SIST ETS 300 300 E2:2003

Broadband Integrated Services Digital Network (B-ISDN); Synchronous Digital Hierarchy (SDH) based user network access; Physical layer User Network Interfaces (UNI) for 155 520 kbit/s and 622 080 kbit/s Asynchronous Transfer Mode (ATM) B-ISDN applications

Functional and physical characteristics of the B-ISDN S(B) and T(B) reference points. Includes 2Mbit/s PDH.

Širokopasovno digitalno omrežje z integriranimi storitvami (B-ISDN) – Omrežni dostop za uporabnika sinhrone digitalne hierarhije (SDH) – Vmesniki uporabnik-omrežje (UNI) na fizični plasti za hitrosti 155 520 kbit/s in 622 080 kbit/s – Aplikacije v sistemu B-ISDN z asinhronim prenosnim načinom (ATM)

General Information

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 300 ed.2 (1997-04) - Broadband Integrated Services Digital Network (B-ISDN); Synchronous Digital Hierarchy (SDH) based user network access; Physical layer User Network Interfaces (UNI) for 155 520 kbit/s and 622 080 kbit/s Asynchronous Transfer Mode (ATM) B-ISDN applications

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 300 E2:2003
01-december-2003
âLURNRSDVRYQRGLJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL%,6'1±2PUHåQL
GRVWRS]DXSRUDEQLNDVLQKURQHGLJLWDOQHKLHUDUKLMH6'+±9PHVQLNLXSRUDEQLN
RPUHåMH81,QDIL]LþQLSODVWL]DKLWURVWLNELWVLQNELWV±$SOLNDFLMH
YVLVWHPX%,6'1]DVLQKURQLPSUHQRVQLPQDþLQRP$70
Broadband Integrated Services Digital Network (B-ISDN); Synchronous Digital Hierarchy
(SDH) based user network access; Physical layer User Network Interfaces (UNI) for 155
520 kbit/s and 622 080 kbit/s Asynchronous Transfer Mode (ATM) B-ISDN applications
Ta slovenski standard je istoveten z: ETS 300 300 Edition 2
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
SIST ETS 300 300 E2:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST ETS 300 300 E2:2003

---------------------- Page: 2 ----------------------

SIST ETS 300 300 E2:2003
EUROPEAN ETS 300 300
TELECOMMUNICATION April 1997
STANDARD Second Edition
Source: ETSI TC-TM Reference: RE/TM-03029
ICS: 33.020
Key words: B-ISDN, ISDN, UNI, ATM, SDH, interface, access
Broadband Integrated Services Digital Network (B-ISDN);
Synchronous Digital Hierarchy (SDH) based
user network access;
Physical layer User Network Interfaces (UNI) for 155 520 kbit/s
and 622 080 kbit/s Asynchronous Transfer Mode (ATM) B-ISDN
applications
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail]
Tel.: [phone] - Fax: [phone]
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 1997. All rights reserved.

---------------------- Page: 3 ----------------------

SIST ETS 300 300 E2:2003
Page 2
ETS 300 300: April 1997
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: 4 ----------------------

SIST ETS 300 300 E2:2003
Page 3
ETS 300 300: April 1997
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.12
4.3 Basic characteristics of the interfaces at T and S reference points.16
B B
4.3.1 Characteristics of the interfaces at 155 520 kbit/s .16
4.3.1.1 Interface at the T reference point.16
B
4.3.1.2 Interface at the S reference point.16
B
4.3.1.3 Relationship between interfaces at S and T .16
B B
4.3.2 Characteristics of the interfaces at 622 080 kbit/s .16
4.3.2.1 Interface at T reference point.16
B
4.4 Relationship between ISDN interfaces .16
4.5 Functional groups characteristics .16
4.5.1 Network termination 1 for B-ISDN (B-NT1).16
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 and S reference point.19
B 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.20
7.1.2.1.6 Electro-Magnetic Compatibility (EMC)
and Electro-Magnetic Interference
(EMI) requirements.20
7.1.2.2 Optical interface.22
7.1.2.2.1 Attenuation range.22
7.1.2.2.2 Transmission medium .22
7.1.2.2.3 Optical parameters .22
7.1.2.2.3.1 Line coding.22

---------------------- Page: 5 ----------------------

SIST ETS 300 300 E2:2003
Page 4
ETS 300 300: April 1997
7.1.2.2.3.2 Operating wavelength . 22
7.1.2.2.3.3 Input and output port characteristics. 22
7.1.2.2.4 Optical connectors . 22
7.1.2.2.5 Safety requirements . 22
7.1.3 Jitter and Wander . 23
8 Physical medium characteristics of the UNI at 622 080 kbit/s. 23
8.1 Characteristics of the interface at the T and S reference point . 23
B B
8.1.1 Bit rate and interface symmetry. 23
8.1.2 Physical characteristics . 23
8.1.2.1 Attenuation range. 23
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. 24
8.1.2.4 Optical connectors . 24
8.1.2.5 Safety requirements. 24
8.1.3 Jitter and Wander . 24
9 Power feeding. 24
9.1 Provision of power. 24
9.2 Power available at B-NT1. 25
9.3 Feeding voltage. 25
9.4 Safety requirements .25
10 Functions provided by the transmission convergence sublayer . 25
10.1 Transfer capability. 25
10.1.1 Interface at 155 520 kbit/s . 25
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
10.2.3 Interface structure for 622 080 kbit/s. 26
10.3 Header error control . 27
10.3.1 Header error control functions . 27
10.3.2 Header Error Control (HEC) sequence generation. 30
10.4 Idle cells . 30
10.5 Cell delineation and scrambling . 30
10.5.1 Cell delineation and scrambling objectives. 30
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 at the interface . 34
12.1.1 Signals defined in ITU-T Recommendation I.610. 34
12.1.2 Cell delineation signals . 35
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 . 36
12.2.3 Definition of primitives. 38
12.2.4 State tables. 38

---------------------- Page: 6 ----------------------

SIST ETS 300 300 E2:2003
Page 5
ETS 300 300: April 1997
Annex A (informative): Impact of random bit errors on cell delineation performance.42
Annex B (informative): Bibliography.43
History.44

---------------------- Page: 7 ----------------------

SIST ETS 300 300 E2:2003
Page 6
ETS 300 300: April 1997
Blank page

---------------------- Page: 8 ----------------------

SIST ETS 300 300 E2:2003
Page 7
ETS 300 300: April 1997
Foreword
This second edition European Telecommunication Standard (ETS) has been produced by the
Transmission and Multiplexing (TM) Technical Committee of the European Telecommunications
Standards Institute (ETSI).
This ETS has been established as a revision to the existing ETS 300 300, which defines the Synchronous
Digital Hierarchy (SDH) based user network access physical layer interfaces to be applied on 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.
Edition 1 of ETS 300 300 was produced by the Network Aspects (NA) Technical Committee of ETSI.
Transposition dates
Date of adoption: 4 April 1997
Date of latest announcement of this ETS (doa): 31 July 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 January 1998
Date of withdrawal of any conflicting National Standard (dow): 31 January 1998

---------------------- Page: 9 ----------------------

SIST ETS 300 300 E2:2003
Page 8
ETS 300 300: April 1997
Blank page

---------------------- Page: 10 ----------------------

SIST ETS 300 300 E2:2003
Page 9
ETS 300 300: April 1997
1 Scope
This second edition 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
B B
Services 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 Administration 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.
Edition 2 of this ETS defines newly considered points since the publication of edition 1, dealing particularly
with jitter characteristics at the B-UNI, sub-rates of STM-1 applied at the S and T reference points of the
B B
reference configurations of the B-ISDN SDH - based UNI (if required in this ETS), enhanced definitions
concerning the cell delineation algorithm and changes of the SDH overhead octet allocation at the B-UNI.
The production of this ETS has taken into account the recommendations given in ITU-T
Recommendation I.432.1 and I.432.2 [7].
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] ETS 300 166 (1993): "Transmission and Multiplexing (TM); Physical and
electrical characteristics of hierarchical digital interfaces for equipment using the
2048 kbit/s - based plesiochronous or synchronous digital hierarchies".
[3] ETS 300 232 Amendment 1 (1996): "Transmission and Multiplexing (TM);
Optical interfaces for equipments and systems relating to the Synchronous
Digital Hierarchy (SDH) [ITU-T Recommendation G.957 (1995), modified]".
[4] ITU-T Recommendation I.113: "Vocabulary of terms for broadband aspects of
ISDN".
[5] ITU-T Recommendation I.321: "B-ISDN protocol reference model and its
application".
[6] ITU-T Recommendation I.361: "B-ISDN ATM layer specification".
[7] ITU-T Recommendation I.432.1 (1995): "B-ISDN user-network interface -
Physical layer specification, General Characteristics".
ITU-T Recommendation I.432.2 (1995): "B-ISDN user-network interface -
Physical layer specification for 155 520 kbit/s and 622 080 kbit/s".
[8] ITU-T Recommendation I.610 (1992): "B-ISDN operation and maintenance
principles and functions".

---------------------- Page: 11 ----------------------

SIST ETS 300 300 E2:2003
Page 10
ETS 300 300: April 1997
[9] ITU-T Recommendation X.200: "Information technology - Open Systems
Interconnection - Basic reference model: The basic model".
[10] I-ETS 300 404: "Broadband Integrated Services Digital Network (B-ISDN);
B-ISDN Operation And Maintenance (OAM) principles and functions".
[11] IEC 825-1: "Safety of laser products: Part 1: Equipment classification
requirements and user's guide".
[12] IEC 950: "Safety of information technology equipment, including electrical
business equipment".
[13] ITU-T Recommendation G.707: "Network Node Interfaces for the Synchronous
Digital Hierarchy (SDH)".
[14] ITU-T Recommendation G.783: "Characteristics of synchronous digital hierarchy
(SDH) equipment functional blocks".
[15] ITU-T Recommendation G.825: "The control of jitter and wander within digital
networks which are based on the synchronous digital hierarchy (SDH)".
[16] ITU-T Recommendation G.958: "Digital line systems based on the synchronous
digital hierarchy for use on optical fibre cables".
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
AU Administrative Unit
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
BER Bit Error Ratio
BIP Bit Interleaved Parity
B-UNI Broadband integrated services digital network User Network Interface
CATV CAble TeleVision
CLP Cell Loss Priority
CMI Coded Mark Inversion
CRC Cyclic Redundancy Check
EMC Electro-Magnetic Compatibility
EMI Electro-Magnetic Interference
HEC Header Error Control
ISDN Integrated Services Digital Network
LAN Local Area Network
LCD Loss of Cell Delineation
LOF Loss Of Frame
LOP Loss Of Pointer
LOS Loss Of Signal
LSB Least Significant Bit
MA Medium Adaptor

---------------------- Page: 12 ----------------------

SIST ETS 300 300 E2:2003
Page 11
ETS 300 300: April 1997
MPH Management Physical Header
MSB Most Significant Bit
NNI Network Node Interface
NRZ Non Return to Zero
OAM Operation Administration and Maintenance
OCD Out of Cell Delineation
OSI Open System Interconnection
p.p.m part per million
PH Physical Header
PM Physical Medium
POH Path Overhead
PDU Protocol Data Unit
PRBS Pseudo Random Binary Sequence
PTR Pointer
RDI Remote Defect Indication
REI Remote Error Indication
SDH Synchronous Digital Hierarchy
SOH Section Overhead
STI Surface Transfer Impedance
STM Synchronous Transport Module
TC Transmission Convergence
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 Integrated Services Digital Network (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
B-TA
or
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

---------------------- Page: 13 ----------------------

SIST ETS 300 300 E2:2003
Page 12
ETS 300 300: April 1997
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: 14 ----------------------

SIST ETS 300 300 E2:2003
Page 13
ETS 300 300: April 1997
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
S T
R
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
R S
B
NOTE 1
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
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
NOTE 1: The need for an access to a TB-Reference point (between B-NT1 and B-NT2) is for further
study.
Figure 2: Examples of physical configurations for broadband user applications

---------------------- Page: 15 ----------------------

SIST ETS 300 300 E2:2003
Page 14
ETS 300 300: April 1997
a) Centralized 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 2)
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: 16 ----------------------

SIST ETS 300 300 E2:2003
Page 15
ETS 300 300: April 1997
c) Multi-access B-TE configurations:
c1) Generic configurations (see 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 the S
B B
interface. The functional characteristics of the interface, however, may be a 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: 17 ----------------------

SIST ETS 300 300 E2:2003
Page 16
ETS 300 300: April 1997
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 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 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 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 i
...