6lo G. Rizzo, Ed.
Internet-Draft AJ. Jara, Ed.
Intended status: Standards Track A. Olivieri
Expires: September 29, 2015 Y. Bocchi
HES-SO
MR. Palattella
SnT/Univ. of Luxembourg
L. Ladid
SnT/Univ. of Luxembourg/IPv6 Forum
S. Ziegler
C. Crettaz
Mandat International
March 28, 2015
IPv6 mapping to non-IP protocols
draft-rizzo-6lo-6legacy-03
Abstract
IPv6 is an important enabler of the Internet of Things, since it
provides an addressing space large enough to encompass a vast and
ubiquitous set of sensors and devices, allowing them to interconnect
and interact seamlessly. To date, an important fraction of those
devices is based on networking technologies other than IP. An
important problem to solve in order to include them into an
IPv6-based Internet of Things, is to define a mechanism for assigning
an IPv6 address to each of them, in a way which avoids conflicts and
protocol aliasing.
The only existing proposal for such a mapping leaves many problems
unsolved and it is nowadays inadequate to cope with the new scenarios
which the Internet of Things presents. This document defines a
mechanism, 6TONon-IP, for assigning automatically an IPv6 address to
devices which do not support IPv6 or IPv4, in a way which minimizes
the chances of address conflicts, and of frequent configuration
changes due to instability of connection among devices. Such a
mapping mechanism enables stateless autoconfiguration for legacy
technology devices, allowing them to interconnect through the
Internet and to fully integrate into a world wide scale, IPv6-based
IoT.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.1. Example 1 - Building automation systems and IoT . . . 4
2.1.2. Example 2 - KNX and demand-side management . . . . . 5
3. Reference System . . . . . . . . . . . . . . . . . . . . . . 6
4. Issues addressed through the 6TONon-IP mapping mechanism . . 6
5. 6TONon-IP Mapping Method . . . . . . . . . . . . . . . . . . 8
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1. Example 1 - EIB/KNX . . . . . . . . . . . . . . . . . . . 9
6.2. Example 2 - RFID . . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Security considerations . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
10. Normative References . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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1. 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].
2. Introduction
The Future Internet and the IPv6 protocol enable a new generation of
techniques for accessing the network, which extend the Internet
seamlessly to personal devices, sensors, home appliances, enabling
the so called ''Internet of Things'' (IoT). One of the key issues
which presently hampers the development of IoT and limits its
potential is the lack of an efficient common framework for the
integration among the vast and diverse set of protocols and
technologies which compose it. Current sensors and their application
environments employ a large set of technologies which lack efficient
interoperability. Some associations of manufacturers have been
formed to build a common technological framework in specific
application domains, e.g. KNX for building automation
(http://www.knx.org/), ZigBee (ZigBee Alliance)
(http://www.zigbee.org/), and protocols such as X10 and CAN. Such
frameworks are based on very different architectures, and the
protocols which compose them are generally not interoperable.
Finally, most of these technologies were designed in a context of
small and local networks, with limited capabilities, and they were
not conceived for integration within the Internet. One of the ideas
at the basis of the IoT is the constitution of a common set of
protocols which enables the interaction between devices through the
Internet. By enabling interaction through the Internet, new services
could be conceived and implemented, increasing the value produced by
the IoT infrastructure. The adoption of a common framework may make
more economically convenient its deployment, and foster the
development of new smart environments (buildings, cities, etc),
ultimately making possible the full realization of the potential of
the IoT. As deployment of new sensors is typically expensive, it is
unthinkable of putting to disuse an installed set of sensors, once a
new set of devices (typically, IPv6 enabled) is deployed. This is
not an uncommon case, as the set of deployed legacy devices (sensors,
actuators) is to date very large. Rather, mechanisms are needed to
integrate legacy devices into a common IoT platform, in order to
include them in all the present and future services (e.g. devices and
services directory, localization services, etc) which will be
implemented on the IoT. For these reasons, many designers of the
Internet of Things are focusing on building such common access and
communications framework. All the proposals (e.g. CoAP, RESTful Web
services) presently under discussion are based on IPv6. This has
important implications on the addressing of the devices. Indeed a
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common addressing at the device level is mandatory, in order to
implement true Machine to Machine (M2M) communications without Portal
Servers, which would make the whole system difficult to integrate and
scale. The present document focuses on the network layer aspects of
such IPv6 based integration. At the network layer, a mechanism which
assigns an IPv6 address to each device is needed, to solve the
addressing problem. In this document, we propose a new mechanism for
the users and devices to map the different addressing spaces to a
common IPv6 one. Our proposed mechanism solves several issues posed
by some of the mappings adopted so far. Such mapping makes it
possible for every device from each technology to operate through a
common framework based on IPv6 and protocols over IPv6 such as
RESTFul WebServices and Constrained Application Protocol (CoAP). For
each technology, the proposed mechanism maps technology-specific
features to a set of fields defined within the IPv6 address. This
allows the location and identification of the devices in a multi-
protocol card, or in any gateway or Portal Server.
2.1. Examples
In this subsection, we present two examples which help understanding
the importance of adopting a common IPv6 based framework for
interaction between things, and the need for legacy devices to be
individually addressable through IPv6.
2.1.1. Example 1 - Building automation systems and IoT
The IoT is composed by a very large set of devices, which is poised
to grow exponentially in the near future. For this reason, a
directory service is needed, which offers the possibility to
individuate a specific device or set of devices, with given
capabilities or within a given geographical region. Let us assume
such directory lists devices with their IPv6 addresses, and their
function (say a temperature sensor, or a mobile phone, etc). For
instance, let us consider the case of someone willing to build a map
of temperatures in a given geographical region. Such directory
service would allow retrieving the list of available devices within
that region, each with its own IPv6 address. Assume some of those
devices are legacy, non IP based temperature sensors and part of a
given building automation system. Assume also that such system
manages several of those temperature sensors. Even if such system
would be reachable via IP, without having those sensors individually
listed in the directory and appearing as ''autonomous'' things, which
can be polled directly, one should resort to techniques for
retrieving the temperature reading of those sensors which are
specific of that building automation technology. This would make
more complex the implementation of such a temperature map.
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Instead, by having the building automation system expose each sensor
as an IPv6 enabled device, the whole set of temperature sensors would
be accessible in a homogeneous way, greatly simplifying the task.
2.1.2. Example 2 - KNX and demand-side management
KNX is a standardized (EN 50090, ISO/IEC 14543), OSI-based network
communications protocol for intelligent buildings. Among the devices
typically managed through KNX, we find:
o Lighting control systems;
o Heating/ventilation and air conditioning devices;
o Shutter/blind and shading control systems; and
o Energy management and electricity/gas/water metering devices.
KNX devices do not support IP. Therefore, in order to connect a KNX
home network to the Internet, a gateway (KNXnet/IP router) is
necessary. Other technologies for home automation are available
nowadays, in which each smart device (air conditioners, washing
machines, etc) supports IPv6. Let us consider a scenario in which an
utility company offers an agreement to a fraction of its clients. In
exchange for a cut on the energy bill, the utility company gains
direct control over some appliances at the premises of the client.
In this way, by powering off some of those devices in periods when
the production cost of power are very high, the utility company
realizes potentially high savings.
In order to implement this, the utility company sends commands to a
set of devices under its direct control. For recently installed
devices, the utility can assume that they support IPv6, and some
application layer protocols such as CoAP. Therefore a command to
switch off a device would use the IPv6 address to identify the
device, and the application layer protocol to send the actual
command. But for KNX devices, the command should have another
format: the IPv6 address should be the one of the router bridging the
IPv6 and the KNX networks, and upper layers protocols should take
care of identifying the specific device inside the KNX home network
to whom the command should be sent. Having to format a specific
query for each specific home automation protocol adds a level of
complexity which translates into higher costs of implementation and
maintenance of such a service.
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3. Reference System
In this section we describe a reference system where the IPv6 mapping
is used. Such a system includes:
1. A set of networks running non-IPv6-compatible technologies, each
with one or more hosts connected. Such networks generally use
different OSI layer 3 protocols, or they may adopt a technology
which does not have any layer 3 protocol.
2. A proxy, which hosts the IPv6 mapping functionality. Such device
is typically connected to each of the legacy protocols networks,
and it accesses the Internet via the IPv6 protocol. Such IPv6
addressing proxy performs all the necessary conversions and
adaptations between IPv6 and the (local) networking protocol of
the legacy technologies, in a way which depends on the specific
legacy technology considered. This proxy makes use of the IPv6
mapping mechanism in order to transforms the native addressing to
IPv6 Host ID and vice versa in a way that depends on the legacy
technology.
Though in what follows we will describe the proposed mapping with
reference to such a system, the main ideas behind it are more
general, and they apply to settings others than the one of reference
presented here.
4. Issues addressed through the 6TONon-IP mapping mechanism
In this section we highlight the main open issues regarding
assignment of IPv6 addresses to devices which do not support IPv6 or
IPv4, and we describe a set of desirable properties for a mechanism
for automatic assignment of IPv6 addresses to such devices, which we
name henceforth 6TONon-IP. In Appendix A of RFC 4291, a method is
described for creating modified EUI-64 format Interface Identifiers
out of links or nodes with IEEE EUI-64 Identifiers, or with IEEE 802
48-bit MACs. Moreover, for technologies having other link layer
interface identifier, some possible mapping methods are sketched,
leaving for each legacy protocol the possibility to define its own
mapping method.
In the present document, we propose a mapping mechanism which enables
stateless address autoconfiguration for legacy technologies, and
which exploits some protocol specific identifier such as link layer
interface identifiers, and the like. The proposed mapping mechanism
addresses the following issues:
1. Protocol identification: For the legacy protocols to which the
mapping described in RFC 4291 does not apply, a mechanism is
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needed to map an IPv6 address to the right legacy protocol. This
feature is necessary in case of devices which operate as proxy
for more than one legacy technology at the same time.
2. Inter protocol aliasing: Without a mechanism for identifying the
legacy protocol from the host part of the IPv6 address, address
conflicts are possible among devices belonging to different
legacy protocols. For instance, this may happen when the link
layer interface identifier is the same for two devices belonging
to different technologies. As several legacy technologies are
characterized by a small addressing space, address conflicts are
not so unlikely.
3. Conflicts between IPv6 mapped legacy technology addresses and
addresses derived from (modified or not) EUI-64 format interface
identifiers.
4. Intra-protocol aliasing: As several legacy technologies are
characterized by a small addressing space, it is not unlikely to
have two legacy devices, mapped to IPv6 addresses with the same
network ID (for instance, in the case in which they belong to two
separate networks of the same technology, both connected to a
same proxy), and with a same interface identifier, and mapping
therefore to a same IPv6 address.
Moreover, the following is a list of desirable properties for a
6TONon-IP mapping:
1. Consistency: A host should get the same IPv6 address every time
it connects to a same legacy network, assuming that the
configuration of all the other devices in that network remains
unchanged. This allows avoiding to advertise a new address every
time the host reconnects. This feature might be particularly
important for devices which are not always "on", or which are not
permanently connected.
2. Local Uniqueness: For devices which have an IPv6 address with a
same network part, the host part should be unique for each host.
This property allows avoiding address conflicts.
3. Uniqueness within the whole Internet: Coherently with the IoT
vision, the host part of an IPv6 address associated to a host
should be unique within the whole Internet.
Depending on the specific legacy protocol, there might be protocol
specific limitations to the satisfaction of these properties. In
particular, for those protocols which do not have an interface
identifier which is unique, properties 1) and 2) cannot be fully
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satisfied. Indeed, no mapping can solve address conflicts which take
place inside a legacy protocol network. When legacy protocols have a
interface identifier which is unique, this can be used to produce a
unique host part of an IPv6 address, and its uniqueness would
guarantee the satisfaction of properties 1), 2) and 3).
5. 6TONon-IP Mapping Method
In this section we describe the proposed strategy for forming IPv6
addresses from legacy protocol information, and the address format
that derives from it. We assume that (one or more) 64 bits Network
ID prefixes are given to the mapping function, which therefore
computes the 64 bits of the Host ID part of the address (IPv6
interface identifier), in order to form a full IPv6 address.
The input of the proposed mapping function consists in the interface
identifier of the legacy protocol.
In the proposed mapping method, the resulting Host ID part (IPv6
interface identifier) is composed by six fields, as shown in
Figure 1:
o A Technology ID field (11 bits), containing a code which
identifies the specific legacy protocol. This field is split into
two parts, one of 6 bits, and another of 5 bits.
o U/L bit (1 bit), in order to keep compatibility with the mapping
EUI-64 [RFC4291]. The U/L bit is the seventh bit of the first
byte and is used to determine whether the address is universally
or locally administered. This bit is set to "0", in order to
indicate local scope, analogously to what proposed in [RFC4291].
This choice prevents address conflicts with IPv6 interface
identifier generated from IEEE EUI-64 identifiers or IEEE 48-bit
MAC identifiers.
o A Reserved field (4 bits). This field can be used in the future
for the identification of different interfaces for a same
technology (in the same subnetwork).
o Technology Mapping field (32 bits), which maps the interface
identifier of the legacy protocol. For those protocols for which
the IID is not larger than 32 bits, this field contains the 32
bits of the IID. For IID which are larger than 32 bits, a hashing
function is used instead of direct mapping. In particular, some
hashing algorithms such as CRC-32 are suggested. Hashing
satisfies the requirements of consistency and uniqueness within a
subnet with a very high probability, which depends on the hashing
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algorithm used. This field is split into two parts, one of 8
bits, and another of 24 bits.
o The fourth and fifth bytes are both set to to "0x00", in order not
to conflict with EUI-64 interface identifiers.
The resulting format of the Host ID part of the IPv6 address obtained
from the mapping is indicated in Figure 1.
+--------+-------+-------+---------+--------+----------+---------+
| Tech. | U/L | Tech. | Reserved| Tech. | EUI-64 | Tech. |
| ID | "0" | ID | | Mapping| "0x0000" | Mapping |
| MSB | | LSB | | MSB | | LSBs |
|(6 bits)|(1 bit)|(5 bit)| (4 bits)|(8 bits)| (16 bits)|(24 bits)|
+--------+-------+-------+---------+--------+----------+---------+
Figure 1: general format of the host ID part for legacy protocols
6. Examples
In this section we illustrate the proposed mapping method by applying
it on some examples.
6.1. Example 1 - EIB/KNX
We assume the legacy protocol is EIB/KNX. This device has two kind
of addresses: On the one hand, a logical address for management of
group operations, and on the other hand, an individual address for
identification of the device in the topology.
The mapping will be focused for the individual address. This
includes an Area ID (4 bits), Line ID (8 bits), and Device ID (8
Bits). An example, is the value 0x1/0x01/0x01 for a sensor connected
in the Area ID 0x1, Line ID 0x01, and Device ID 0x01.
We apply a hash (CRC-32) to the sequence 0x10101. The result is
0xDEA258A5.
Let us assume that EIB/Konnex Technology ID is "0". Thereby, the
IPv6 interface identifier is "0000:DE00:00A2:58A5", considering the
documentation network 2001:db8::/32. The final IPv6 address for the
legacy device is "2001:db8::DE00:A2:58A5".
The address is presented in the Figure 2.
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+--------+-------+-------+---------+--------+----------+---------+
| Tech. | U/L | Tech. | Reserved| Mapping| EUI-64 | Mapping |
| ID MSB | "0" | ID LSB| | MSB | "0x0000" | LSBs |
|(6 bits)|(1 bit)|(5 bit)| (4 bits)|(8 bits)| (16 bits)|(24 bits)|
| 0x00 | 0 | 0x00 | 0x00 | 0xDE | 0x0000 | 0xA258A5|
+--------+-------+-------+---------+--------+----------+---------+
Figure 2: EIB/KNX example: the IPv6 interface identifier.
6.2. Example 2 - RFID
We assume the legacy protocol is RFID. Each RFID device is
identified by its Electronic Product Code (EPC), whose length may
vary from 96 to 256 bits. Let us assume to have an RFID device whose
EPC is given by 01.23F3D00.8666A3.000000A05 (12 bytes). Let us
assume that the RFID technology ID is "1".
We apply a hash (CRC-32) to the sequence 0x0123F3D008666A3000000A05.
The result is 0xA93AFFA0.
Thereby, the IPv6 interface identifier is "0004:A900:003A:FFA0",
considering the documentation network 2001:db8::/32. The final IPv6
address for the RFID tag is "2001:db8::400:A900:3A:FFA0".
The address is presented in the Figure 2.
+--------+-------+-------+---------+--------+----------+---------+
| Tech. | U/L | Tech. | Reserved| Mapping| EUI-64 | Mapping |
|ID MSB | "0" | ID | | MSB | "0x0000" | LSBs |
|(6 bits)|(1 bit)|(5 bit)| (4 bits)|(8 bits)| (16 bits)|(24 bits)|
| 0x00 | 0 | 0x04 | 0x00 | 0xA9 | 0x0000 | 0x3AFFA0|
+--------+-------+-------+---------+--------+----------+---------+
Figure 3: RFID example: the IPv6 interface identifier.
7. IANA Considerations
Not yet defined.
8. Security considerations
The proposed mapping mechanism, being based on mapping proprietary
protocol ID, results in such ID being incorporated in the final IPv6
address, exposing this piece of information to the Internet. The
concern has been that a user might not want to expose the details of
the system to outsiders. For such concern, which holds also for MAC
address mapping into EUI64 addresses, please refer to appendix B in
[RFC4942].
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9. Acknowledgements
The authors wish to acknowledge the following for their review and
constructive criticism of this proposal: Robert Cragie. Thanks to
the IoT6 European Project (STREP) of the 7th Framework Program (Grant
288445), and the colleagues who have collaborated in this work. In
particular, Antonio Skarmeta from the University of Murcia, Peter
Kirstein and Socrates Varakliotis from the University Colleague
London, and Sebastien Ziegler from Mandat International.
10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
[SENSORS] Jara, A., Moreno-Sanchez, P., Skarmeta, A., Varakliotis,
S., and P. Kirstein,, "IPv6 Addressing Proxy: Mapping
Native Addressing from Legacy Technologies and Devices to
the Internet of Things (IPv6)", Sensors 13, no. 5,
6687-6712, 2013, 2013.
Authors' Addresses
Gianluca Rizzo, Ed.
HES-SO Valais
Technopole 3
Sierre, Valais 3960
Switzerland
Phone: +41-76-6151758
Email: gianluca.rizzo@hevs.ch
Antonio J. Jara, Ed.
HES-SO Valais
Technopole 3
Sierre, Valais 3960
Switzerland
Email: jara@ieee.org
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Alex C. Olivieri
HES-SO Valais
Technopole 3
Sierre, Valais 3960
Switzerland
Email: Alex.Olivieri@hevs.ch
Yann Bocchi
HES-SO Valais
Technopole 3
Sierre, Valais 3960
Switzerland
Email: yann.bocchi@hevs.ch
Maria Rita Palattella
University of Luxembourg
4, rue Alphonse Weicker
Interdisciplinary Centre for Security, Reliability and Trust
Luxembourg
Phone: (+352) 46 66 44 5841
Email: maria-rita.palattella@uni.lu
Latif Ladid
University of Luxembourg / IPv6 Forum
4, rue Alphonse Weicker
Interdisciplinary Centre for Security, Reliability and Trust
Luxembourg
Phone: (+352) 46 66 44 5720
Email: latif@ladid.lu
Sebastien Ziegler
Mandat International
3 rue Champ Baron
1209 Geneva
Switzerland
Email: sziegler@mandint.org
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Cedric Crettaz
Mandat International
3 rue Champ Baron
1209 Geneva
Switzerland
Email: iot6@mandint.org
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