draft-ietf-6lo-blemesh-08.txt   draft-ietf-6lo-blemesh-09.txt 
6Lo Working Group C. Gomez 6Lo Working Group C. Gomez
Internet-Draft S. Darroudi Internet-Draft S. Darroudi
Intended status: Standards Track Universitat Politecnica de Catalunya Intended status: Standards Track Universitat Politecnica de Catalunya
Expires: April 10, 2021 T. Savolainen Expires: June 10, 2021 T. Savolainen
DarkMatter DarkMatter
M. Spoerk M. Spoerk
Graz University of Technology Graz University of Technology
October 7, 2020 December 7, 2020
IPv6 Mesh over BLUETOOTH(R) Low Energy using IPSP IPv6 Mesh over BLUETOOTH(R) Low Energy using IPSP
draft-ietf-6lo-blemesh-08 draft-ietf-6lo-blemesh-09
Abstract Abstract
RFC 7668 describes the adaptation of 6LoWPAN techniques to enable RFC 7668 describes the adaptation of 6LoWPAN techniques to enable
IPv6 over Bluetooth low energy networks that follow the star IPv6 over Bluetooth low energy networks that follow the star
topology. However, recent Bluetooth specifications allow the topology. However, recent Bluetooth specifications allow the
formation of extended topologies as well. This document specifies formation of extended topologies as well. This document specifies
mechanisms that are needed to enable IPv6 mesh over Bluetooth Low mechanisms that are needed to enable IPv6 mesh over Bluetooth Low
Energy links established by using the Bluetooth Internet Protocol Energy links established by using the Bluetooth Internet Protocol
Support Profile. This document does not specify the routing protocol Support Profile. This document does not specify the routing protocol
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 10, 2021. This Internet-Draft will expire on June 10, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology and Requirements Language . . . . . . . . . . 3 1.1. Terminology and Requirements Language . . . . . . . . . . 3
2. Bluetooth LE Networks and the IPSP . . . . . . . . . . . . . 3 2. Bluetooth LE Networks and the IPSP . . . . . . . . . . . . . 3
3. Specification of IPv6 mesh over Bluetooth LE links . . . . . 4 3. Specification of IPv6 mesh over Bluetooth LE links . . . . . 4
3.1. Protocol stack . . . . . . . . . . . . . . . . . . . . . 4 3.1. Protocol stack . . . . . . . . . . . . . . . . . . . . . 4
3.2. Subnet model . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Subnet model . . . . . . . . . . . . . . . . . . . . . . 5
3.3. Link model . . . . . . . . . . . . . . . . . . . . . . . 6 3.3. Link model . . . . . . . . . . . . . . . . . . . . . . . 6
3.3.1. Stateless address autoconfiguration . . . . . . . . . 6 3.3.1. Stateless address autoconfiguration . . . . . . . . . 6
3.3.2. Neighbor Discovery . . . . . . . . . . . . . . . . . 6 3.3.2. Neighbor Discovery . . . . . . . . . . . . . . . . . 6
3.3.3. Header compression . . . . . . . . . . . . . . . . . 7 3.3.3. Header compression . . . . . . . . . . . . . . . . . 8
3.3.4. Unicast and multicast mapping . . . . . . . . . . . . 8 3.3.4. Unicast and multicast mapping . . . . . . . . . . . . 9
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
8. Appendix A: Bluetooth LE connection establishment example . . 10 8. Appendix A: Bluetooth LE connection establishment example . . 11
9. Appendix B: Node joining procedure . . . . . . . . . . . . . 13 9. Appendix B: Node joining procedure . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1. Normative References . . . . . . . . . . . . . . . . . . 13 10.1. Normative References . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 14 10.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
Bluetooth Low Energy (hereinafter, Bluetooth LE) was first introduced Bluetooth Low Energy (hereinafter, Bluetooth LE) was first introduced
in the Bluetooth 4.0 specification. Bluetooth LE (which has been in the Bluetooth 4.0 specification. Bluetooth LE (which has been
marketed as Bluetooth Smart) is a low-power wireless technology marketed as Bluetooth Smart) is a low-power wireless technology
designed for short-range control and monitoring applications. designed for short-range control and monitoring applications.
Bluetooth LE is currently implemented in a wide range of consumer Bluetooth LE is currently implemented in a wide range of consumer
electronics devices, such as smartphones and wearable devices. Given electronics devices, such as smartphones and wearable devices. Given
the high potential of this technology for the Internet of Things, the the high potential of this technology for the Internet of Things, the
Bluetooth Special Interest Group (Bluetooth SIG) and the IETF have Bluetooth Special Interest Group (Bluetooth SIG) and the IETF have
produced specifications in order to enable IPv6 over Bluetooth LE, produced specifications in order to enable IPv6 over Bluetooth LE,
such as the Internet Protocol Support Profile (IPSP) [IPSP], and RFC such as the Internet Protocol Support Profile (IPSP) [IPSP], and RFC
7668, respectively. Bluetooth 4.0 only supports Bluetooth LE 7668 [RFC7668], respectively. Bluetooth 4.0 only supports Bluetooth
networks that follow the star topology. As a consequence, RFC 7668 LE networks that follow the star topology. As a consequence, RFC
was specifically developed and optimized for that type of network 7668 [RFC7668] was specifically developed and optimized for that type
topology. However, the functionality described in RFC 7668 is not of network topology. However, the functionality described in RFC
sufficient and would fail to enable an IPv6 mesh over Bluetooth LE 7668 [RFC7668] is not sufficient and would fail to enable an IPv6
links. This document specifies mechanisms that are needed to enable mesh over Bluetooth LE links. This document specifies mechanisms
IPv6 mesh over Bluetooth LE links. This document does not specify that are needed to enable IPv6 mesh over Bluetooth LE links. This
the routing protocol to be used in an IPv6 mesh over Bluetooth LE document does not specify the routing protocol to be used in an IPv6
links. mesh over Bluetooth LE links.
1.1. Terminology and Requirements Language 1.1. Terminology and Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in BCP14 RFC 2119
[RFC2119], RFC 8174 [RFC8174], when, and only when, they appear in
all capitals, as shown here.
The terms 6LoWPAN Node (6LN), 6LoWPAN Router (6LR) and 6LoWPAN Border The terms 6LoWPAN Node (6LN), 6LoWPAN Router (6LR) and 6LoWPAN Border
Router (6LBR) are defined as in [RFC6775], with an addition that Router (6LBR) are defined as in [RFC6775], with an addition that
Bluetooth LE central and Bluetooth LE peripheral (see Section 2) can Bluetooth LE central and Bluetooth LE peripheral (see Section 2) can
both be adopted by a 6LN, a 6LR or a 6LBR. both be adopted by a 6LN, a 6LR or a 6LBR.
2. Bluetooth LE Networks and the IPSP 2. Bluetooth LE Networks and the IPSP
Bluetooth LE defines two Generic Access Profile (GAP) roles of Bluetooth LE defines two Generic Access Profile (GAP) roles of
relevance herein: the Bluetooth LE central role and the Bluetooth LE relevance herein: the Bluetooth LE central role and the Bluetooth LE
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On the other hand, the IPSP enables discovery of IP-enabled devices On the other hand, the IPSP enables discovery of IP-enabled devices
and the establishment of a link layer connection for transporting and the establishment of a link layer connection for transporting
IPv6 packets. The IPSP defines the Node and Router roles for devices IPv6 packets. The IPSP defines the Node and Router roles for devices
that consume/originate IPv6 packets and for devices that can route that consume/originate IPv6 packets and for devices that can route
IPv6 packets, respectively. Consistently with Bluetooth 4.1 and IPv6 packets, respectively. Consistently with Bluetooth 4.1 and
subsequent Bluetooth versions (e.g. Bluetooth 4.2 [BTCorev4.2] or subsequent Bluetooth versions (e.g. Bluetooth 4.2 [BTCorev4.2] or
subsequent), a device may implement both roles simultaneously. subsequent), a device may implement both roles simultaneously.
This document assumes a mesh network composed of Bluetooth LE links, This document assumes a mesh network composed of Bluetooth LE links,
where link layer connections are established between neighboring where link layer connections are established between neighboring
IPv6-enabled devices (see Section 3.3.2, item 3.b)). The IPv6 IPv6-enabled devices (see Section 3.3.2, item 3.b, and an example in
forwarding devices of the mesh have to implement both IPSP Node and Appendix A)). The IPv6 forwarding devices of the mesh have to
Router roles, while simpler leaf-only nodes can implement only the implement both IPSP Node and Router roles, while simpler leaf-only
Node role. In an IPv6 mesh over Bluetooth LE links, a node is a nodes can implement only the Node role. In an IPv6 mesh over
neighbor of another node, and vice versa, if a link layer connection Bluetooth LE links, a node is a neighbor of another node, and vice
has been established between both by using the IPSP functionality for versa, if a link layer connection has been established between both
discovery and link layer connection establishment for IPv6 packet by using the IPSP functionality for discovery and link layer
transport. connection establishment for IPv6 packet transport.
3. Specification of IPv6 mesh over Bluetooth LE links 3. Specification of IPv6 mesh over Bluetooth LE links
3.1. Protocol stack 3.1. Protocol stack
Figure 1 illustrates the protocol stack for IPv6 mesh over Bluetooth Figure 1 illustrates the protocol stack for IPv6 mesh over Bluetooth
LE links. There are two main differences with the IPv6 over LE links. The core Bluetooth LE protocol stack comprises two main
Bluetooth LE stack in RFC 7668: a) the adaptation layer below IPv6 sections: the Controller, and the Host. The former includes the
(labelled as "6Lo for IPv6 mesh over Bluetooth LE") is now adapted Physical Layer, and the Link Layer, whereas the latter is composed of
for IPv6 mesh over Bluetooth LE links, and b) the protocol stack for the Logical Link Control and Adaptation Protocol (L2CAP), the
IPv6 mesh over Bluetooth LE links includes IPv6 routing Attribute Protocol (ATT), and the Generic Attribute Profile (GATT).
functionality. The Host and the Controller sections are connected by means of the
Host-Controller Interface (HCI). A device that supports the IPSP
Node role instantiates one Internet Protocol Support Service (IPSS),
which runs atop GATT. The protocol stack shown in Figure 1 shows two
main differences with the IPv6 over Bluetooth LE stack in RFC 7668:
a) the adaptation layer below IPv6 (labelled as "6Lo for IPv6 mesh
over Bluetooth LE") is now adapted for IPv6 mesh over Bluetooth LE
links, and b) the protocol stack for IPv6 mesh over Bluetooth LE
links includes IPv6 routing functionality.
+------------------------------------+ +------------------------------------+
| Application | | Application |
+---------+ +------------------------------------+ +---------+ +------------------------------------+
| IPSS | | UDP/TCP/other | | IPSS | | UDP/TCP/other |
+---------+ +------------------------------------+ +---------+ +------------------------------------+
| GATT | | IPv6 |routing| | | GATT | | IPv6 |routing| |
+---------+ +------------------------------------+ +---------+ +------------------------------------+
| ATT | | 6Lo for IPv6 mesh over Bluetooh LE | | ATT | | 6Lo for IPv6 mesh over Bluetooh LE |
+---------+--+------------------------------------+ +---------+--+------------------------------------+
| Bluetooth LE L2CAP | | Bluetooth LE L2CAP |
- - +-------------------------------------------------+- - - HCI HCI - - +-------------------------------------------------+ - -
| Bluetooth LE Link Layer | | Bluetooth LE Link Layer |
+-------------------------------------------------+ +-------------------------------------------------+
| Bluetooth LE Physical | | Bluetooth LE Physical Layer |
+-------------------------------------------------+ +-------------------------------------------------+
Figure 1: Protocol stack for IPv6 mesh over Bluetooth LE links. Figure 1: Protocol stack for IPv6 mesh over Bluetooth LE links.
Bluetooth 4.2 defines a default MTU for Bluetooth LE of 251 bytes. Bluetooth 4.2 defines a default MTU for Bluetooth LE of 251 bytes.
Excluding the L2CAP header of 4 bytes, a protocol data unit (PDU) Excluding the L2CAP header of 4 bytes, a protocol data unit (PDU)
size of 247 bytes is available for the layer above L2CAP. (Note: size of 247 bytes is available for the layer above L2CAP. (Note:
earlier Bluetooth LE versions offered a maximum amount of 23 bytes earlier Bluetooth LE versions offered a maximum amount of 23 bytes
for the layer atop L2CAP.) The L2CAP provides a fragmentation and for the layer atop L2CAP.) The L2CAP provides a fragmentation and
reassembly solution for transmitting or receiving larger PDUs. At reassembly solution for transmitting or receiving larger PDUs. At
each link, the IPSP defines means for negotiating a link-layer each link, the IPSP defines means for negotiating a link-layer
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For IPv6 mesh over Bluetooth LE links, a multilink model has been For IPv6 mesh over Bluetooth LE links, a multilink model has been
chosen, as further illustrated in Figure 2. As IPv6 over Bluetooth chosen, as further illustrated in Figure 2. As IPv6 over Bluetooth
LE is intended for constrained nodes, and for Internet of Things use LE is intended for constrained nodes, and for Internet of Things use
cases and environments, the complexity of implementing a separate cases and environments, the complexity of implementing a separate
subnet on each peripheral-central link and routing between the subnet on each peripheral-central link and routing between the
subnets appears to be excessive. In this specification, the benefits subnets appears to be excessive. In this specification, the benefits
of treating the collection of point-to-point links between a central of treating the collection of point-to-point links between a central
and its connected peripherals as a single multilink subnet rather and its connected peripherals as a single multilink subnet rather
than a multiplicity of separate subnets are considered to outweigh than a multiplicity of separate subnets are considered to outweigh
the multilink model's drawbacks as described in [RFC4903]. the multilink model's drawbacks as described in [RFC4903]. Note that
the route-over functionality defined in [RFC6775] is essential to
enable the multilink subnet model for IPv6 mesh over Bluetooth LE
links.
/ /
.--------------------------------. / .--------------------------------. /
/ 6LR 6LN 6LN \ / / 6LR 6LN 6LN \ /
/ \ \ \ \ / / \ \ \ \ /
| \ \ \ | / | \ \ \ | /
| 6LN ----- 6LR --------- 6LR ------ 6LBR ----- | Internet | 6LN ----- 6LR --------- 6LR ------ 6LBR ----- | Internet
| <--Link--> <---Link--->/<--Link->/ | | | <--Link--> <---Link--->/<--Link->/ | |
\ / / / \ \ / / / \
\ 6LN ---- 6LR ----- 6LR / \ \ 6LN ---- 6LR ----- 6LR / \
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prefix is used on the whole subnet. prefix is used on the whole subnet.
IPv6 mesh over Bluetooth LE links MUST follow a route-over approach. IPv6 mesh over Bluetooth LE links MUST follow a route-over approach.
This document does not specify the routing protocol to be used in an This document does not specify the routing protocol to be used in an
IPv6 mesh over Bluetooth LE links. IPv6 mesh over Bluetooth LE links.
3.3. Link model 3.3. Link model
3.3.1. Stateless address autoconfiguration 3.3.1. Stateless address autoconfiguration
6LN, 6LR and 6LBR IPv6 addresses in an IPv6 mesh over Bluetooth LE 6LN, 6LR, and 6LBR IPv6 addresses in an IPv6 mesh over Bluetooth LE
links are configured as per section 3.2.2 of RFC 7668. links are configured as per section 3.2.2 of RFC 7668.
Multihop DAD functionality as defined in section 8.2 of RFC 6775 and Multihop Duplicate Address Detection (DAD) functionality as defined
updated by RFC 8505, or some substitute mechanism (see section in section 8.2 of RFC 6775 and updated by RFC 8505, or some
3.3.2), MAY be supported. substitute mechanism (see section 3.3.2), MAY be supported.
3.3.2. Neighbor Discovery 3.3.2. Neighbor Discovery
'Neighbor Discovery Optimization for IPv6 over Low-Power Wireless 'Neighbor Discovery Optimization for IPv6 over Low-Power Wireless
Personal Area Networks (6LoWPANs)' [RFC6775], subsequently updated by Personal Area Networks (6LoWPANs)' [RFC6775], subsequently updated by
'Registration Extensions for IPv6 over Low-Power Wireless Personal 'Registration Extensions for IPv6 over Low-Power Wireless Personal
Area Network (6LoWPAN) Neighbor Discovery' [RFC8505], describes the Area Network (6LoWPAN) Neighbor Discovery' [RFC8505], describes the
neighbor discovery functionality adapted for use in several 6LoWPAN neighbor discovery functionality adapted for use in several 6LoWPAN
topologies, including the mesh topology. The route-over topologies, including the mesh topology. The route-over
functionality of RFC 6775 and RFC 8505 MUST be supported. functionality of RFC 6775 and RFC 8505 MUST be supported.
The following aspects of the Neighbor Discovery optimizations for The following aspects of the Neighbor Discovery optimizations for
6LoWPAN [RFC6775],[RFC8505] are applicable to Bluetooth LE 6LNs: 6LoWPAN [RFC6775],[RFC8505] are applicable to Bluetooth LE 6LNs:
1. A Bluetooth LE 6LN SHOULD register its non-link-local addresses 1. A Bluetooth LE 6LN SHOULD register its non-link-local addresses
with its routers by sending a Neighbor Solicitation (NS) message with with its routers by sending a Neighbor Solicitation (NS) message with
the Extended Address Registration Option (EARO) and process the the Extended Address Registration Option (EARO) and process the
Neighbor Advertisement (NA) accordingly. Note that in some cases Neighbor Advertisement (NA) accordingly. Note that in some cases
(e.g. very short-lived connections) it may not be worthwhile for a (e.g., very short-lived connections) it may not be worthwhile for a
6LN to send an NS with EARO for registering its address. The EARO 6LN to send an NS with EARO for registering its address. However,
option includes a Registration Ownership Verifier (ROVR) field the consequences of not registering the address (including non-
[RFC8505]. In the case of Bluetooth LE, by default the ROVR field is reachability of the 6LN, and absence of DAD) need to be carefully
filled with the 48-bit device address used by the Bluetooth LE node considered. The EARO option includes a Registration Ownership
converted into 64-bit Modified EUI-64 format [RFC4291]. Optionally, Verifier (ROVR) field [RFC8505]. In the case of Bluetooth LE, by
a cryptographic ID (see [I-D.ietf-6lo-ap-nd] MAY be placed in the default the ROVR field is filled with the 48-bit device address used
ROVR field. If a cryptographic ID is used, address registration and by the Bluetooth LE node converted into 64-bit Modified EUI-64 format
multihop DAD formats and procedures defined in [I-D.ietf-6lo-ap-nd] [RFC4291]. Optionally, a cryptographic ID (see RFC 8928 [RFC8928])
MUST be used, unless an alternative mechanism offering equivalent MAY be placed in the ROVR field. If a cryptographic ID is used,
protection is used. As per RFC 8505, a 6LN MUST NOT register its address registration and multihop DAD formats and procedures defined
link-local address. in RFC 8928 MUST be used, unless an alternative mechanism offering
equivalent protection is used. As per RFC 8505, a 6LN MUST NOT
register its link-local address.
If the 6LN registers multiple addresses that are not based on If the 6LN registers multiple addresses that are not based on the
Bluetooth device address using the same compression context, the Bluetooth device address using the same compression context, the
header compression efficiency will decrease. header compression efficiency may decrease, since only the last
registered address can be fully elided (see Section 3.2.4 of RFC
7668).
2. For sending Router Solicitations and processing Router 2. For sending Router Solicitations and processing Router
Advertisements the Bluetooth LE hosts MUST, respectively, follow Advertisements, the hosts that participate in an IPv6 mesh over BLE
Sections 5.3 and 5.4 of [RFC6775], and Section 5.6 of [RFC8505]. MUST, respectively, follow Sections 5.3 and 5.4 of [RFC6775], and
Section 5.6 of [RFC8505].
3. The router behavior for 6LRs and 6LBRs is described in Section 6 3. The router behavior for 6LRs and 6LBRs is described in Section 6
of RFC 6775, and updated by RFC 8505. However, as per this of RFC 6775, and updated by RFC 8505. However, as per this
specification: a) Routers SHALL NOT use multicast NSs to discover specification: a) Routers SHALL NOT use multicast NSs to discover
other routers' link layer addresses. b) As per section 6.2 of RFC other routers' link layer addresses. b) As per section 6.2 of RFC
6775, in a dynamic configuration scenario, a 6LR comes up as a non- 6775, in a dynamic configuration scenario, a 6LR comes up as a non-
router and waits to receive a Router Advertisement for configuring router and waits to receive a Router Advertisement for configuring
its own interface address first, before setting its interfaces to be its own interface address first, before setting its interfaces to be
advertising interfaces and turning into a router. In order to advertising interfaces and turning into a router. In order to
support such operation in an IPv6 mesh over Bluetooth LE links, a 6LR support such operation in an IPv6 mesh over Bluetooth LE links, a 6LR
first uses the IPSP Node role only. Once the 6LR has established a first uses the IPSP Node role only. Once the 6LR has established a
connection with another node currently running as a router, and connection with another node currently running as a router, and
receives a Router Advertisement from that router, the 6LR configures receives a Router Advertisement from that router, the 6LR configures
its own interface address, it turns into a router, and it runs as an its own interface address, it turns into a router, and it runs as an
IPSP Router. A 6LBR uses the IPSP Router role since the 6LBR is IPSP Router. In contrast with a 6LR, a 6LBR uses the IPSP Router
initialized. See an example in the Appendix. role since the 6LBR is initialized, that is, the 6LBR uses both the
IPSP Node and IPSP Router roles at all times. See an example in
Appendix B..
4. Border router behavior is described in Section 7 of RFC 6775, and 4. Border router behavior is described in Section 7 of RFC 6775, and
updated by RFC 8505. updated by RFC 8505.
RFC 6775 defines substitutable mechanisms for distributing prefixes RFC 6775 defines substitutable mechanisms for distributing prefixes
and context information (section 8.1 of RFC 6775), as well as for and context information (section 8.1 of RFC 6775), as well as for
Duplicate Address Detection across a route-over 6LoWPAN (section 8.2 Duplicate Address Detection across a route-over 6LoWPAN (section 8.2
of RFC 6775). RFC 8505 updates those mechanisms and the related of RFC 6775). RFC 8505 updates those mechanisms and the related
message formats. Implementations of this specification MAY support message formats. Implementations of this specification MUST either
the features described in sections 8.1 and 8.2 of RFC 6775, as support the features described in sections 8.1 and 8.2 of RFC 6775,
updated by RFC 8505, unless some alternative ("substitute") from some as updated by RFC 8505, or some alternative ("substitute") mechanism.
other specification is supported by the implementation.
3.3.3. Header compression 3.3.3. Header compression
Header compression as defined in RFC 6282 [RFC6282], which specifies Header compression as defined in RFC 6282 [RFC6282], which specifies
the compression format for IPv6 datagrams on top of IEEE 802.15.4, is 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 REQUIRED as the basis for IPv6 header compression on top of Bluetooth
LE. All headers MUST be compressed according to RFC 6282 [RFC6282] LE. All headers MUST be compressed according to RFC 6282 [RFC6282]
encoding formats. encoding formats.
To enable efficient header compression, when the 6LBR sends a Router To enable efficient header compression, when the 6LBR sends a Router
Advertisement it MAY include a 6LoWPAN Context Option (6CO) [RFC6775] Advertisement it MAY include a 6LoWPAN Context Option (6CO) [RFC6775]
matching each address prefix advertised via a Prefix Information matching each address prefix advertised via a Prefix Information
Option (PIO) [RFC4861] for use in stateless address Option (PIO) [RFC4861] for use in stateless address
autoconfiguration. Note that 6CO is not needed for context-based autoconfiguration. Note that 6CO is not needed for context-based
compression when a single prefix is used in the network. compression when context is pre-provisioned or provided by out-of-
band means.
The specific optimizations of RFC 7668 for header compression, which The specific optimizations of RFC 7668 for header compression, which
exploited the star topology and ARO (note that the latter has been exploited the star topology and ARO (note that the latter has been
updated by EARO as per RFC 8505), cannot be generalized in an IPv6 updated by EARO as per RFC 8505), cannot be generalized in an IPv6
mesh over Bluetooth LE links. Still, a subset of those optimizations mesh over Bluetooth LE links. Still, a subset of those optimizations
can be applied in some cases in such a network. These cases comprise can be applied in some cases in such a network. These cases comprise
link-local interactions, non-link-local packet transmissions link-local interactions, non-link-local packet transmissions
originated by a 6LN, and non-link-local packets intended for a 6LN originated by a 6LN (i.e. the first hop from a 6LN), and non-link-
that are originated or forwarded by a neighbor of that 6LN. For all local packets intended for a 6LN that are originated or forwarded by
a neighbor of that 6LN (i.e. the last hop toward a 6LN). For all
other packet transmissions, context-based compression MAY be used. other packet transmissions, context-based compression MAY be used.
When a device transmits a packet to a neighbor, the sender MUST fully 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 elide the source IID if the source IPv6 address is the link-local
address based on the sender's Bluetooth device address (SAC=0, address based on the sender's Bluetooth device address (SAC=0,
SAM=11). The sender also MUST fully elide the destination IPv6 SAM=11). The sender also MUST fully elide the destination IPv6
address if it is the link-local address based on the neighbor's address if it is the link-local address based on the neighbor's
Bluetooth device address (DAC=0, DAM=11). Bluetooth device address (DAC=0, DAM=11).
When a 6LN transmits a packet, with a non-link-local source address When a 6LN transmits a packet, with a non-link-local source address
that the 6LN has registered with EARO in the next-hop router for the that the 6LN has registered with EARO in the next-hop router for the
indicated prefix, the source address MUST be fully elided if it is indicated prefix, the source address MUST be fully elided if it is
the latest address that the 6LN has registered for the indicated 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 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 the latest registered by the 6LN, and the first 48 bits of the IID
be fully carried in-line (SAC=1, SAM=01) or if the first 48 bits of match with the latest address registered by the 6LN, then the last 16
the IID match with the latest address registered by the 6LN, then the bits of the IID SHALL be carried in-line (SAC=1, SAM=10). Otherwise,
last 16 bits of the IID SHALL be carried in-line (SAC=1, SAM=10). if the first 48 bits of the IID do not match, then the 64 bits of the
IID SHALL be fully carried in-line (SAC=1, SAM=01).
When a router transmits a packet to a neighboring 6LN, with a non- When a router transmits a packet to a neighboring 6LN, with a non-
link-local destination address, the router MUST fully elide the link-local destination address, the router MUST fully elide the
destination IPv6 address if the destination address is the latest destination IPv6 address if the destination address is the latest
registered by the 6LN with EARO for the indicated context (DAC=1, registered by the 6LN with EARO for the indicated context (DAC=1,
DAM=11). If the destination address is a non-link-local address and 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 not the latest registered, and the first 48 bits of the IID match to
part fully in-line (DAM=01) or, if the first 48 bits of the IID match those of the latest registered address, then the last 16 bits of the
to the latest registered address, then elide those 48 bits (DAM=10). IID SHALL be carried in-line (DAC=1, DAM=10). Otherwise, if the
first 48 bits of the IID do not match, then the 64 bits of the IID
SHALL be fully carried in-line (DAC=1, DAM=01).
3.3.4. Unicast and multicast mapping 3.3.4. Unicast and multicast mapping
The Bluetooth LE Link Layer does not support multicast. Hence, The Bluetooth LE Link Layer does not support multicast. Hence,
traffic is always unicast between two Bluetooth LE neighboring nodes. traffic is always unicast between two Bluetooth LE neighboring nodes.
If a node needs to send a multicast packet to several neighbors, it 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, has to replicate the packet and unicast it on each link. However,
this may not be energy efficient, and particular care must be taken 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 if the node is battery powered. A router (i.e., a 6LR or a 6LBR)
keep track of neighboring multicast listeners, and it MUST NOT MUST keep track of neighboring multicast listeners, and it MUST NOT
forward multicast packets to neighbors that have not registered as forward multicast packets to neighbors that have not registered as
listeners for multicast groups the packets belong to. listeners for multicast groups to which the packets are destined.
4. IANA Considerations 4. IANA Considerations
There are no IANA considerations related to this document. There are no IANA considerations related to this document.
5. Security Considerations 5. Security Considerations
The security considerations in RFC 7668 apply. The security considerations in RFC 7668 apply.
IPv6 mesh over Bluetooth LE links requires a routing protocol to find IPv6 mesh over Bluetooth LE links requires a routing protocol to find
end-to-end paths. Unfortunately, the routing protocol may generate end-to-end paths. Unfortunately, the routing protocol may generate
additional opportunities for threats and attacks to the network. additional opportunities for threats and attacks to the network.
RFC 7416 [RFC 7416] provides a systematic overview of threats and RFC 7416 [RFC7416] provides a systematic overview of threats and
attacks on the IPv6 Routing Protocol for Low-Power and Lossy Networks attacks on the IPv6 Routing Protocol for Low-Power and Lossy Networks
(RPL), as well as countermeasures. In that document, described (RPL), as well as countermeasures. In that document, described
threats and attacks comprise threats due to failures to authenticate, threats and attacks comprise threats due to failures to authenticate,
threats due to failure to keep routing information, threats and threats due to failure to keep routing information, threats and
attacks on integrity, and threats and attacks on availability. attacks on integrity, and threats and attacks on availability.
Reported countermeasures comprise confidentiality attack, integrity Reported countermeasures comprise confidentiality attack, integrity
attack, and availability attack countermeasures. attack, and availability attack countermeasures.
While this specification does not state the routing protocol to be While this specification does not state the routing protocol to be
used in IPv6 mesh over Bluetooth LE links, the guidance of RFC 7416 used in IPv6 mesh over Bluetooth LE links, the guidance of RFC 7416
is useful when RPL is used in such scenarios. Furthermore, such is useful when RPL is used in such scenarios. Furthermore, such
guidance may partly apply for other routing protocols as well. guidance may partly apply for other routing protocols as well.
The ROVR can be derived from the Bluetooth device address. However, The ROVR can be derived from the Bluetooth device address. However,
such a ROVR can be spoofed, and therefore, any node connected to the such a ROVR can be spoofed, and therefore, any node connected to the
subnet and aware of a registered-address-to-ROVR mapping could subnet and aware of a registered-address-to-ROVR mapping could
perform address theft and impersonation attacks. Use of Address perform address theft and impersonation attacks. Use of Address
Protected Neighbor Discovery [I-D.ietf-6lo-ap-nd] provides protection Protected Neighbor Discovery RFC 8928 [RFC8928] provides protection
against such attacks. against such attacks.
6. Contributors 6. Contributors
Carlo Alberto Boano (Graz University of Technology) contributed to Carlo Alberto Boano (Graz University of Technology) contributed to
the design and validation of this document. the design and validation of this document.
7. Acknowledgements 7. Acknowledgements
The Bluetooth, Bluetooth Smart and Bluetooth Smart Ready marks are The Bluetooth, Bluetooth Smart and Bluetooth Smart Ready marks are
registered trademarks owned by Bluetooth SIG, Inc. registered trademarks owned by Bluetooth SIG, Inc.
The authors of this document are grateful to all RFC 7668 authors, The authors of this document are grateful to all RFC 7668 authors,
since this document borrows many concepts (albeit, with necessary since this document borrows many concepts (albeit, with necessary
extensions) from RFC 7668. extensions) from RFC 7668.
The authors also thank Alain Michaud, Mark Powell, Martin Turon, The authors also thank Alain Michaud, Mark Powell, Martin Turon,
Bilhanan Silverajan, Rahul Jadhav and Pascal Thubert for their Bilhanan Silverajan, Rahul Jadhav, Pascal Thubert, Acee Lindem,
Catherine Meadows, and Dominique Barthel for their reviews and
comments, which helped improve the document. comments, which helped improve the document.
Carles Gomez has been supported in part by the Spanish Government Carles Gomez has been supported in part by the Spanish Government
Ministerio de Economia y Competitividad through projects Ministerio de Economia y Competitividad through projects
TEC2012-32531, TEC2016-79988-P and FEDER. TEC2012-32531, TEC2016-79988-P, PID2019-106808RA-I00 and FEDER, and
Secretaria d'Universitats i Recerca del Departament d'Empresa i
Coneixement de la Generalitat de Catalunya 2017 through grant SGR
376.
8. Appendix A: Bluetooth LE connection establishment example 8. Appendix A: Bluetooth LE connection establishment example
This appendix provides an example of Bluetooth LE connection This appendix provides an example of Bluetooth LE connection
establishment and use of IPSP roles in an IPv6 mesh over Bluetooth LE establishment and use of IPSP roles in an IPv6 mesh over Bluetooth LE
links that uses dynamic configuration. The example follows text in links that uses dynamic configuration. The example follows text in
Section 3.3.2, item 3.b). Section 3.3.2, item 3.b).
The example assumes a network with one 6LBR, two 6LRs and three 6LNs, The example assumes a network with one 6LBR, two 6LRs and three 6LNs,
as shown in Figure 3. Connectivity between the 6LNs and the 6LBR is as shown in Figure 3. Connectivity between the 6LNs and the 6LBR is
skipping to change at page 14, line 35 skipping to change at page 15, line 30
Bormann, "Neighbor Discovery Optimization for IPv6 over Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)", Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012, RFC 6775, DOI 10.17487/RFC6775, November 2012,
<https://www.rfc-editor.org/info/rfc6775>. <https://www.rfc-editor.org/info/rfc6775>.
[RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B., [RFC7668] Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015, Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
<https://www.rfc-editor.org/info/rfc7668>. <https://www.rfc-editor.org/info/rfc7668>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C. [RFC8505] Thubert, P., Ed., Nordmark, E., Chakrabarti, S., and C.
Perkins, "Registration Extensions for IPv6 over Low-Power Perkins, "Registration Extensions for IPv6 over Low-Power
Wireless Personal Area Network (6LoWPAN) Neighbor Wireless Personal Area Network (6LoWPAN) Neighbor
Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018, Discovery", RFC 8505, DOI 10.17487/RFC8505, November 2018,
<https://www.rfc-editor.org/info/rfc8505>. <https://www.rfc-editor.org/info/rfc8505>.
[RFC8928] Thubert, P., Ed., Sarikaya, B., Sethi, M., and R. Struik,
"Address-Protected Neighbor Discovery for Low-Power and
Lossy Networks", RFC 8928, DOI 10.17487/RFC8928, November
2020, <https://www.rfc-editor.org/info/rfc8928>.
10.2. Informative References 10.2. Informative References
[BTCorev4.1] [BTCorev4.1]
Bluetooth Special Interest Group, "Bluetooth Core Bluetooth Special Interest Group, "Bluetooth Core
Specification Version 4.1", December 2013, Specification Version 4.1", December 2013,
<https://www.bluetooth.org/en-us/specification/adopted- <https://www.bluetooth.org/en-us/specification/adopted-
specifications>. specifications>.
[I-D.ietf-6lo-ap-nd]
Thubert, P., Sarikaya, B., Sethi, M., and R. Struik,
"Address Protected Neighbor Discovery for Low-power and
Lossy Networks", draft-ietf-6lo-ap-nd-23 (work in
progress), April 2020.
[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, [RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903,
DOI 10.17487/RFC4903, June 2007, DOI 10.17487/RFC4903, June 2007,
<https://www.rfc-editor.org/info/rfc4903>. <https://www.rfc-editor.org/info/rfc4903>.
[RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A., [RFC7416] Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
and M. Richardson, Ed., "A Security Threat Analysis for and M. Richardson, Ed., "A Security Threat Analysis for
the Routing Protocol for Low-Power and Lossy Networks the Routing Protocol for Low-Power and Lossy Networks
(RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015, (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
<https://www.rfc-editor.org/info/rfc7416>. <https://www.rfc-editor.org/info/rfc7416>.
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