's
Bluetooth device address (DAC=0, DAM=11).
When a 6LN transmits a packet, with a non-link-local source address
that the 6LN has registered with ARO in the next-hop router for the
indicated prefix, the source address MUST be fully elided if it is
the latest address that the 6LN has registered for the indicated
prefix (SAC=1, SAM=11). If the source non-link-local address is not
the latest registered by the 6LN, then the 64-bits of the IID SHALL
be fully carried in-line (SAC=1, SAM=01) or if the first 48-bits of
the IID match with the latest address registered by the 6LN, then the
last 16-bits of the IID SHALL be carried in-line (SAC=1, SAM=10).
When a router transmits a packet to a neighboring 6LN, with a non-
link-local destination address, the router MUST fully elide the
destination IPv6 address if the destination address is the latest
registered by the 6LN with ARO for the indicated context (DAC=1,
DAM=11). If the destination address is a non-link-local address and
not the latest registered, then the 6LN MUST either include the IID
part fully in-line (DAM=01) or, if the first 48-bits of the IID match
to the latest registered address, then elide those 48-bits (DAM=10).
3.3.4. Unicast and multicast mapping
The Bluetooth LE Link Layer does not support multicast. Hence,
traffic is always unicast between two Bluetooth LE neighboring nodes.
If a node needs to send a multicast packet to several neighbors, it
has to replicate the packet and unicast it on each link. However,
this may not be energy efficient, and particular care must be taken
if the node is battery powered. A router (i.e. a 6LR or a 6LBR) MUST
keep track of neighboring multicast listeners, and it MUST NOT
forward multicast packets to neighbors that have not registered as
listeners for multicast groups the packets belong to.
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4. IANA Considerations
There are no IANA considerations related to this document.
5. Security Considerations
The security considerations in RFC 7668 apply.
IPv6 mesh networks over Bluetooth LE require a routing protocol to
find end-to-end paths. Unfortunately, the routing protocol may
generate additional opportunities for threats and attacks to the
network.
RFC 7416 [RFC 7416] provides a systematic overview of threats and
attacks on the IPv6 Routing Protocol for Low-Power and Lossy Networks
(RPL), as well as countermeasures. In that document, described
threats and attacks comprise threats due to failures to authenticate,
threats due to failure to keep routing information, threats and
attacks on integrity, and threats and attacks on availability.
Reported countermeasures comprise confidentiality attack, integrity
attack, and availability attack countermeasures.
While this specification does not state the routing protocol to be
used in IPv6 mesh over Bluetooth LE networks, the guidance of RFC
7416 is useful when RPL is used in such scenarios. Furthermore, such
guidance may partly apply for other routing protocols as well.
6. Acknowledgements
The Bluetooth, Bluetooth Smart and Bluetooth Smart Ready marks are
registered trademarks owned by Bluetooth SIG, Inc.
The authors of this document are grateful to all RFC 7668 authors,
since this document borrows many concepts (albeit, with necessary
extensions) from RFC 7668.
The authors also thank Alain Michaud, Mark Powell and Martin Turon
for their comments, which helped improve the document.
Carles Gomez has been supported in part by the Spanish Government
Ministerio de Economia y Competitividad through project
TEC2012-32531, and FEDER.
7. References
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7.1. Normative References
[BTCorev4.1]
Bluetooth Special Interest Group, "Bluetooth Core
Specification Version 4.1", December 2013,
<https://www.bluetooth.org/en-us/specification/adopted-
specifications>.
[IPSP] Bluetooth Special Interest Group, "Bluetooth Internet
Protocol Support Profile Specification Version 1.0.0",
December 2014, <https://www.bluetooth.org/en-
us/specification/adopted-specifications>.
[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>.
[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>.
[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>.
[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>.
[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>.
7.2. Informative References
[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903,
DOI 10.17487/RFC4903, June 2007,
<http://www.rfc-editor.org/info/rfc4903>.
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[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
and M. Richardson, Ed., "A Security Threat Analysis for
the Routing Protocol for Low-Power and Lossy Networks
(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
<http://www.rfc-editor.org/info/rfc7416>.
Authors' Addresses
Carles Gomez
Universitat Politecnica de Catalunya/Fundacio i2cat
C/Esteve Terradas, 7
Castelldefels 08860
Spain
Email: carlesgo@entel.upc.edu
Seyed Mahdi Darroudi
Universitat Politecnica de Catalunya/Fundacio i2cat
C/Esteve Terradas, 7
Castelldefels 08860
Spain
Email: sm.darroudi@entel.upc.edu
Teemu Savolainen
Nokia Technologies
Hatanpaan valtatie 30
Tampere 33100
Finland
Email: teemu.savolainen@nokia.com
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