ETSI ETS 300 300 ed.1 (1995-02)

SLOVENSKI STANDARD
01-december-2003
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Broadband Integrated Services Digital Network (B-ISDN); Synchronous Digital Hierarchy
(SDH) based user network access; Physical layer interfaces for B-ISDN applications
Ta slovenski standard je istoveten z: ETS 300 300 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 300
TELECOMMUNICATION February 1995
STANDARD
Source: ETSI TC-NA Reference: DE/NA-052512
ICS: 33.080
Access, broadband, interface, ISDN
Key words:
Broadband Integrated Services Digital Network (B-ISDN);
Synchronous Digital Hierarchy (SDH) based user network access
Physical layer interfaces for B-ISDN applications
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1995. All rights reserved.
New presentation - see History box

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ETS 300 300: February 1995
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 300: February 1995
Contents
Foreword .7
1 Scope .9
2 Normative references.9
3 Definitions and abbreviations .10
3.1 Definitions .10
3.2 Abbreviations .10
4 Reference configuration at the user-network interface .11
4.1 Functional groups and reference points .11
4.2 Examples of physical realizations.11
4.3 Basic characteristics of the interfaces at T and S reference points.15
B B
4.3.1 Characteristics of the interfaces at 155 520 kbit/s .15
4.3.1.1 Interface at T reference point.15
B
4.3.1.2 Interface at the S reference point.15
B
4.3.1.3 Relationship between interfaces at S and T .15
B B
4.3.2 Characteristics of the interfaces at 622 080 kbit/s .15
4.3.2.1 Interface at T reference point.15
B
4.4 Relationship between ISDN interfaces .15
4.5 Functional groups characteristics .15
4.5.1 Network termination 1 for B-ISDN (B-NT1).15
4.5.2 Network termination 2 for B-ISDN (B-NT2).16
4.5.3 Terminal equipment for B-ISDN (B-TE) .17
4.5.3.1 Terminal equipment type 1 for B-ISDN (B-TE1).17
4.5.3.2 Terminal equipment type 2 for B-ISDN (B-TE2).17
4.5.4 Terminal adapter for B-ISDN (B-TA).17
5 UNI specifications.17
5.1 Interface location with respect to reference configuration .17
5.2 Interface location with respect to the wiring configuration .18
6 Service and layering aspects of the physical layer.18
6.1 Services provided to the ATM-layer.18
6.2 Service primitives exchanged with the ATM layer .18
6.3 Sublayering of the physical layer .18
7 Physical medium characteristics of the UNI at 155 520 kbit/s .19
7.1 Characteristics of the interface at the T reference point .19
B
7.1.1 Bit rate and interface symmetry.19
7.1.2 Physical characteristics .19
7.1.2.1 Electrical interface .19
7.1.2.1.1 Interface range .19
7.1.2.1.2 Transmission medium .19
7.1.2.1.3 Electrical parameters at interface points I and I .19
a b
7.1.2.1.4 Electrical connectors .19
7.1.2.1.5 Line coding .19
7.1.2.1.6 Electromagnetic compatability and electromagnetic
interference requirements.20
7.1.2.2 Optical interface.21
7.1.2.2.1 Attenuation range .21
7.1.2.2.2 Transmission medium .21
7.1.2.2.3 Optical parameters .21
7.1.2.2.3.1 Line coding .21
7.1.2.2.3.2 Operating wavelength.21
7.1.2.2.3.3 Input and output port characteristics .22

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ETS 300 300: February 1995
7.1.2.2.4 Optical connectors . 22
7.1.2.2.5 Safety requirements. 22
7.2 Characteristics of the interface at the S reference point. 22
B
8 Physical medium characteristics of the UNI at 622 080 kbit/s. 22
8.1 Characteristics of the interface at the T reference point. 22
B
8.1.1 Bit rate and interface symmetry. 22
8.1.2 Physical characteristics . 22
8.1.2.1 Attenuation range. 22
8.1.2.2 Transmission medium. 23
8.1.2.3 Optical parameters. 23
8.1.2.3.1 Line coding. 23
8.1.2.3.2 Operating wavelength . 23
8.1.2.3.3 Input and output port characteristics. 23
8.1.2.4 Optical connectors . 23
8.1.2.5 Safety requirements. 23
8.2 Characteristics of the interface at the S reference point. 23
B
9 Power feeding. 24
9.1 Provision of power. 24
9.2 Power available at B-NT1. 24
9.3 Feeding voltage. 24
9.4 Safety requirements . 24
10 Functions provided by the transmission convergence sublayer . 24
10.1 Transfer capability. 24
10.1.1 Interface at 155 520 kbit/s . 24
10.1.2 Interface at 622 080 kbit/s . 25
10.2 Physical Layer aspects. 25
10.2.1 Timing. 25
10.2.2 Interface structure for 155 520 kbit/s. 25
10.2.3 Interface structure for 622 080 kbit/s. 27
10.3 Header error control . 28
10.3.1 Header error control functions . 28
10.3.2 Header error control sequence generation. 30
10.4 Idle cells . 30
10.5 Cell delineation and scrambling . 31
10.5.1 Cell delineation and scrambling objectives. 31
10.5.1.1 Cell delineation algorithm. 31
10.5.2 Cell delineation performance. 32
10.5.3 Scrambler operation . 32
11 UNI related OAM functions. 32
11.1 Transmission overhead allocation. 32
11.2 Maintenance signals. 33
11.3 Transmission performance monitoring. 34
11.4 Control communication . 34
12 Operational functions. 34
12.1 Definition of signals . 34
12.2 Definitions of state tables at network and user sides. 35
12.2.1 Layer 1 states on the user side of the interface. 35
12.2.2 Layer 1 states at the network side of the interface . 37
12.2.3 Definition of primitives. 39
12.2.4 State tables. 39

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ETS 300 300: February 1995
Annex A (informative): Impact of random bit errors on HEC performance .43
Annex B (informative): Impact of random bit errors on cell delineation performance.44
Annex C (informative): Bibliography.45
History.46

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ETS 300 300: February 1995
Foreword
This European Telecommunication Standard (ETS) has been produced by the Network Aspects (NA)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS defines the Synchronous Digital Hierarchy (SDH) based user network access physical layer
interfaces to be applied to the T , S reference points of the reference configurations of the Broadband
B B
Integrated Services Digital Network (B-ISDN) User Network Interface (UNI) for B-ISDN applications. It
addresses the structure of the transmission system that is used at these interfaces as well as the
implementation of the UNI related Operation And Maintenance (OAM) functions at the SDH-based
physical layer.
The production of this ETS has taken into account the recommendations given in CCITT
Recommendations I.413 [11] and I.432 [12].
Transposition dates
Date of latest announcement of this ETS (doa): 31 May 1995
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 November 1995
Date of withdrawal of any conflicting National Standard (dow): 30 November 1995

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ETS 300 300: February 1995
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ETS 300 300: February 1995
1 Scope
This European Telecommunication Standard (ETS) defines the physical layer interface to be applied to
the S and T reference points of the reference configurations of the Broadband Integrated Services
B B
Digital Network (B-ISDN) Synchronous Digital Hierarchy (SDH) based User Network Interface (UNI) at
155 520 kbit/s and 622 080 kbit/s. It addresses separately the physical media and the transmission
system used at these interfaces and addresses also the implementation of UNI related Operation And
Maintenance (OAM) functions.
The selection of the physical medium for the interfaces at the S and T reference points should take into
B B
account that optical fibre is agreed as the preferred medium to be used to cable customer equipment.
However, in order to accommodate existing cabling of customer equipment, other transmission media
(e.g. coaxial cables) should not be precluded. Also, implementations should allow terminal
interchangeability.
This ETS reflects in its structure and content the desire to take care of such early configurations and
introduces a degree of freedom when choosing a physical medium at the physical layer.
2 Normative references
This ETS incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ITU-T Recommendation G.652: "Characteristics of a single-mode optical fibre
cable".
[2] CCITT Recommendation G.703: "Physical/electrical characteristics of
hierarchical digital interfaces".
[3] ITU-T Recommendation G.707: "Synchronous digital hierarchy bit rates".
[4] ITU-T Recommendation G.708: "Network node interface for the synchronous
digital hierarchy".
[5] ITU-T Recommendation G.709: "Synchronous multiplexing structure".
[6] ITU-T Recommendation G.783: "Characteristics of Synchronous Digital
Hierarchy (SDH) multiplexing equipment functional blocks".
[7] ITU-T Recommendation G.957: "Optical interfaces for equipments and systems
relating to the synchronous digital hierarchy".
[8] CCITT Recommendation I.113 (1992): "Vocabulary of terms for broadband
aspects of ISDN".
[9] CCITT Recommendation I.321 (1992): "B-ISDN protocol reference model and
its application".
[10] CCITT Recommendation I.361 (1992): "B-ISDN ATM layer specification".
[11] CCITT Recommendation I.413 (1992): "B-ISDN user-network interface".
[12] CCITT Recommendation I.432 (1992): "B-ISDN user-network interface -
Physical layer specification".
[13] CCITT Recommendation I.610 (1992): "B-ISDN operation and maintenance
principles and functions".
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ETS 300 300: February 1995
[14] CCITT Recommendation X.200: "Reference model of Open System
Interconnection for CCITT Applications".
[15] I-ETS 300 404: "Broadband Integrated Services Digital Network (B-ISDN);
B-ISDN Operation And Maintenance (OAM) principles and functions".
[16] IEC Publication 825: "Radiation safety of laser products equipment classification
requirements and user's guide".
[17] IEC Publication 950: "Safety of information technology equipment, including
electrical business equipment".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the definitions given in CCITT Recommendation I.113 [8] apply, specially for
idle cell, valid cell and invalid cell.
to be defined: These items or values are not yet specified.
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
AIS Alarm Indication Signal
ATM Asynchronous Transfer Mode
AU Administrative Unit
B-NT Broadband Network Termination
B-TA Broadband Terminal Adapter
B-TE Broadband Terminal Equipment
BER Bit Error Rate
BIP Bit Interleaved Parity
CATV Category V
CLP Cell Loss Priority
CMI Coded Mark Inversion
CRC Cyclic Redundancy Check
EMC Electro-Magnetic Compatibility
EMI Electro-Magnetic Interference
FEBE Far End Block Error
FERF Far End Receive Failure
HEC Header Error Control
LAN Local Area Network
LSB Least Significant Bit
MA Medium Adapter
MPH Management Physical Header
MSB Most Significant Bit
NNI Network Node Interface
ISDN Integrated Services Digital Network
B-ISDN Broadband Integrated Services Digital Network
PH Physical Header
NRZ Non Return to Zero
OAM Operation And Maintenance
OSI Open Systems Interconnection
PM Physical Medium
POH Path Overhead
p.p.m. parts per million
PTR Pointer
SDH Synchronous Digital Hierarchy
SOH Section Overhead
STI Surface Transfer Impedance
STM Synchronous Transport Module
TC Transmission Convergence
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ETS 300 300: February 1995
TFV Terminal Failure Voltage
UNA User Network Access
UNI User Network Interface
VC Virtual Container
4 Reference configuration at the user-network interface
4.1 Functional groups and reference points
The reference configurations defined for ISDN basic access and primary access are considered general
enough to be applicable to all aspects of the B-ISDN accesses.
Figure 1 shows the B-ISDN reference configurations which contain the following:
- functional groups: B-NT1; B-NT2; B-TE1; TE2; B-TE2; and B-TA;
- reference points: T ; S and R.
B B;
S T
B
B
B-TE1 B-NT2 B-NT1
R S
B
TE2
B-TA
or
B-TE2
Reference point
B -TA  B roadband Term inal Adaptor
B -TE  B roadband Term inal Equipm ent
B-NT  Broadband Network Term ination
Functional group
Figure 1: B-ISDN reference configurations
In order to clearly illustrate the broadband aspects, the notation for reference points and for functional
groups with broadband capabilities are appended with the letter B (e.g. B-NT1, T ). The broadband
B
functional groups are equivalent to the functional groups defined in ISDN. Interfaces at the R reference
point may or may not have broadband capabilities.
Interfaces at reference points S and T will be standardized. These interfaces will support all ISDN
B B
services.
4.2 Examples of physical realizations
Figure 2 gives examples of physical configurations illustrating combinations of physical interfaces at
various reference points. The examples cover configurations that could be supported by standardized
interfaces at reference points S and T . Other configurations may also exist. For example, physical
B B
configurations of B-NT2 may be distributed or use shared medium to support Local Area Network (LAN)
emulation and other applications.
Figure 3 illustrates possible physical configurations, but does not preclude alternative configurations.
Whether a single interface at the S reference point can cover different configurations, as illustrated in
B
figure 3, is for further study.

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ETS 300 300: February 1995
Figures 2a) and 2b) show separate interfaces at the S and T reference points; figures 2c) and 2d) show
B B
an interface at S but not at T ; figures 2e) and 2f) show an interface at T but not at S ; figures 2g) and
B B B B
2h) show separate interfaces at S, S and T ; figures 2i) and 2j) show interfaces at S and T which are
B B B B
coincident.
Additionally, figures 2b), 2d), 2f), 2h) and 2j) show an interface at reference point R.
B-TE1
B-NT2 B-NT1
a)
S T
BB
TE2 or
B-TA B-NT2 B-NT1
b)
B-TE2
R S T
BB
Configurations where B-ISDN physical interfaces occur at reference points S and T .
B B
B-TE1
c) B-NT2 B-NT1
+
S
B
TE2 or
B-TA
d) B-NT2 + B-NT1
B-TE2
S
R
B
Configurations where B-ISDN physical interfaces occur at reference point S only.
B
B-TE B-NT2 B-NT1
e)
+
T
B
TE2 or
B-TA B-NT2 B-NT1
+
f)
B-TE2
T
R
B
Configurations where B-ISDN physical interfaces occur at reference point T only.
B
TE1
g)
S
B-NT2 B-NT1
T
B
B-TE1
S
B
TE2
h) TA
S
R
B-NT2
B-NT1
T
B
B-TE1
S
B
Configurations where B-ISDN and ISDN physical interfaces occur at reference points S, S and T .
B B
B-TE1 B-NT1
i)
S  and T
B B
coincident
TE2 or
B-TA B-NT1
j)
B-TE2
R
S  and T
B B
coincident
Configurations where a single B-ISDN physical interface occurs at a location where both reference
points S and T coincide.
B B
Physical interface at the Equipm ent im plem enting
designated reference point functional groups
Figure 2: Examples of physical configurations for broadband user applications

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ETS 300 300: February 1995
a) centralised B-NT2 configuration:
B - TE1
S
B
T
B
S
B
B - TE1
B - N T2 B - NT1
S
B
B - TE1
b) distributed B-NT2 configurations:
b1) generic configuration
B - NT2
(note 5)
T
WW W
B
MA MA MA MA
B - NT1
(note 1)
S S
B B
B - TA
B - TA
R R
TE2 TE2
or or
B - TE1
B - TE2 B - TE2
b2) physical configurations
WW
T
B
MA MA MA
B - NT1
S S
B B
B - TE1 B - TE1
B - TE1
S
B
WW
MA
S T
B B
B - TE1
B - NT1
MA MA
W W
MA
S
B
B - TE1
Figure 3: Examples of physical configurations for multipoint applications (continued)

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ETS 300 300: February 1995
c) multiaccess B-TE configurations:
c1) generic configurations (note 7)
(note 3)
S
T
SS SS
B B
B B
B - NT2
B - NT1
B - TE B - TE B - TE
* * *
c2) physical configurations
SS SS
B B
B - TE B - TE B - TE
S
* * *
B
T
SS SS
S
B
B B B
B - NT2
B - NT1
B - TE B - TE B - TE
* * *
S
B
SS SS
B B
B - TE B - TE B - TE
* * *
(note 4)
(note 5)
SS SS S
T
B B B B
B - N T2 B - NT1
B - TE B - TE B - TE
* * *
(note 4)
(note 5)
(note 6)
S
B
SS SS
S T
B B B B
B - TE B - TE B - TE B - N T2
B - NT1
* * *
NOTE 1: MA: Medium Adapter; accommodates the specific topology of the distributed B-NT2.
The interface at W may include topology dependant elements; it may be a non-
standardized interface.
NOTE 2: There will be a physical link between these two Medium Adapters in the case of ring
configurations.
NOTE 3: There will be a physical link between B-TE* and B-NT2 in the case of ring
configurations.
NOTE 4: B-TE* includes shared medium access functions.
NOTE 5: The measurable physical characteristics of the SS interface are identical to those of
B
the S interface. The functional characteristics of the interface, however, may be a
B
superset of those at the S interface.
B
NOTE 6: The B-NT2 may be null in the case of commonalty between S and T .
B B
NOTE 7: Additional termination functions (e.g. for loopback in bus configuration) and OAM
functions may be necessary for multiaccess B-TE configurations. Requirements and
implementations of these functions are for further study.
Figure 3 (concluded): Examples of physical configurations for multipoint applications

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ETS 300 300: February 1995
4.3 Basic characteristics of the interfaces at T and S reference points
B B
4.3.1 Characteristics of the interfaces at 155 520 kbit/s
4.3.1.1 Interface at T reference point
B
There is only one interface per B-NT1 at the T reference point. The operation of the physical medium is
B
point-to-point in the sense that there is only one sink (receiver) in front of one source (transmitter).
Point-to-multipoint configurations at T at the ATM and higher layers are for further study.
B
4.3.1.2 Interface at the S reference point
B
One or more S interfaces per B-NT2 are present. The interface at the S reference point is point-to-point
B B
at the physical layer in the sense that there is only one sink (receiver) in front of one source (transmitter)
and may be point to multipoint at the other layers.
4.3.1.3 Relationship between interfaces at S and T
B B
Configurations described in figures 2i) and 2j) require that the interface specifications at T and S should
B B
have a high degree of commonalty, in order to ensure that a simple broadband terminal may be
connected directly to the T interface.
B
The feasibility of achieving the needed commonalty is for further study.
4.3.2 Characteristics of the interfaces at 622 080 kbit/s
4.3.2.1 Interface at T reference point
B
There is only one interface per B-NT1 at the T reference point. The operation of the physical medium is
B
point-to-point in the sense that there is only one sink (receiver) in front of one source (transmitter).
Point-to-multipoint configurations at T at the ATM and higher layers are for further study.
B
4.4 Relationship between ISDN interfaces
Figures 2g) and 2h) show configurations where B-ISDN and ISDN interfaces may occur at S and S
B
respectively. In this case B-NT2 functionalities have to ensure the interface capabilities for both S and S .
B
Other configurations for supporting terminals at the interface at the S reference point may exist.
4.5 Functional groups characteristics
Lists of functions for each functional group are given below. Each particular function is not necessarily
restricted to a single functional group. For example, "interface termination" functions are included in the
function lists of B-NT1, B-NT2 and B-TE. The function lists for B-NT1, B-NT2, B-TE and B-TA are not
exhaustive. Not all specific functions in a functional group need to be present in all implementations.
4.5.1 Network termination 1 for B-ISDN (B-NT1)
This functional group includes functions broadly equivalent to layer 1 of the OSI reference model.
Examples of B-NT1 functions are:
- line transmission termination;
- transmission interface handling;
- OAM functions.
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ETS 300 300: February 1995
4.5.2 Network termination 2 for B-ISDN (B-NT2)
This functional group includes functions broadly equivalent to layer 1 and higher layers of the CCITT
Recommendation X.200 [14] reference model. B-NT2 can be null in the case of commonalty between T
B
and S .
B
Examples of B-NT2 functions are:
- adaptation functions for different media and topologies (MA functions);
- functions of a distributed B-NT2;
- cell delineation;
- concentration;
- buffering;
- multiplexing/demultiplexing;
- resource allocation;
- usage parameter control;
- adaptation layer functions for signalling (for internal traffic);
- interface handling (for the T and S interfaces);
B B
- OAM functions;
- signalling protocol handling;
- switching of internal connections.
B-NT2 implementations may be concentrated or distributed. In a specific access arrangement, the B-NT2
may consist only of physical connections. When present, implementations of the B-NT2 are locally
powered.
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ETS 300 300: February 1995
4.5.3 Terminal equipment for B-ISDN (B-TE)
This functional group includes functions broadly belonging to layer 1 and higher layers of the CCITT
Recommendation X.200 [14] reference model.
Examples of B-TE functions are:
- user/user and user/machine dialogue and protocol;
- interface termination and other layer 1 functions;
- protocol handling for signalling;
- connection handling to other equipments;
- OAM functions.
The possibility of powering the B-TE via the S interface is for further study.
B
4.5.3.1 Terminal equipment type 1 for B-ISDN (B-TE1)
This functional group includes functions belonging to the B-TE functional group with an interface that
complies with the B-ISDN S and/or T interface recommendations.
B B
4.5.3.2 Terminal equipment type 2 for B-ISDN (B-TE2)
This functional group includes functions belonging to the functional group B-TE but with a broadband
interface that complies with interface CCITT Recommendations other than the B-ISDN interface CCITT
Recommendations or interfaces not included in CCITT Recommendations.
4.5.4 Terminal adapter for B-ISDN (B-TA)
This functional group includes functions broadly belonging to layer 1 and higher layers of the CCITT
Recommendation X.200 [14] reference model that allow a TE2 or a B-TE2 terminal to be served by a
B-ISDN UNI.
5 UNI specifications
5.1 Interface location with respect to reference configuration
An interface point I is adjacent to the B-TE or the B-NT2 on their network side; interface point I is
a b
adjacent to the B-NT2 and to the B-NT1 on their user sides (see figure 4).
I I I I
ab ab
B-TE B-NT1
B-NT2
S
T
B B
Figure 4: Reference configuration at reference points S and T
B B
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ETS 300 300: February 1995
5.2 Interface location with respect to the wiring configuration
The interface points are located between the socket and the plug of the connector attached to the B-TE,
B-NT2 or B-NT1. The location of the interface point is shown in figure 5.
In this ETS, the term "B-NT" is used to indicate network terminating layer 1 aspects of B-NT1 and B-NT2
functional groups, and the term "TE" is used to indicate terminal terminating layer 1 aspects of B-TE1,
B-TA and B-NT2 functional groups, unless otherwise indicated.
connecting cord
(note)
I
I b
a
B - T E
B - NT
W iring at the
custom er prem ises
NOTE: The length of the connecting cord can be zero.
Figure 5: Wiring configuration
6 Service and layering aspects of the physical layer
6.1 Services provided to the ATM-layer
The physical layer provides for the transparent transmission of ATM-PDUs between physical layer service
access points (Ph-SAP). The ATM-PDU is called ATM cell. The ATM cell is defined in CCITT
Recommendation I.361 [10]. As no addressing is implemented in the physical layer only a single Ph-SAP
can exists at the boundary between physical layer and ATM layer. The interarrival time between cells
passed to the ATM layer is not defined (asynchronous transmission). The physical layer provides the ATM
layer with timing information.
6.2 Service primitives exchanged with the ATM layer
The service primitives between physical layer and ATM-layer are defined in CCITT Recommendation
I.361 [10], § 3.2.
6.3 Sublayering of the physical layer
The physical layer is subdivided into two sublayers:
- the Physical Medium (PM) sublayer;
- the Transmission Convergence (TC) sublayer.
No service access point and service primitives are defined between the PM and the TC sublayers. The
functions of the individual sublayer are defined in CCITT Recommendation I.321 [9].

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7 Physical medium characteristics of the UNI at 155 520 kbit/s
7.1 Characteristics of the interface at the T reference point
B
7.1.1 Bit rate and interface symmetry
The bit rate of the interface is 155 520 kbit/s. The interface is symmetric, i.e. it has the same bit rate in
both transmission directions.
The nominal bit rate in free running clock mode shall be 155 520 kbit/s with a tolerance of ± 20 parts per
million (p.p.m.).
7.1.2 Physical characteristics
Both optical and electrical interfaces are recommended. The implementation selected depends on the
distance to be covered and user requirements arising from the details of the installation.
7.1.2.1 Electrical interface
7.1.2.1.1 Interface range
The maximum range of the interface depends on the specific attenuation of the transmission medium
used. For example a maximum range of about 100 meters for microcoax (4 mm diameter) and 200
meters for CATV type (7 mm diameter) can be achieved.
7.1.2.1.2 Transmission medium
Two coaxial cables, one for each direction, shall be used. The wiring configuration shall be point-to-point.
The impedance shall be 75 Ω with a tolerance of ± 5 % in the frequency range 50 MHz to 200 MHz.
The attenuation of the electrical path between the interface points I and I shall be assumed to follow an
a b
approximate √f law and to have a maximum insertion loss of 20 dB at a frequency of 155 520 kHz.
7.1.2.1.3 Electrical parameters at interface points I and I
a b
The digital signal presented at the output port and the port impedance should conform to table 11 and
figures 24 and 25 of CCITT Recommendation G.703 [2] for the interface at 155,52 Mbit/s.
The digital signal presented at the input port and the port impedance should conform to table 11 and
figures 24 and 25 of CCITT Recommendation G.703 [2] for the interface at 155,52 Mbit/s modified by the
characteristics of the interconnecting coaxial pair.
7.1.2.1.4 Electrical connectors
The presentation of interface point I at B-NT1 or B-NT2 shall be via a socket.
b
The presentation of interface point I at B-TE or B-NT2 shall be using either:
a
a) a socket, i.e. the connection shall be made to the equipment toward the network with a cable with
plugs on both ends; or
b) an integral connecting cord with plug on the free end.
7.1.2.1.5 Line coding
The line coding shall be Coded Mark Inversion (CMI); see CCITT Recommendation G.703 [2] § 2.1.

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ETS 300 300: February 1995
7.1.2.1.6 Electromagnetic compatability and electromagnetic interference requirements
Shielding properties of connectors and cables are defined by the specification of the respective values for
the Surface Transfer Impedance (STI). The template indicating the maximum STI values for Category V
(CATV) cables is given in figure 6. For connectors, these template values shall be multiplied by 10 (i.e.
+20 dB).
The immunity of the interface against induced noise on the transmission medium should be specified by
means of a Terminal Failure Voltage (TFV) which is overlaid to the digital signal at the output port.
Figure 7 shows a possible measurement configuration.
The receiver should tolerate a sinusoidal TFV with the values defined in figure 8 and table 1 without
degradation of the Bit Error Rate (BER) performance.
B
log  S TI
A
fff
log frequency
frequency (MHz):
STI value (Ω/m):
f = 0,1 A = 0,01
f = 100 B = 1
f = 1 000
Figure 6: Maximum STI values as function of frequency for CATV cables
NOTE: The applicability of these values for microcoax cables is for further study.
Transmit Receiver
BER
Transmission
signal under
+
cable
test
generator Analyser
TFV
Generator
Figure 7: Measurement configuration

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ETS 300 300: February 1995
TFV
level
dBV
A
A
F F F
frequency (MHz)
1 2
Figure 8: Terminal Failure Voltage (TFV) frequency response
Table 1: Terminal failure voltage values
frequency (MHz) TFV amplitude (dBV)
(0 dBV = 1V
op)
F =1
F =200
A1≥ -17
F =400
A2≥ -11
7.1.2.2 Optical interface
7.1.2.2.1 Attenuation range
The attenuation of the optical path between the specification points S and R shall be in the range of 0 dB
to 7 dB (see subclause 7.1.2.2.3).
7.1.2.2.2 Transmission medium
The transmission medium shall consist of two single mode fibres, according to ITU-T Recommendation
G.652 [1], one for each direction.
7.1.2.2.3 Optical parameters
7.1.2.2.3.1 Line coding
The line coding shall be binary Non Return to Zero (NRZ).
The convention used for optical logic level is:
- emission of light for a binary ONE;
- no emission of light for a binary ZERO.
The extinction ratio shall be in accordance with ITU-T Recommendation G.957 [7], Application code I-1.
7.1.2.2.3.2 Operating wavelength
The operating wavelength shall be around 1 310 nm (second window).

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ETS 300 300: February 1995
7.1.2.2.3.3 Input and output port characteristics
The optical parameters will be in accordance with ITU-T Recommendation G.957 [7], Application
code I-1.
The specification points associated with interface points I and I correspond to measurement "reference
a b
points" S and R as defined in ITU-T Recommendation G.957 [7]. The optical parameters are specified for
the transmitter and receiver at these specification points and for the optical path between these
specification points, i.e. the connector at the interface is considered to be part of the equipment and not
part of the fibre installation.
7.1.2.2.4 Optical connectors
The presentation of interface point I at B-NT1 or B-NT2 is via a socket.
b
The presentation of interface point I at B-TE or B-NT2 is using either:
a
a) a socket, i.e. the connection is to be made to the equipment toward the network with a cable with
plugs on both ends; or
b) an integral connecting cord with plug on the free end.
7.1.2.2.5 Safety requirements
For safety reasons, the parameters for IEC Publication 825 [16] Class 1 devices shall not be exceeded,
even under failure conditions.
7.2 Characteristics of the interface at the S reference point
B
For further study.
8 Physical medium characteristics of the UNI at 622 080 kbit/s
8.1 Characteristics of the interface at the T reference point
B
8.1.1 Bit rate and interface symmetry
The bit rate of the interface in at least one direction shall be 622 080 kbit/s. The following possible
interfaces have been identified:
a) an asymmetrical interface with 622 080 kbit/s in one direction and 155 520 kbit/s in the other
direction;
b) a symmetrical interface with 622 080 kbit/s in both directions.
If option a) is chosen, then the 155 520 kbit/s component shall comply with the characteristics of clause 7.
The nominal bit rate in free running clock mode shall be 622 080 kbit/s with a tolerance of
± 20 p.p.m.
8.1.2 Physical characteristics
For the purposes of this ETS, only the optical interface is considered.
8.1.2.1 Attenuation range
The attenuation of the optical path between the specification points S and R shall be in the range of 0 dB
to 7 dB (see subclause 7.1.2.2.3).

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ETS 300 300: February 1995
8.1.2.2 Transmission medium
The transmission medium shall consist of two single-mode fibres, according to ITU-T Recommendation
G.652 [1], one for each direction.
8.1.2.3 Optical parameters
8.1.2.3.1 Line coding
The line coding shall be binary NRZ.
The convention used for optical logic level is:
- emission of light for a binary ONE;
- no emission of light for a binary ZERO.
The extinction ratio shall be in accordance with ITU-T Recommendation G.957 [7], Application code I-4.
8.1.2.3.2 Operating wavelength
The operating wavelength shall be around 1 310 nm (second window).
8.1.2.3.3 Input and output port characteristics
The optical parameters will be in accordance with ITU-T Recommendation G.957 [7], Application code I-4.
The specification points associated with interface points I and I correspond to measurement reference
a b
points S and R, as defined in ITU-T Recommendation G.957 [7]. The optical parameters are specified for
the transmitter and receiver at these specification points and for the optical path between these
specification points, i.e. the connector at the interface is considered to be part of the equipment and not
part of the fibre installation.
8.1.2.4 Optical connectors
The presentation of interface point I at B-NT1 or B-NT2 is via a socket.
b
The presentation of interface point I at B-TE or B-NT2 is using either:
a
a) a socket, i.e. the connection is to be made to the equipment toward the network with a cable with
plugs on both ends; or
b) an integral connecting cord with plug on the free end.
8.1.2.5 Safety requirements
For safety reasons, the parameters for IEC Publication 825 [16] Class 1 devices shall not be exceeded,
even under failure conditions.
8.2 Characteristics of the interface at the S reference point
B
For further study.
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ETS 300 300: February 1995
9 Power feeding
9.1 Provision of power
The provision of power to the B-NT1 via the UNI is optional. If the power is provided via the UNI, the
following conditions shall apply:
- a separate pair of wires shall be used for the provision of power to the B-NT1 via the T reference
B
point;
- the power sink shall be fed by either:
- a source under the responsibility of the user when requested by the network provider;
- a power supply unit under the responsibility of the network provider connected to the mains
electric supply in the customer premises;
- the capability of the provision of power by the user side shall be available either:
- as an integral part of the B-NT2/B-TE; and/or
- physically separated from the B-NT2/B-TE as an individual power supply unit;
- a power source capable to feed more than one B-NT1 shall meet the requirements at each
individual B-NT1 power feeding interface at the same point in time;
- a short circuit or overload condition in any B-NT1 shall not affect the power feeding interface of the
other B-NT1's.
9.2 Power available at B-NT1
If the power of the B-NT1 is provided via the T reference point, the power available at the B-NT1 shall be
B
at least 15 W.
9.3 Feeding voltage
The feeding voltage at the B-NT1 shall be in the range of -20 V
...