6LoWPAN Working Group J. Nieminen, Ed.
Internet-Draft T. Savolainen, Ed.
Intended status: Standards Track M. Isomaki
Expires: August 16, 2013 Nokia
B. Patil
Z. Shelby
Sensinode
C. Gomez
Universitat Politecnica de
Catalunya/i2CAT
February 12, 2013
Transmission of IPv6 Packets over BLUETOOTH Low Energy
draft-ietf-6lowpan-btle-12
Abstract
BLUETOOTH Low Energy is a low power air interface technology defined
by the BLUETOOTH Special Interest Group (BT-SIG). The standard
BLUETOOTH radio has been widely implemented and available in mobile
phones, notebook computers, audio headsets and many other devices.
The low power version of BLUETOOTH is a new specification that
enables the use of this air interface with devices such as sensors,
smart meters, appliances, etc. The low power variant of BLUETOOTH is
currently specified in the revision 4.0 of the BLUETOOTH
specifications (BLUETOOTH 4.0). This document describes how IPv6 is
transported over BLUETOOTH Low Energy using 6LoWPAN techniques.
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 August 16, 2013.
Copyright Notice
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Copyright (c) 2013 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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology and Requirements Language . . . . . . . . . . 3
2. BLUETOOTH Low Energy . . . . . . . . . . . . . . . . . . . . . 3
2.1. BLUETOOTH Low Energy stack . . . . . . . . . . . . . . . . 4
2.2. Link layer roles and topology . . . . . . . . . . . . . . 4
2.3. BT-LE device addressing . . . . . . . . . . . . . . . . . 5
2.4. BT-LE packets sizes and MTU . . . . . . . . . . . . . . . 5
3. Specification of IPv6 over BLUETOOTH Low Energy . . . . . . . 6
3.1. Protocol stack . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Link model . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1. Stateless address autoconfiguration . . . . . . . . . 8
3.2.2. Neighbor discovery . . . . . . . . . . . . . . . . . . 9
3.2.3. Header compression . . . . . . . . . . . . . . . . . . 9
3.2.4. Unicast and Multicast address mapping . . . . . . . . 10
3.3. Internet connectivity scenarios . . . . . . . . . . . . . 11
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. Additional contributors . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. BLUETOOTH Low Energy fragmentation and L2CAP Modes . 14
Appendix B. BLUETOOTH Low Energy L2CAP Channel ID Usage for
6LoWPAN/IPv6 . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
BLUETOOTH Low Energy (BT-LE) is a radio technology targeted for
devices that operate with coin cell batteries or minimalistic power
sources, which means that low power consumption is essential. BT-LE
is an especially attractive technology for Internet of Things
applications, such as health monitors, environmental sensing,
proximity applications and many others.
Considering the potential for the exponential growth in the number of
sensors and Internet connected devices and things, IPv6 is an ideal
protocol due to the large address space it provides. In addition,
IPv6 provides tools for stateless address autoconfiguration, which is
particularly suitable for sensor network applications and nodes which
have very limited processing power or lack a full-fledged operating
system.
RFC 4944 [RFC4944] specifies the transmission of IPv6 over IEEE
802.15.4. The BT-LE link in many respects has similar
characteristics to that of IEEE 802.15.4. Many of the mechanisms
defined in the RFC 4944 can be applied to the transmission of IPv6 on
BT-LE links. This document specifies the details of IPv6
transmission over BT-LE links.
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 6LN, 6LR and 6LBR are defined as in [RFC6775], with an
addition that BT-LE master and BT-LE slave can both be either 6LN or
6LBR.
2. BLUETOOTH Low Energy
BT-LE is designed for transferring small amounts of data infrequently
at modest data rates at a very low cost per bit. BLUETOOTH Special
Interest Group has introduced two trademarks, BLUETOOTH Smart for
single-mode devices (a device that only supports BT-LE) and BLUETOOTH
Smart Ready for dual-mode devices. In the rest of the draft, the
term BT-LE refers to both types of devices.
BT-LE is an integral part of the BT 4.0 specification [BTCorev4.0].
Devices such as mobile phones, notebooks, tablets and other handheld
computing devices which include BT 4.0 chipsets also have the low-
energy functionality of BLUETOOTH. BT-LE is also included in many
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different types of accessories that collaborate with mobile devices
such as phones, tablets and notebook computers. An example of a use
case for a BT-LE accessory is a heart rate monitor that sends data
via the mobile phone to a server on the Internet.
2.1. BLUETOOTH Low Energy stack
The lower layer of the BT-LE stack consists of the Physical (PHY) and
the Link Layer (LL). The Physical Layer transmits and receives the
actual packets. The Link Layer is responsible for providing medium
access, connection establishment, error control and flow control.
The upper layer consists of the Logical Link Control and Adaptation
Protocol (L2CAP), Generic Attribute protocol (GATT) and Generic
Access Profile (GAP) as shown in Figure 1. GATT and BT-LE profiles
together enable the creation of applications in a standardized way
without using IP. L2CAP provides multiplexing capability by
multiplexing the data channels from the above layers. L2CAP also
provides fragmentation and reassembly for large data packets.
+----------------------------------------+------------------+
| Applications |
+----------------------------------------+------------------+
| Generic Attribute Profile | Generic Access |
+----------------------------------------+ Profile |
| Attribute Protocol |Security Manager | |
+--------------------+-------------------+------------------+
| Logical Link Control and Adaptation |
+--------------------+-------------------+------------------+
| Host Controller Interface |
+--------------------+-------------------+------------------+
| Link Layer | Direct Test Mode |
+--------------------+-------------------+------------------+
| Physical Layer |
+--------------------+-------------------+------------------+
Figure 1: BT-LE Protocol Stack
2.2. Link layer roles and topology
BT-LE defines two Link Layer roles: the BT-LE master role and the
BT-LE slave role. A device in the master role, which is called
master from now on, can manage multiple simultaneous connections with
a number of devices in the slave role, called slaves from now on. A
slave can only be connected to a single master. Hence, a BT-LE
network (i.e. a BT-LE piconet) follows a star topology shown in the
Figure 2. This specification primarily addresses the situation where
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the slave is a 6LN but not a 6LBR at the IPv6 level.
[BT-LE slave]-----\ /-----[BT-LE slave]
\ /
[BT-LE slave]-----+[BT-LE Master]+-----[BT-LE slave]
/ \
[BT-LE slave]-----/ \-----[BT-LE slave]
Figure 2: BT-LE Star Topology
A master is assumed to be less constrained than a slave. Hence, in
the primary scenario master and slave will act as 6LoWPAN Border
Router (6LBR) and a 6LoWPAN Node (6LN), respectively.
In BT-LE, communication only takes place between a master and a
slave. Hence, in a BT-LE network using IPv6, a radio hop is
equivalent to an IPv6 link and vice versa.
2.3. BT-LE device addressing
Every BT-LE device is identified by a 48-bit device address. The
BLUETOOTH specification describes the device address of a BTLE device
as:"Devices are identified using a device address. Device addresses
may be either a public device address or a random device address."
[BTCorev4.0]. The public device addresses are based on the IEEE 802-
2001 standard [IEEE802-2001]. The random device addresses are
generated as defined in the BLUETOOTH specification. The device
addresses are always unique within a BT-LE piconet, but the random
addresses are not guaranteed to be globally unique.
2.4. BT-LE packets sizes and MTU
Maximum size of the payload in the BT-LE data channel PDU is 27
bytes. Depending on the L2CAP mode in use, the amount of data
available for transporting bytes in the single BT-LE data channel PDU
ranges between 19 and 27 octets. For power efficient communication
between two BT-LE nodes, data and its header should fit in a single
BT-LE data channel PDU. However, IPv6 requires support for an MTU of
1280 bytes. An inherent function of the BT-LE L2CAP layer, called
Fragmentation and Recombination (FAR), can assist in transferring
IPv6 packets that do not fit in a single BT-LE data channel PDU.
The maximum IPv6 datagram size that can be transported by L2CAP
depends on the L2CAP mode. The Basic L2CAP Mode allows a maximum
payload size (i.e. IPv6 datagram size) of 65535 bytes per L2CAP PDU.
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The rest of the L2CAP modes allow a maximum payload size that ranges
between 65527 and 65533 bytes per L2CAP PDU. Appendix A describes
FAR operation and five L2CAP Modes.
3. Specification of IPv6 over BLUETOOTH Low Energy
BT-LE technology sets strict requirements for low power consumption
and thus limits the allowed protocol overhead. 6LoWPAN standards
[RFC4944], [RFC6775], and [RFC6282] provide useful functionality for
reducing overhead which can be applied to BT-LE. This functionality
comprises of link-local IPv6 addresses and stateless IPv6 address
autoconfiguration (see Section 3.2.1), Neighbor Discovery (see
Section 3.2.2) and header compression (see Section 3.2.3).
A significant difference between IEEE 802.15.4 and BT-LE is that the
former supports both star and mesh topology (and requires a routing
protocol), whereas BT-LE does not currently support the formation of
multihop networks at the link layer. In consequence, the mesh header
defined in [RFC4944] for mesh under routing MUST NOT be used in BT-LE
networks. In addition, a BT-LE node MUST NOT play the role of a
6LoWPAN Router (6LR).
3.1. Protocol stack
In order to enable transmission of IPv6 packets over BT-LE, a new
fixed L2CAP Channel Identifier (Channel ID) is to be reserved for
IPv6 traffic by the BT-SIG. Until the Channel ID is reserved,
prototype implementations can be implemented as is described in the
Appendix B.
Figure 3 illustrates IPv6 over BT-LE stack. UDP and TCP are provided
as examples of transport protocols, but the stack can be used by any
other upper layer protocol capable of running atop of IPv6.
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+----------------------------+
| UDP/TCP/other |
+----------------------------+
| IPv6 |
+----------------------------+
| 6LoWPAN adapted to BT-LE |
+----------------------------+
| BT-LE L2CAP |
+----------------------------+
| BT-LE Link Layer |
+----------------------------+
| BT-LE Physical |
+----------------------------+
Figure 3: IPv6 over BT-LE Stack
3.2. Link model
The concept of IPv6 link (layer 3) and the physical link (combination
of PHY and MAC) needs to be clear and the relationship has to be well
understood in order to specify the addressing scheme for transmitting
IPv6 packets over the BT-LE link. RFC 4861 [RFC4861] defines a link
as "a communication facility or medium over which nodes can
communicate at the link layer, i.e., the layer immediately below
IPv6."
In the case of BT-LE, L2CAP is an adaptation layer that supports the
transmission of IPv6 packets. L2CAP also provides multiplexing
capability in addition to FAR functionality. This specification
requires that FAR functionality MUST be provided in the L2CAP layer.
The L2CAP channel characteristics for the transmission of IPv6
packets on top of BT-LE are the following:
MTU: Equal to or greater than 1280 bytes
Flush Timeout: 0xFFFF (Infinite)
QoS: Best Effort
Mode: Basic Mode
Since FAR in BT-LE is a function of the L2CAP layer, fragmentation
functionality as defined in RFC 4944 [RFC4944] MUST NOT be used in
BT-LE networks. This specification also assumes the IPv6 header
compression format specified in RFC 6282 [RFC6282]. It is also
assumed that the IPv6 payload length can be inferred from the L2CAP
header length and the IID value inferred, with help of Neighbor
Cache, from the link-layer address.
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The BT-LE link between two communicating nodes can be considered to
be a point-to-point or point-to-multipoint link. When one of the
communicating nodes is in the role of a master, then the link can be
viewed as a point-to-multipoint link from the master point of view.
However, due to BT-LE star topology, each branch of the star is
considered to be an individual link and thus the slaves cannot
directly hear each other and also cannot talk to each other with
link-local addresses. The master ensures address collisions do not
occur (see Section 3.2.2).
After the slave and master have connected at the BT-LE level, the
link can be considered up and IPv6 address configuration and
transmission can begin.
3.2.1. Stateless address autoconfiguration
A BT-LE 6LN performs stateless address autoconfiguration as per RFC
4862 [RFC4862]. A 64-bit Interface identifier (IID) for a BT-LE
interface MAY be formed by utilizing the 48-bit BLUETOOTH device
address (see Section 2.3) as defined in RFC 2464 "IPv6 over Ethernet"
specification [RFC2464]. Alternatively, a randomly generated IID
(see Section 3.2.2), MAY be used instead. In the case of randomly
generated IID or randomly generated BLUETOOTH device address, the
"Universal/Local" bit MUST be set to 0 [RFC4291]. Only if the
BLUETOOTH device address is known to be a public address the
"Universal/Local" bit can be set to 1.
As defined in RFC 4291 [RFC4291], the IPv6 link-local address for a
BT-LE node is formed by appending the IID, to the prefix FE80::/64,
as depicted in Figure 4.
10 bits 54 bits 64 bits
+----------+-----------------+----------------------+
|1111111010| zeros | Interface Identifier |
+----------+-----------------+----------------------+
Figure 4: IPv6 link-local address in BT-LE
The tool for a 6LBR to obtain an IPv6 prefix for numbering the BT-LE
network is out of scope of this document, but can be, for example,
accomplished via DHCPv6 Prefix Delegation [RFC3633] or by using
Unique Local IPv6 Unicast Addresses (ULA) [RFC4193]. Due to the link
model of the BT-LE (see Section 2.2) the 6LBR MUST set the "on-link"
flag (L) to zero in the Prefix Information Option [RFC4861]. This
will cause 6LNs to always send packets to the 6LBR, including the
case when the destination is another 6LN using the same prefix.
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3.2.2. 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. BT-LE does not support mesh networks
and hence only those aspects that apply to a star topology are
considered.
The following aspects of the Neighbor Discovery optimizations
[RFC6775] are applicable to BT-LE 6LNs:
1. A BT-LE 6LN MUST register its address with the 6LBR by sending a
Neighbor Solicitation (NS) message with the ARO option and process
the Neighbor Advertisement (NA) accordingly. The NS with the ARO
option SHOULD be sent irrespective of whether the IID is derived from
the unique 48 bit BT-LE device address or the IID is a random value
that is generated as per the privacy extensions for stateless address
autoconfiguration [RFC4941]. Although RFC 4941 [RFC4941] permits the
use of deprecated addresses for old connections, in this
specification we mandate that one interface MUST NOT use more than
one IID at any one time.
2. For sending Router Solicitations and processing Router
Advertisements the BT-LE 6LNs MUST, respectively, follow Sections 5.3
and 5.4 of the [RFC6775].
3.2.3. 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 in this document as the basis for IPv6 header compression on
top of BT-LE. All headers MUST be compressed according to RFC 6282
[RFC6282] encoding formats. The BT-LE's star topology structure can
be exploited in order to provide a mechanism for IID compression.
The following text describes the principles of IPv6 address
compression on top of BT-LE.
In a link-local communication, both the IPv6 source and destination
addresses MUST be elided [RFC6282], since the node knows that the
packet is destined for it even if the packet does not have
destination IPv6 address. On the other hand, a node SHALL learn the
IID of the other endpoint of each L2CAP connection it participates
in. By exploiting this information, a node that receives a data
channel PDU containing an IPv6 packet (or a part of it) can infer the
corresponding IPv6 source address. A node MUST maintain a Neighbor
Cache, in which the entries include both the IID of the neighbor and
the Device Address that identifies the neighbor. For the type of
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communication considered in this paragraph, the following settings
MUST be used in the IPv6 compressed header: CID=0, SAC=0, SAM=11,
DAC=0, DAM=11.
When a 6LN transmits an IPv6 packet to a remote destination using
global Unicast IPv6 addresses, if a context is defined for the prefix
of the 6LNs global IPv6 address, the 6LN MUST indicate this context
in the corresponding source fields of the compressed IPv6 header as
per Section 3.1 of RFC 6282 [RFC6282], and MUST elide the IPv6 source
address. For this, the 6LN MUST use the following settings in the
IPv6 compressed header: CID=1, SAC=1, SAM=11. In this case, the 6LBR
can infer the elided IPv6 source address since 1) the 6LBR has
previously assigned the prefix to the 6LNs; and 2) the 6LBR maintains
a Neighbor Cache that relates the Device Address and the IID of the
corresponding slave. If a context is defined for the IPv6
destination address, the 6LN MUST also indicate this context in the
corresponding destination fields of the compressed IPv6 header, and
MUST elide the prefix of the destination IPv6 address. For this, the
6LN MUST set the DAM field of the compressed IPv6 header as DAM=01
(if the context covers a 64-bit prefix) or as DAM=11 (if the context
covers a full, 128-bit address). CID and DAC MUST be set to CID=1
and DAC=1. Note that when a context is defined for the IPv6
destination address, the 6LBR can infer the elided destination prefix
by using the context.
When a 6LBR receives an IPv6 packet sent by a remote node outside the
BT-LE network, and the destination of the packet is a 6LN, if a
context is defined for the prefix of the 6LN's global IPv6 address,
the 6LBR MUST indicate this context in the corresponding destination
fields of the compressed IPv6 header, and MUST elide the IPv6
destination address of the packet before forwarding it to the 6LN.
For this, the 6LBR MUST set the DAM field of the IPv6 compressed
header as DAM=11. CID and DAC MUST be set to CID=1 and DAC=1. If a
context is defined for the prefix of the IPv6 source address, the
6LBR MUST indicate this context in the source fields of the
compressed IPv6 header, and MUST elide that prefix as well. For
this, the 6LBR MUST set the SAM field of the IPv6 compressed header
as SAM=01 (if the context covers a 64-bit prefix) or SAM=11 (if the
context covers a full, 128-bit address). CID and SAC MUST be set to
CID=1 and SAC=1.
3.2.4. Unicast and Multicast address mapping
The BT-LE link layer does not support multicast. Hence traffic is
always unicast between two BT-LE nodes. Even in the case where a
master is attached to multiple slaves, the master cannot do a
multicast to all the connected slaves. If the master needs to send a
multicast packet to all its slaves, it has to replicate the packet
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and unicast it on each link. However, this may not be energy-
efficient and particular care must be taken if the master is battery-
powered. In the opposite direction, a slave can only transmit data
to a single destination (i.e. the master). Hence, when a slave needs
to transmit an IPv6 multicast packet, the slave will unicast the
corresponding BT-LE packet to the master. As described in the
Section 3.2 the master will not forward link-local multicast messages
to other slaves connected to the master.
3.3. Internet connectivity scenarios
In a typical scenario, the BT-LE network is connected to the Internet
as shown in the Figure 5.
A degenerate scenario can be imagined where a slave is acting as 6LBR
and providing Internet connectivity for the master. How the master
could then further provide Internet connectivity to other slaves,
possibly connected to the master, is out of the scope of this
document.
6LN
\ ____________
\ / \
6LN ---- 6LBR --- | Internet |
/ \____________/
/
6LN
<-- BT-LE -->
Figure 5: BT-LE network connected to the Internet
In some scenarios, the BT-LE network may transiently or permanently
be an isolated network as shown in the Figure 6.
6LN 6LN
\ /
\ /
6LN --- 6LBR --- 6LN
/ \
/ \
6LN 6LN
<------ BT-LE ----->
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Figure 6: Isolated BT-LE network
In the isolated network scenario communications between 6LN and 6LBR
can use IPv6 link-local methodology, but for communications between
different slaves, the master has to act as 6LBR, number the network
with ULA prefix [RFC4193], and route packets between slaves.
4. IANA Considerations
There are no IANA considerations related to this document.
5. Security Considerations
The transmission of IPv6 over BT-LE links has similar requirements
and concerns for security as for IEEE 802.15.4. IPv6 over BT-LE
SHOULD be protected by using BT-LE Link Layer security.
BT-LE Link Layer supports encryption and authentication by using the
Counter with CBC-MAC (CCM) mechanism [RFC3610] and a 128-bit AES
block cipher. Upper layer security mechanisms may exploit this
functionality when it is available. (Note: CCM does not consume
bytes from the maximum per-packet L2CAP data size, since the link
layer data unit has a specific field for them when they are used.)
Key management in BT-LE is provided by the Security Manager Protocol
(SMP), as defined in [BTCorev4.0].
6. Additional contributors
Kanji Kerai, Jari Mutikainen, David Canfeng-Chen and Minjun Xi from
Nokia have contributed significantly to this document.
7. Acknowledgements
The BLUETOOTH, BLUETOOTH Smart and BLUETOOTH Smart Ready marks are
registred trademarks owned by BLUETOOTH SIG, Inc.
Samita Chakrabarti, Erik Nordmark, and Marcel De Kogel have provided
valuable feedback for this draft.
8. References
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8.1. Normative References
[BTCorev4.0]
BLUETOOTH Special Interest Group, "BLUETOOTH Specification
Version 4.0", June 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, December 1998.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, September 2007.
[RFC6282] Hui, J. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
September 2011.
[RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,
"Neighbor Discovery Optimization for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)", RFC 6775,
November 2012.
8.2. Informative References
[IEEE802-2001]
Institute of Electrical and Electronics Engineers (IEEE),
"IEEE 802-2001 Standard for Local and Metropolitan Area
Networks: Overview and Architecture", 2002.
[RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with
CBC-MAC (CCM)", RFC 3610, September 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
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[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, September 2007.
Appendix A. BLUETOOTH Low Energy fragmentation and L2CAP Modes
This section provides an overview of Fragmentation and Recombination
(FAR) method and L2CAP modes in BT-LE. FAR is an L2CAP mechanism, in
which an L2CAP entity can take the (large) upper layer PDU, prepend
the L2CAP header (4 bytes in the Basic L2CAP mode) and break the
resulting L2CAP PDU into fragments which can then be directly
encapsulated into Data channel PDUs. There are bits in the Data
channel PDUs which identify whether the payload is a complete L2CAP
PDU or the first of a set of fragments, or one of the rest of the
fragments.
There are five L2CAP modes defined in the BT 4.0 spec. These modes
are: Retransmission Mode (a Go-Back-N mechanism is used), Enhanced
Retransmission Mode (includes selective NAK among others), Flow
Control Mode (PDUs are numbered, but there are no retransmissions),
Streaming Mode (PDUs are numbered, but there are no ACKs of any kind)
and Basic L2CAP Mode.
Appendix B. BLUETOOTH Low Energy L2CAP Channel ID Usage for 6LoWPAN/
IPv6
The BT-LE Logical Link Control and Adaptation Protocol (L2CAP) uses
Channel Identifiers (IDs) to distinguish the upper layer protocol
carried on top of it. Two devices exchanging IPv6/6LoWPAN packets
need to use a common Channel ID to be able to send and receive the
packets correctly over L2CAP. It is also important that they avoid
using Channel ID's that conflict with other L2CAP usages. For the
initial use of IPv6/6LoWPAN over BT-LE L2CAP, implementers are
recommended to use Channel ID 0x3E from the BLUETOOTH Special
Interest Group reserved space (BLUETOOTH 4.0 Logical Link Control and
Adaptation Protocol Specification -part, table 2.1 [BTCorev4.0]). As
the IPv6/6LoWPAN use becomes more widely adopted, the BT SIG may
allocate 0x3E or some other Channel ID exclusively for IPv6/6LoWPAN.
Any such BT SIG allocation will deprecate the recommendation given in
this Appendix, and a new RFC will be published at the time of
allocation that will update this RFC and specify the allocated value.
The initial implementers are thus recommended to keep their Channel
ID usage capability flexible to potential future changes.
Nieminen, et al. Expires August 16, 2013 [Page 14]
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Authors' Addresses
Johanna Nieminen (editor)
Nokia
Itaemerenkatu 11-13
FI-00180 Helsinki
Finland
Email: johannamaria.nieminen@gmail.com
Teemu Savolainen (editor)
Nokia
Hermiankatu 12 D
FI-33720 Tampere
Finland
Email: teemu.savolainen@nokia.com
Markus Isomaki
Nokia
Keilalahdentie 2-4
FI-02150 Espoo
Finland
Email: markus.isomaki@nokia.com
Basavaraj Patil
6021 Connection drive
Irving, TX 75039
USA
Email: bpatil@ovi.com
Zach Shelby
Sensinode
Hallituskatu 13-17D
FI-90100 Oulu
Finland
Email: zach.shelby@sensinode.com
Nieminen, et al. Expires August 16, 2013 [Page 15]
Internet-Draft IPv6 over BT-LE February 2013
Carles Gomez
Universitat Politecnica de Catalunya/i2CAT
C/Esteve Terradas, 7
Castelldefels 08860
Spain
Email: carlesgo@entel.upc.edu
Nieminen, et al. Expires August 16, 2013 [Page 16]