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Technical Report
Access, Terminals, Transmission and Multiplexing (ATTM);
Reverse Power Feed for Remote Nodes
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2 ETSI TR 102 629 V1.1.1 (2009-11)
Reference
DTR/ATTM-06009
Keywords
ADSL, VDSL
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3 ETSI TR 102 629 V1.1.1 (2009-11)
Contents
Intellectual Property Rights . 4
Foreword . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 6
3 Abbreviations . 6
4 Reverse Power Feed for Remote Nodes . 7
4.1 Reverse Power Feed Background . 7
4.2 Power Backup Situations . 8
4.2.1 Case 1 Battery Backup at the NTE . 8
4.2.2 Case 2 Battery Backup at the DP and NTE . 8
4.2.3 Case 3 Battery Backup at the DP Only . 8
4.2.4 Case 4 Battery Backup at the DP and Cabinet . 9
4.2.5 Case 5 Battery Backup at the DP and Cabinet with Forwards Powering from the CO. 9
4.3 Options for Reverse Power and Forwards Power Feed . 10
4.3.1 Reverse Power Feed to the DP. 10
4.4 Reverse Power Feed Architecture . 11
4.4 Reverse Power Feed Options. 11
4.5 U Electrical Interface . 12
R2P
4.5.1 Current standards in force . 12
4.5.2 Telecommunications cables . 12
4.5.3 Safety of personnel . 12
4.6 ONU Power Consumption . 12
4.7 Reverse Power Feed Specification . 13
4.7.1 Distribution Point Reverse Powering . 13
4.7.2 Cabinet Reverse Powering . 14
4.8 Reverse Power Feed and Pots. 15
4.9 Reverse Power Feed States . 16
4.10 Concatenated Reverse Power Feed Architectures . 16
4.11 Power Sharing/Billing Model . 16
4.12 External Requirements on the Reverse Power Feed . 16
History . 17
ETSI
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4 ETSI TR 102 629 V1.1.1 (2009-11)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Access, Terminals, Transmission and
Multiplexing (ATTM).
Introduction
As various European operators consider the deployment of fibre-fed remote nodes that contain ADSL2+/VDSL2
DSLAM equipment, it is necessary to consider the means of powering such remotely located equipment. One such
method, known as "reverse power feed", transmits the power from the customer premises to the fibre-fed remote node
using the distribution-side copper network. ETSI TM6 has agreed to create a new document that defines a reverse
power feed transmission standard and which allows European operators to source suitably compliant equipment for
inclusion in their networks.
ETSI
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5 ETSI TR 102 629 V1.1.1 (2009-11)
1 Scope
The present document identifies the scope of a reverse power feed standard or standards that will allow operators to be
able to source suitably compliant equipment for inclusion in their networks.
The present document will identify the requirements for reverse power feed, consider the coexistence of reverse power
feed with POTS and scenarios involving the deployment of reverse power feed for cabinet and distribution point
locations.
Other issues for consideration include:
- Safety.
- Efficiency.
- Power Back-up.
- Performance monitoring (for further study).
- Reliability (for further study).
- Power-sharing (for further study).
- Billing (for further study).
Other issues such as local laws, unbundling rules and cost are considered out of scope.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
For a specific reference, subsequent revisions do not apply.
Non-specific reference may be made only to a complete document or a part thereof and only in the following cases:
if it is accepted that it will be possible to use all future changes of the referenced document for the purposes of
the referring document;
for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
ETSI
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6 ETSI TR 102 629 V1.1.1 (2009-11)
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] IEEE 802.3: "LAN/MAN CSMA/CD (Ethernet) Access Method".
NOTE: Available at http://standards.ieee.org/getieee802/802.3.html.
[i.2] IR Cooper, DW Faulkner: "Reverse Powering Over DSL".
[i.3] ON Semiconductor AND8333/D: "High Power PoE Applications, On Semiconductor application
sheet", April 2008.
[i.4] ETSI TR 102 614: "Environmental Engineering (EE); Reverse powering of small access network
node by end-user equipment : A4 interface".
[i.5] ETSI EN 300 132-2: "Environmental Engineering (EE); Power supply interface at the input to
telecommunications equipment; Part 2: Operated by direct current (dc)".
[i.6] ETSI ES 202 971: "Access and Terminals (AT); Public Switched Telephone Network (PSTN);
Harmonized specification of physical and electrical characteristics of a 2-wire analogue interface
for short line interface".
[i.7] ETSI TS 102 533: "Environmental Engineering (EE) Measurement Methods and limits for Energy
Consumption in Broadband Telecommunication Networks Equipment".
[i.8] Code Of Conduct on Energy Consumption of Broadband Communication Equipment European
Commission Directorate-General, Joint Research Centre; Final v2: 17 July 2007.
[i.9] CENELEC EN 60950-1: "Information Technology Equipment - Safety Part 1 General
requirements (IEC 60950-1 2005 Modified)".
[i.10] CENELEC EN 60950-21: "Information Technology Equipment - Safety. Part 21 Remote Power
Feeding (IEC 60950-21:2002)".
[i.11] BT contribution 08CC-020, "Remote Node Powering", ITU SG-15, Campbell, CA,
15-19 Sept. 2008.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
3 Abbreviations
For the purposes of the present document, the following terms and definitions apply:
CO Central Office
CPE Customer Premises Equipment
DP Distribution Point
NTE Network Termination Equipment
ONU Optical Network Unit
PD Powered Device
PoE Power over Ethernet
POTS Plain Old Telephony Service
POTSA POTS - Analogue presentation
POTSD POTS - derived
PSE Power Sourcing Equipment
RFT Remote Feeding Telecommunication
RGW Residential GateWay
SELV Safety or Separation Extra Low Voltage
SG Service Gateway
ETSI
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7 ETSI TR 102 629 V1.1.1 (2009-11)
TNV Telecommunication Network Voltage
4 Reverse Power Feed for Remote Nodes
4.1 Reverse Power Feed Background
The basic architecture of a reverse power feed system is shown below in figure 1.
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
POTS
D
SG
Derived Voice
Central Office Fibre-fed Remote Node Local Power Feed
(cabinet or DP located)
Home network
Figure 1: Generic Reverse Power Feed Architecture
Figure 1 shows power being injected at the NTE from a local power source (located within the home/building) which
traverses the local loop to power a fibre-fed remote node which can be located at either the DP or cabinet using the
same copper pair cable that is used to transmit the xDSL to/from the home/fibre-fed remote node. A metallic POTS
service is shown both with an analogue presentation (POTSA) at the NTE and also as a derived POTS service
(POTSD). Voice services can also be implemented as a derived service from the service gateway (SG).
An issue with regards to reverse powered fibre-fed nodes is that of whom/what is responsible for the powering of
common circuitry contained within the node. It is easy to envisage that an individual user could be responsible for the
powering of the remote line terminating/driver electronics corresponding to their particular circuit (see note). However,
it is not so easy to determine who/what is responsible for powering of say the ONU that terminates the fibre link.
NOTE: In practice even this may not be easy to implement since DSL chipsets may be of an octal channel design
and therefore all eight channels will be required to be powered in order to operate a single channel.
There may be occasions where only a single user is providing power to the remote node but this may not be sufficient to
power all of the remote node electronics for proper operation. Also, there may be occasions where say a GPON feed
requests a response from the ONU (for ranging or management purposes) when no users are currently connected and
providing electrical power.
Such situations result in the requirement for battery back-up devices and these may be located in the SG, remote node
itself or the cabinet providing that spare copper-pairs remain connected to the fibre-fed remote node. Figure 2 shows
battery backup devices have been located in the NTE and fibre-fed remote node. It is envisaged that in order to provide
high-reliability services (including lifeline POTS support) then a combination of battery back-up devices will be
distributed throughout the network.
ETSI
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8 ETSI TR 102 629 V1.1.1 (2009-11)
4.2 Power Backup Situations
4.2.1 Case 1 Battery Backup at the NTE
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Fibre-fed Remote Node
(cabinet or DP located)
Figure 2: Battery Backup at NTE
Figure 2 shows the case where battery backup is placed at the NTE. The aim being that if there is a local power failure
then lifeline POTSA (or maybe POTSD) plus OAM support at the remote node can be provided by the battery backup.
4.2.2 Case 2 Battery Backup at the DP and NTE
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Fibre-fed Remote Node
(cabinet or DP located)
Figure 3: Battery Backup at the DP and NTE
Figure 3 shows the addition of another battery backup located at the DP. This gives the advantage in that equipment
located at the DP can remain powered even though no subscribers are connected and thus retaining OAM support.
4.2.3 Case 3 Battery Backup at the DP Only
Figure 4 shows the battery backup being located only at the DP. This arrangement takes away the responsibility for
backup from the subscriber - but probably means in practice that a larger capacity backup device is required
...