ETSI ETS 300 299 ed.1 (1995-02)

SLOVENSKI STANDARD
01-december-2003
âLURNRSDVRYQRGLJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL%,6'1±'RVWRSGR
FHOLþQHJDXSRUDEQLãNHJDRPUHåMD±9PHVQLNLIL]LþQHSODVWL]DDSOLNDFLMHY%,6'1
Broadband Integrated Services Digital Network (B-ISDN); Cell based user network
access; Physical layer interfaces for B-ISDN applications
Ta slovenski standard je istoveten z: ETS 300 299 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 300 299
TELECOMMUNICATION February 1995
STANDARD
Source: ETSI TC-NA Reference: DE/NA-052511
ICS: 33.080
ISDN, interface, access
Key words:
Broadband Integrated Services Digital Network (B-ISDN);
Cell 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

Page 2
ETS 300 299: 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.

Page 3
ETS 300 299: 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 the 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.15
4.5.2 Network termination 2 for B-ISDN 16
.................................................................
4.5.3 Terminal equipment for B-ISDN.16
4.5.3.1 Terminal equipment type 1 for B-ISDN 16
................................
4.5.3.2 Terminal equipment type 2 for B-ISDN.17
4.5.4 Terminal adapter for B-ISDN.17
5 User network interface specifications 17
................................................................................................
5.1 Interface location with respect to reference configuration .17
5.2 Interface location with respect to the wiring configuration 17
.................................................
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 user network interface at 155 520 kbit/s 18
.............................
7.1 Characteristics of the interface at the T reference point .18
B
7.1.1 Bit rate and interface symmetry.18
7.1.2 Physical characteristics 18
.................................................................................
7.1.2.1 Electrical interface .18
7.1.2.1.1 Interface range 18
......................................
7.1.2.1.2 Transmission medium .18
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 EMC/EMI requirements .19
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
.....
Page 4
ETS 300 299: 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 and 622 080 kbit/s 25
.............................
10.3 Header error control . 25
10.3.1 Header error control functions 25
......................................................................
10.3.2 Header Error Control (HEC) sequence generation. 28
10.4 Idle cells . 28
10.5 Cell delineation and scrambling 29
........................................................................................
10.5.1 Cell delineation and scrambling objectives. 29
10.5.1.1 Cell delineation algorithm 29
....................................................
10.5.2 Cell delineation performance . 30
10.5.3 Scrambler operation . 30
10.5.3.1 Distributed sample scrambler (31st order). 30
10.5.3.2 Transmitter operation. 30
10.5.3.3 Receiver operation 31
..............................................................
10.5.3.4 State transition diagram and mechanism . 32
10.6 Cell availability performance . 33
11 UNI related OAM functions. 33
11.1 Transmission overhead allocation. 33
11.2 OAM cell identification 34
.......................................................................................................
11.3 Allocation of OAM functions in information field . 35
11.4 Maintenance signals 37
..........................................................................................................
11.5 Transmission performance monitoring. 38
11.6 Control communication . 38
12 Operational functions 38
........................................................................................................................
12.1 Definition of signals at the interface . 38
12.2 Definitions of state tables at network and user sides 38
........................................................
12.2.1 Layer 1 states on the user side of the interface. 39
12.2.2 Layer 1 states at the network side of the interface. 40
12.2.3 Definition of primitives 42
...................................................................................
12.2.4 State tables. 42
Annex A (informative): Impact of random bit errors on HEC performance 46
............................................

Page 5
ETS 300 299: February 1995
Annex B (informative): Impact of random bit errors on cell delineation performance .47
Annex C (informative): Distributed sample scrambler descrambler implementation example .48
History 50
..........................................................................................................................................................

Page 6
ETS 300 299: February 1995
Blank page
Page 7
ETS 300 299: 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 cell based user network access physical layer interfaces to be applied to the T , S
B B
reference points of the reference configurations of the Broadband Integrated Services Digital Network
(B-ISDN) User-Network Interface (UNI), for B-ISDN applications. It addresses the transmission system
structure that may be used at these interfaces as well as the implementation of the UNI related Operation
And Maintenance (OAM) functions at the cell based physical layer.
The production of this ETS has taken into account the recommendations given in CCITT
Recommendations I.413 [7] and I.432 [8].
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

Page 8
ETS 300 299: February 1995
Blank page
Page 9
ETS 300 299: 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) cell 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 and 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.957: "Optical interfaces for equipments and systems
relating to the synchronous digital hierarchy".
[4] ITU-T Recommendation I.113: "Vocabulary of terms for broadband aspects of
ISDN".
[5] CCITT Recommendation I.321: "B-ISDN protocol reference model and its
application".
[6] ITU-T Recommendation I.361: "B-ISDN ATM layer specification".
[7] CCITT Recommendation I.413 (1992): "B-ISDN user-network interface".
[8] CCITT Recommendation I.432 (1992): "B-ISDN user-network interface -
Physical layer specification".
[9] CCITT Recommendation I.610 (1992): "B-ISDN operation and maintenance
principles and functions".
[10] CCITT Recommendation X.200: "Reference model of Open System
Interconnection for CCITT Applications".
[11] I-ETS 300 404: "Broadband Integrated Services Digital Network (B-ISDN);
B-ISDN Operation And Maintenance (OAM) principles and functions".
[12] IEC Publication 825: "Radiation safety of laser products equipment classification
requirements and user's guide".
[13] IEC Publication 950: "Safety of information technology equipment, including
electrical business equipment".

Page 10
ETS 300 299: February 1995
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the definitions given in ITU-T Recommendation I.113 [4] apply, in particular
for the definitions of idle cell, valid cell and invalid cell. In addition, the following definition applies:
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
BER Bit Error Rate
B-ISDN Broadband Integrated Services Digital Network
B-NT B-ISDN Network Termination
B-TA B-ISDN Terminal Adaptor
B-TE B-ISDN Terminal Equipment
BIP Bit Interleaved Parity
CLP Cell Loss Priority
CMI Coded Mark Inversion
CRC Cyclic Redundancy Check
FERF Far End Receive Failure
HEC Header Error Control
LAN Local Area Network
NNI Network Node Interface
MA Medium Adaptor
MPH Management Physical Header
NRZ Non Return to Zero
OAM Operation and Maintenance
OSI Open System Interconnection
PH Physical Header
PM Physical Medium
p.p.m part per million
PRBS Pseudo Random Binary Sequence
STI Surface Transfer Impedance
TC Transmission Convergence
TFV Terminal Failure Voltage
UNA User Network Access
UNI User Network Interface
TFV Terminal Failure Voltage
Page 11
ETS 300 299: February 1995
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
S
R
B
TE2
or B-TA
B-TE2
Reference point
B-TA  Broadband terminal adaptor
B-TE  Broadband terminal equipment
B-NT  Broadband network termination
Functional group
Figure 1: B-ISDN reference configurations
In order to clearly illustrate the broadband aspects, the notations 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.
Figure 2 is subdivided into separate items as follows:
- figures 2a) and 2b) show separate interfaces at the S and T reference points;
B B
- figures 2c) and 2d) show an interface at S but not at T ;
B B
- figures 2e) and 2f) show an interface at T but not at S ;
B B
- figures 2g) and 2h) show separate interfaces at S, S and T ;
B B
- figures 2i) and 2j) show interfaces at S and T which are coincident.
B B
Page 12
ETS 300 299: February 1995
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
R T
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
R S
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

Page 13
ETS 300 299: 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)

Page 14
ETS 300 299: February 1995
c) multi-access 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: Medium Adaptor (MA): accommodates the specific topology of the distributed B-NT2.
The interface at W may include topology dependant elements and may be a non-
standardized interface.
NOTE 2: There will be a physical link between these two MAs 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: The 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 commonality 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 multi-access B-TE configurations. Requirements and
implementations of these functions are for further study.
Figure 3 (concluded): Examples of physical configurations for multipoint applications

Page 15
ETS 300 299: 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 the 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 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 commonality, in order to ensure that a simple broadband terminal may be
connected directly to the T interface.
B
The feasibility of achieving the needed commonality 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 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
This functional group includes functions broadly equivalent to layer 1 of the Open System Interconnection
(OSI) reference model. Examples of B-NT1 functions are:
- line transmission termination;
- transmission interface handling;
- cell delineation;
- OAM functions.
Page 16
ETS 300 299: February 1995
4.5.2 Network termination 2 for B-ISDN
This functional group includes functions broadly equivalent to layer 1 and higher layers of the CCITT
Recommendation X.200 [10] reference model. B-NT2 can be null in the case of commonality 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.
4.5.3 Terminal equipment for B-ISDN
This functional group includes functions broadly belonging to layer 1 and higher layers of the CCITT
Recommendation X.200 [10] 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
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 ETSs.
B B
Page 17
ETS 300 299: February 1995
4.5.3.2 Terminal equipment type 2 for B-ISDN
This functional group includes functions belonging to the functional group B-TE but with a broadband
interface that complies with interface recommendations other than the B-ISDN interface recommendations
or interfaces not included in CCITT Recommendations.
4.5.4 Terminal adapter for B-ISDN
This functional group includes functions broadly belonging to layer 1 and higher layers of the CCITT
Recommendation X.200 [10] reference model that allow a TE2 or a B-TE2 terminal to be served by a
B-ISDN user-network interface.
5 User network interface 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 side (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
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

Page 18
ETS 300 299: February 1995
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 ITU-T
Recommendation I.361 [6]. 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 ITU-T Recommendation
I.361 [6], § 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 [5].
7 Physical medium characteristics of the user network interface 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 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.

Page 19
ETS 300 299: February 1995
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 shall 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 shall 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 Ib at B-NT1 or B-NT2 shall be via a socket.
The presentation of interface point Ia at B-TE or B-NT2 shall be using either:
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], § 12.1.
7.1.2.1.6 EMC/EMI 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
cables is given in figure 6. For connectors, these template values shall be multiplied by 10 (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.

Page 20
ETS 300 299: February 1995
B
log  S TI
A
fff
log frequency
frequency (MHz):
STI value (W/m):
f = 0,1 A = 0,01
f = 100
f = 1 000 B = 1
The applicability of these values for microcoax cables is for further study.
Figure 6: Maximum STI values as a function of frequency
Receiver
Transmit BER
Transmission
signal under
+
cable
test
generator Analyser
TFV
Generator
Figure 7: Measurement configuration

Page 21
ETS 300 299: February 1995
TFV
level
dBV
A
A
F F F
frequency (MHz)
0 2
Figure 8: Terminal failure voltage frequency response
Table 1: Terminal failure voltage values
frequency (MHz) TFV amplitude (dBV)
(0 dBV = 1 V )
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 7.1.2.2.3.3).
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 [3], application code I-1.
7.1.2.2.3.2 Operating wavelength
The operating wavelength shall be around 1 310 nm (second window).

Page 22
ETS 300 299: February 1995
7.1.2.2.3.3 Input and output port characteristics
The optical parameters shall be in accordance with ITU-T Recommendation G.957 [3], application code I-
1. Some national application may use optical parameters for multi-mode fibres.
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 [3]. 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 Ib at B-NT1 or B-NT2 shall be via a socket.
The presentation of interface point Ia at B-TE or B-NT2 shall be using either:
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.
7.1.2.2.5 Safety requirements
For safety reasons, the parameters for IEC Publication 825 [12], 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 should comply with the characteristics as given
in clause 6.
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 7.1.2.3.3).

Page 23
ETS 300 299: 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 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 [3], 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 shall be in accordance with ITU-T Recommendation G.957 [3], 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 [3]. 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 Ib at B-NT1 or B-NT2 shall be via a socket.
The presentation of interface point Ia at B-TE or B-NT2 shall be using either:
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.
8.1.2.5 Safety requirements
For safety reasons, the parameters for IEC Publication 825 [12], 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.
Page 24
ETS 300 299: February 1995
9 Power feeding
9.1 Provision of power
The provision of power to the B-NT1 via the UNI network interface 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
The power available at the B-NT1 via the UNI shall be at least 15 W.
9.3 Feeding voltage
The feeding voltage at the B-NT1 shall be in the range of -20 V to -57 V relative to ground.
9.4 Safety requirements
In order to harmonize power source and sink requirements the following is required:
a) the power source shall be protected against short-circuits and overload;
b) the power sink of B-NT1 shall not be damaged by an interchange of wires.
With respect to the feeding interface of the power source, which is regarded as a touchable part in the
sense of IEC Publication 950 [13], the protection methods against electric shock specified in IEC
Publication 950 [13] may be applied.
10 Functions provided by the transmission convergence sublayer
10.1 Transfer capability
10.1.1 Interface at 155 52
...