IEC TS 62056-8-20:2016

IEC TS 62056-8-20 ®
Edition 1.0 2016-11
TECHNICAL
SPECIFICATION
colour
inside
Electricity metering data exchange – The DLMS/COSEM suite –
Part 8-20: Mesh communication profile for neighbourhood networks

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IEC TS 62056-8-20 ®
Edition 1.0 2016-11
TECHNICAL
SPECIFICATION
colour
inside
Electricity metering data exchange – The DLMS/COSEM suite –

Part 8-20: Mesh communication profile for neighbourhood networks

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220; 35.110; 91.140.50 ISBN 978-2-8322-3682-6

– 2 – IEC TS 62056-8-20:2016 © IEC 2016
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 9
4 Targeted communication environments – Overview . 10
5 Use of the communication layers for this profile . 12
5.1 Information related to the use of the specification specifying the lower layers . 12
5.2 The structure of the profile supporting network meshed communications . 12
5.3 Lower protocol layers and their use. 13
5.3.1 Overview . 13
5.3.2 Physical layer . 13
5.3.3 MAC layer. 13
5.3.4 Service mapping and adaptation layers . 13
5.3.5 Network layer . 14
5.3.6 Transport layer . 14
5.4 Service mapping and adaptation layers . 14
5.4.1 Service mapping . 14
5.4.2 Protocol_Connection_Parameters of the COSEM-OPEN service . 14
5.5 Registration and connection management . 14
5.5.1 Overview . 14
5.5.2 Connectivity management . 14
5.5.3 Registration . 15
6 Identification and addressing scheme . 17
6.1 Overview. 17
6.2 Network addressing . 18
6.2.1 General . 18
6.2.2 Node migration . 19
6.3 Transport addressing . 19
6.3.1 Overview . 19
6.3.2 UDP port . 19
6.3.3 Default UDP ports . 19
6.4 Wrapper addressing . 19
7 Specific considerations for the application layer services . 20
7.1 Overview. 20
7.2 Application association establishment and release: ACSE services . 20
7.2.1 Application associations . 20
7.2.2 Application association life time . 20
7.2.3 COSEM-OPEN and COSEM-RELEASE service parameters . 20
7.3 xDLMS services . 21
7.4 Security mechanisms . 21
7.4.1 General . 21
7.4.2 Broadcast . 21

7.4.3 Lower layers security . 21
7.5 Transferring long application messages . 22
7.6 Media access, bandwidth and timing considerations . 22
7.7 Other considerations . 22
8 Communication configuration and management . 22
8.1 Overview. 22
8.2 Group management . 22
8.3 Delayed and randomized response . 22
9 The COSEM application process . 23
10 Additional considerations for the use of this profile . 23
Annex A (informative) Address management process example . 24
A.1 Registration management . 24
A.2 IP address publication . 24
A.2.1 General . 24
A.2.2 Address lookup . 25

Figure 1 – Mesh neighbourhood network within an AMI environment. 10
Figure 2 – Entities and interfaces of a smart metering system . 12
Figure 3 – The DLMS/COSEM mesh communication profile . 13
Figure 4 – Identification and addressing scheme . 18
Figure A.1 – Registration management process . 25

Table 1 – Send_destination_and_method attribute . 16
Table 2 – Address registration data . 16
Table 3 – Address update data . 16
Table 4 – Client and server SAPs . 19

– 4 – IEC TS 62056-8-20:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICITY METERING DATA EXCHANGE –
THE DLMS/COSEM SUITE –
Part 8-20: Mesh communication profile
for neighbourhood networks
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed that compliance
with this Technical Specification may involve the use of a maintenance service concerning the stack of protocols on
which the present specification IEC 62056-8-20 is based.
The IEC takes no position concerning the evidence, validity and scope of this maintenance service.
The provider of the maintenance service has assured the IEC that he is willing to provide services under
reasonable and non-discriminatory terms and conditions for applicants throughout the world. In this respect, the
statement of the provider of the maintenance service is registered with the IEC. Information may be obtained from:
DLMS User Association
Zug/Switzerland
www.dlms.com
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62056-8-20, which is a technical specification, has been prepared by technical
committee 13: Electrical energy measurement and control.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
13/1673/DTS 13/1704/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62056 series, published under the general title Electricity metering
data exchange – The DLMS/COSEM suite, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
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– 6 – IEC TS 62056-8-20:2016 © IEC 2016
INTRODUCTION
As defined in IEC 62056-1-0, the IEC 62056 DLMS/COSEM suite provides specific
communication profile standards for communication media relevant for smart metering.
Such communication profile standards specify how the COSEM data model and the
DLMS/COSEM application layer can be used on the lower communication media-specific
protocol layers.
Communication profile standards refer to communication standards that are part of the
IEC 62056 DLMS/COSEM suite or to any other open communication standard.
This Technical Specification specifies a DLMS/COSEM IPv6 based communication profile that
can be used in large scale AMI deployments where the Neighbourhood Networks are mesh
networks.
The communication profile specified in this Technical Specification can be used over various
suitable technologies providing a Neighbourhood Network with mesh topology, as long as they
are capable to carry IPv6 traffic.
This specification follows the rules defined in IEC 62056-5-3:2016, Annex A.
The communication profile specified in this specification addresses the specificities resulting
from the properties of the mesh network and the large quantity of devices to be managed.

ELECTRICITY METERING DATA EXCHANGE –
THE DLMS/COSEM SUITE –
Part 8-20: Mesh communication profile
for neighbourhood networks
1 Scope
This part of IEC 62056 specifies a DLMS/COSEM communication profile that can be used in a
smart metering system in which the Neighbourhood Networks (NN) are mesh networks.
This profile may be considered as an adaptation and extension of the UDP/IP communication
profile specified in IEC 62056-9-7:2013. As in that standard, the PHY and MAC layers are out
of the Scope.
This Technical Specification specifies a number of features essential to the efficient operation
of a large scale AMI using mesh NNs. These features include:
• identification of the DLMS/COSEM client and server participating in an application
association (AA) with their system title, so that this identification does not change when
the IP address of the server changes, see Clause 6;
• a mechanism to inform the client of the binding between the server’s system title and its
current IP address(es), see 5.5.3;
• the use of the DLMS/COSEM UDP based transport layer, that allows keeping
DLMS/COSEM AAs open for long periods, while the device may leave and join the mesh
NN and/or its IP address may change, see 7.2.2;
• DLMS/COSEM application layer and application process level security features that can
be used in a mesh environment, see 7.4.2;
• a mechanism to organize servers to one or more groups based on various conditions, so
that the requests can be broadcasted to all devices attached to the mesh network, but only
those servers belonging to the group carry out the request and respond, see 8.2;
• a mechanism that allows to send the response to a request in designated time windows
and with a randomized delay, see 8.3.
• the use of a specific UDP port that allows efficient UDP header compression, see 6.3.3.
The Scope of this communication profile specification is restricted to aspects concerning the
use of communication protocols in conjunction with the COSEM data model and the
DLMS/COSEM application layer. Any project specific definitions of data structures and data
contents may be provided in project specific companion specifications.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary (IEV) (available at
www.electropedia.org)
IEC TR 62051, Electricity metering – Glossary of terms

– 8 – IEC TS 62056-8-20:2016 © IEC 2016
IEC TR 62051-1, Electricity metering – Data exchange for meter reading, tariff and load
control – Glossary of terms – Part 1: Terms related to data exchange with metering
equipment using DLMS/COSEM
IEC 62056-1-0, Electricity metering data exchange – The DLMS/COSEM suite – Part 1-0:
Smart metering standardisation framework
IEC 62056-4-7, Electricity metering data exchange – The DLMS/COSEM suite – Part 4-7:
DLMS/COSEM transport layer for IP networks
IEC 62056-5-3:2016, Electricity metering data exchange – The DLMS/COSEM suite –
Part 5-3: DLMS/COSEM application layer
IEC 62056-6-1, Electricity metering data exchange – The DLMS/COSEM suite – Part 6-1:
Object Identification System (OBIS)
IEC 62056-6-2, Electricity metering data exchange – The DLMS/COSEM suite – Part 6-2:
COSEM interface classes
IEC 62056-9-7:2013, Electricity metering data exchange – The DLMS/COSEM suite –
Part 9-7: Communication profile for TCP-UDP/IP networks
RFC 768, User Datagram Protocol Edited by J. Postel. August 1980. Available from
https://www.ietf.org/rfc/rfc768.txt
RFC 2460, Internet Protocol, Version 6 (Ipv6) Specification [online]. Edited by R. Hinden, S.
Deering. December 1998. Available from http://tools.ietf.org/html/rfc2460
RFC 3315, Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Edited by R. Droms, J.
Bound, B. Volz, T. Lemon, C. Perkins, M. Carney. July 2003. Available from
http://www.ietf.org/rfc/rfc3315.txt
RFC 4291, IP Version 6 Addressing Architecture [online]. Edited by R. Hinden, S. Deering.
February 2006. Available from http://tools.ietf.org/html/rfc4291
RFC 4862, IPv6 Stateless Address Autoconfiguration. Edited by S. Thomson, T.Narten, T.
Jinmei September 2007. Available from https://tools.ietf.org/html/rfc4862
RFC 4944, Transmission of IPv6 Packets over IEEE 802.15.4 Networks [online]. Edited by G.
Montenegro, N. Kushalnagar, D. Culler. September 2007. Available from
http://tools.ietf.org/html/rfc4944
RFC 6282, Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks.
Available from http://tools.ietf.org/html/rfc6282
RFC 6550, IPv6 Routing Protocol for Low-Power and Lossy Networks, Edited by T. Winter, P.
Thubert, A. Brandt, J. Hui, R. Kelsey, P. Lewis, K. Pister, R. Struik, JP. Vasseur, R.
Alexander. March 2012. Available from https://tools.ietf.org/html/rfc6550
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the definitions given in IEC 60050, IEC 62051, IEC 62051-
1 as well as the following apply.

NOTE Where there is a difference between the definitions in the glossary and those contained in product
standards produced by TC 13, then the latter take precedence in applications of the relevant standard.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
mesh network
functional unit for the transfer of data between several participants for data processing, via
one or a number of redundant transmission paths, whereby each participant is able to pass on
data that do not concern themselves to one or more neighbours
3.1.2
Head End System
HES
Central Data System exchanging data via the AMI of various meters in its service area
Note 1 to entry: The HES may communicate via WAN directly to the end devices or via NNAPs and LNAPs.
3.2 Abbreviated terms
AA Application Association
ACSE Association Control Service Element
AL Application Layer
AMI Advanced Metering Infrastructure
AP Application Process
ASE Application Service Element
COSEM Companion Specification for Energy Metering
DCS Data Collection System
DHCPv6 Dynamic Host Configuration Protocol for IPv6
DLMS Device Language Message Specification
DNS Domain Name System
IP Internet Protocol
HES Head End System
HLS High Level Security mechanism
IANA Internet Assigned Numbers Authority
LAN Local Area Network
LN Local Network
LNAP Local Network Access Point
MAC Media Access Control sublayer of the Data Link Layer as specified in the OSI
Open Systems Interconnection Model
NN Neighbourhood Network
NNAP Neighbourhood Network Access Point
PHY Physical Layer as specified in the OSI Open Systems Interconnection Model
RF Radio Frequency
RPL Routing Protocol for Low-Power and Lossy Networks
SAP Service Access Point
TCP Transmission Control Protocol

– 10 – IEC TS 62056-8-20:2016 © IEC 2016
UDP User Datagram Protocol
WAN Wide Area Network
xDLMS Extended DLMS
4 Targeted communication environments – Overview
The objectives of defining a DLMS/COSEM communication profile for mesh neighbourhood
networks are the following:
a) centralized management of a large number of end devices by a single central Head End
System (HES) hosting a (set of) DLMS/COSEM client(s);
b) efficient end-to-end communication between DLMS/COSEM clients and different kind of
devices over Neighbourhood Networks using mesh topology;
c) reliability and efficiency of accessing devices via the mesh network;
d) management of adding, removing and relocating devices using existing open standards.
A segment of an AMI network with devices communicating over a mesh network is shown in
Figure 1.
HES
NNAP1 NNAP2 NNAP3 NNAP4
NN1
NN2
End device
NN3
NN4
DLMS/COSEM
LNAP
End device server
End device
DLMS/COSEM DLMS/COSEM
DLMS/COSEM
server server
End device
server LNAP
DLMS/COSEM
DLMS/COSEM
server
server
End device LNAP
DLMS/COSEM DLMS/COSEM
LNAP
server server
DLMS/COSEM
server
End device End device
DLMS/COSEM DLMS/COSEM
End device
server server
DLMS/COSEM
End device
End device
server
DLMS/COSEM End device
End device
server
End device
DLMS/COSEM
End device
server
IEC
Figure 1 – Mesh neighbourhood network within an AMI environment
Figure 1 depicts a centralized meter data collection and management system.
rd
NOTE 1 It may be managed by a Utility or some other 3 party entity but this aspect is out of the Scope of this
document.
There may be many NNs with a single NNAP each. The NNAP provides access for the HES to
the mesh NN. On the one hand, an NNAP has an interface towards the WAN and the NN. On
the other hand, it acts as the coordinator of the NN, managing the discovery and registration
Local network Neighbourhood Mesh network Wide Area Network

of devices on the mesh network. Concerning DLMS/COSEM data exchange, the NNAP
provides only a routing function.
End devices may be:
• various kind of utility meters e.g. electricity, gas, heat, water meters or other devices with
smart metering and control functions;
• DLMS/COSEM servers, or they may implement another application protocol (e.g. M-Bus or
ZigBee® );
• mains powered or battery powered (electricity meters are always mains powered);
• directly connected to the mesh network, or connected via LNAPs;
• IP capable or not.
The functionality of LNAPs depends on the kind of end devices connected to them:
• when the end devices are mains powered and IP capable DLMS/COSEM servers that are
not directly connected to the mesh network, the LNAP is simply a router;
• when the end devices are mains powered not IP capable DLMS/COSEM servers that
therefore cannot be directly connected to the mesh network, the LNAP acts as a
DLMS/COSEM gateway and as a master of the LN;
• when the end devices are battery powered DLMS/COSEM servers that cannot be directly
connected to the mesh network, the LNAP acts as a proxy that exchanges data with the
end devices when they are awake and that can store requests to and responses from the
DLMS/COSEM servers. The LNAP also acts as a master of the LN;
• when the end devices are not DLMS/COSEM servers, then the LNAP acts as a master for
tho
...