SIST ETS 300 795:1999

SLOVENSKI STANDARD
SIST ETS 300 795:1999
01-julij-1999
/RNDOQDFHQWUDODLQGRVWRSQRRPUHåMH=DKWHYH]DL]YHGERLQQDþUWRYDQMH
REGHODYHNOLFDLQXSUDYOMDQMHQRVLOQH]YH]H
V interfaces at the digital Local Exchange (LE); Access Network (AN) supporting V5;
Transmission characteristics and performance design objectives for call handling and
bearer channel connection management
Ta slovenski standard je istoveten z: ETS 300 795 Edition 1
ICS:
33.040.35 Telefonska omrežja Telephone networks
SIST ETS 300 795:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 795:1999

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SIST ETS 300 795:1999
EUROPEAN ETS 300 795
TELECOMMUNICATION May 1998
STANDARD
Source: SPS Reference: DE/SPS-03027
ICS: 33.020
Key words: AN, LE, performance, V5 interface
V interfaces at the digital Local Exchange (LE);
Access Network (AN) supporting V5;
Transmission characteristics and performance design objectives
for call handling and bearer channel connection management
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
Internet: secretariat@etsi.fr - http://www.etsi.fr - http://www.etsi.org
Tel.: +33 4 92 94 42 00 - Fax: +33 4 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 1998. All rights reserved.

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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 Standards Making Support Dept." at the address shown on the title page.

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Contents
Foreword .5
Introduction.5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .8
3.1 Definitions .8
3.2 Abbreviations .8
4 Transmission characteristics.9
4.1 General .9
4.2 Characteristics of interfaces .9
4.2.1 PSTN access - Interface Z.9
4.2.2 ISDN access - V-type reference points/interfaces .9
4.2.3 Other analogue or digital access for leased lines.9
4.2.4 Interface V .9
5
4.3 Bearer channel signal transfer delay .9
5 Delay timing characteristics.10
5.1 General .10
5.2 Definition of test points and triggers .10
5.2.1 Test points at user ports.11
5.2.2 Test points at V interface(s) .11
5
5.2.2.1 V test point scenario .11
5.1
5.2.2.2 V test point scenario .12
5.2
5.2.3 Definition of trigger events.12
5.2.4 Signalling transfer delay .12
5.3 Delay probability characteristics.12
5.3.1 Direct impact on service provision at UNI .12
5.3.1.1 Signalling transfer delay .13
5.3.1.2 Processing non-intensive.13
5.3.1.3 Processing intensive.14
5.3.1.4 Non-critical delay timing.14
5.3.2 No direct impact on service provision at UNI .14
5.4 Load Testing on V AN.14
5.1
6 Call handling performance objectives .14
6.1 Premature release .14
6.2 Release failure.14
6.3 Other failures .15
7 Transmission performance objectives .15
Annex A (informative): Loading levels.16
A.1 Loading levels .16
A.1.1 "Upper Level" (see Q.543: Reference Load A).16
A.1.2 "Increased Level" (see Q.543: Reference Load B).16
A.2 Notes.16
Annex B (informative): Teletraffic aspects - background and teletraffic aspects of AN delay
performance objectives .17

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B.1 Reference loads. 17
B.2 Delay parameters . 17
Annex C (informative): Performance investigations . 18
C.1 General. 18
C.2 Load investigations in the AN . 18
C.2.1 General. 18
C.2.2 V case - non-concentrating interface . 19
5.1
C.2.3 V case - concentrating interface. 21
5.2
C.2.4 Practical load tests . 22
C.2.4.1 Traffic values . 22
C.2.4.2 Call generator adjustment. 23
C.2.4.3 Test evaluation . 24
C.3 Message delay considerations . 24
C.3.1 Introduction. 24
C.3.2 Definition of the trigger events.26
C.3.2.1 PSTN ports . 26
C.3.2.2 ISDN-BA Ds-data. 26
C.3.2.3 P-data in the D-channel (ISDN BA) . 27
C.3.2.4 Trigger signal production . 27
C.3.3 Signal transit time test. 28
C.3.3.1 Transit time within the AN. 28
C.3.3.2 Transit time via AN and LE. 28
C.3.4 Conclusions. 28
C.4 Abbreviations (used in annex C). 29
C.5 Symbols (used in equations) . 29
History. 30

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Signalling Protocols and
Switching (SPS) Technical Committee of the European Telecommunications Standards Institute (ETSI).
Transposition dates
Date of adoption of this ETS: 20 March 1998
Date of latest announcement of this ETS (doa): 31 August 1998
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 28 February 1999
Date of withdrawal of any conflicting National Standard (dow): 28 February 1999
Introduction
The work on a new V interface concept, initiated by a request from the ETSI Technical Assembly (TA),
was taken over by a Special Experts Group, set up by TC SPS and working under STC SPS3, with
experts from several STCs, e.g. SPS5, TM3 and NA4.
TC SPS identified in the terms of reference two interface concepts, one called the V interface, based
5.1
on a static multiplexing principle, and the other called the V interface, based on a dynamic,
5.2
concentrator type, principle.
The following set of standards form part of the V concept:
5
ETS 300 324-1 (1994): "V interface for the support of Access Network (AN)" (G.964);
5.1
ETS 300 347-1 (1994): "V interface for the support of Access Network (AN)" (G.965);
5.2
ETS 300 376-1 (1994): "Q interface specification to the access network for the configuration
3
management of V interface and associated user ports" (Q.57CM);
5
ETS 300 378-1 (1995): "Specifications of the Q interface to the access network for the support of V
3 5
interfaces; Fault and performance management of V interfaces and associated
5
user ports" (Q.57FPM).
This ETS includes a number of informative annexes:
Annex A: Loading Levels; Performance can be measured, independent of services
applied. Reference loads are specified for a characteristic mix of originating and
terminating call attempts.
Annex B: Teletraffic Aspects; Background and Teletraffic aspects of AN delay
performance objectives.
Annex C: Performance Investigations.

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1 Scope
This European Telecommunication Standard (ETS) specifies the performance design objectives of an
Access Network (AN) for call handling and bearer channel connection management. It is assumed that
the Local Exchange (LE) meets delay criteria as recommended by ITU-T Recommendation Q.543 [9].
Specified delays for the AN are additional to the ones for the LE. This ETS is applicable to both the V
5.1
interface as specified in ETS 300 324-1 [1]and V interface as specified in ETS 300 347-1 [2].
5.2
Relationship of design performance requirements to operational performance requirements as defined
within this ETS, should be considered as design objectives for systems under the conditions stated in this
ETS. These conditions are defined by such parameters as average circuit occupancy, busy hour call
attempts, etc. They should be distinguished from the operational performance requirements which AN and
service providers establish for remote access arrangements across interfaces at the V reference point
5
operating in their specific environment.
This standard is mainly intended for Access Networks involving optical or copper transmission media,
circuit based transfer mode, and PCM voice encoding. Other Access Network technologies, particularly
Radio technologies, may require further study.
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] ETS 300 324-1: "Signalling Protocols and Switching (SPS); V interfaces at the
digital Local Exchange (LE); V interface for the support of Access Network
5.1
(AN); Part 1: V interface specification".
5.1
[2] ETS 300 347-1: "Signalling Protocols and Switching (SPS); V interfaces at the
digital Local Exchange (LE); V interface for the support of Access Network
5.2
(AN); Part 1: V interface specification".
5.2
[3] ETS 300 463 (1996): "Transmission and Multiplexing (TM); Requirements of
passive Optical Access Networks (OANs) to provide services up to 2 Mbit/s
bearer capacity".
[4] ETS 300 011 (1992): "Integrated Services Digital Network (ISDN); Primary rate
user-network interface; Layer 1 specification and test principles".
[5] ETS 300 012 (1992): "Integrated Services Digital Network (ISDN); Basic user-
network interface Layer 1 specification and test principles".
[6] ETS 300 166 (1993): "Transmission and Multiplexing (TM); Physical and
electrical characteristics of hierarchical digital interfaces for equipment using the
2 048 kbit/s - based plesiochronous or synchronous digital hierarchies".
NOTE 1: This ETS is based on ITU-T Recommendation G.703 (1991).
[7] ETS 300 233 (1994): "Integrated Services Digital Network (ISDN); Access digital
section for ISDN primary rate".
NOTE 2: This ETS is based on ITU-T Recommendation G.962 (1993).
[8] ETS 300 297 (1995): "Integrated Services Digital Network (ISDN); Access digital
section for ISDN basic access".
NOTE 3: This ETS is based on ITU-T Recommendation G.960 (1993).

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[9] ITU-T Recommendation Q.543 "Digital exchange performance design
objectives".
[10] ITU-T Recommendation Q.551: "Transmission characteristics of digital
exchanges".
[11] ITU-T Recommendation Q.552: "Transmission characteristics at 2-wire
analogue interfaces of digital exchanges".
[12] ITU-T Recommendation Q.554 "Transmission characteristics at digital
interfaces of a digital exchanges".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS the following definitions apply:
Access Network (AN): A system implemented between the Local Exchange (LE) and the user, replacing
part or the whole of the local line distribution network.
bearer channel: A 64 kbit/s time slot in the V5 interface, allocated for a B-channel of an ISDN user port or
a PCM encoded 64 kbit/s channel for a PSTN user port.
control: Is concerned with status and control of user ports, V5 interface layer 1 and 2 establishment and
other common procedures.
Local Exchange (LE): An exchange on which user lines are terminated via an AN.
Q interface: A general term for the family of Q interfaces for the OAM&P of network elements (e.g., a
3
Q -AN or Q -LE interface).
3 3
V5 interface:
A general term for the family of V interfaces for connection of ANs to the LE (e.g., a V or
5.1
V interface).
5.2
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
AN Access Network
BCC Bearer Channel Connection
C-channel Communication channel
C-path Communication path
DC Direct Current (feeding, signalling)
FSM Finite State Machine
ISDN Integrated Services Digital Network
ISDN-BA ISDN-Basic Access
ISDN-PRA ISDN-Primary Rate Access
LE Local Exchange
NT1 Network Termination type 1
PCM Pulse Code Modulation
PSTN Public Switched Telephone Network
UNI User-Network Interface

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4 Transmission characteristics
4.1 General
The general definitions associated with transmission characteristics and transmission parameters from a
total perspective such as group delay and the transfer functions for jitter and wander are provided in ITU-T
Recommendations Q.551 [10], Q.552 [11] and Q.554 [12]. These Recommendations define, for any
bearer channel connection which may be set up, the necessary levels of transmission performance to
conform with overall objectives for the complete user-to-user connections in which an AN may be
involved.
4.2 Characteristics of interfaces
The interfaces taken into account are those defined in the V and V specifications. For voice-
5.1 5.2
frequency interfaces (i.e. Z and analogue leased lines), the electrical parameters refer to the appropriate
distribution frame, on the assumption that the length of the cabling between the distribution frame and the
AN does not exceed 100 m. For corresponding limitations on the location of digital interfaces, see
ETS 300 166 [6].
4.2.1 PSTN access - Interface Z
The interface Z provides for the connection of two-wire analogue subscriber lines and will carry signals
such as speech, voice-band data and multi-frequency push button signals, etc. In addition interface Z shall
provide for DC feeding the subscriber set and ordinary functions such as DC signalling, ringing and
metering, etc., where appropriate.
Detailed transmission characteristics for this interface are provided in ITU-T Recommendation Q.552 [11];
clauses "Characteristics common to all 2-wire analogue interfaces" and "Characteristics of interface Z".
4.2.2 ISDN access - V-type reference points/interfaces
The AN supports the following ISDN access types:
- ISDN basic access;
- ISDN primary rate access (not for V );
5.1
both with or without NT1 integrated in the AN.
For the detailed characteristics of these ISDN accesses reference should be made to the following
documents:
- ETS 300 297 [8] for ISDN basic access with NT1 separate for the AN;
- ETS 300 012 [5] for ISDN basic access with NT1 integrated in the AN;
- ETS 300 233 [7] for ISDN primary rate access with NT1 separate from the AN;
- ETS 300 011 [4] for ISDN primary rate access with NT1 integrated in the AN.
4.2.3 Other analogue or digital access for leased lines
The characteristics of these accesses are for further study.
4.2.4 Interface V
5
The V interface have transmission characteristics as given in ITU-T Recommendation Q.554 [12]; clause
5
"Interface characteristics at interface A", case of 2 048 kbit/s.
4.3 Bearer channel signal transfer delay
Bearer channel signal transfer delay is specified for the transmission capability of allocated B-channels
(ISDN access) or PCM encoded 64 kbit/s channels (PSTN access) and is defined in ETS 300 463 [3];
clause "Signal transfer delay".

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5 Delay timing characteristics
5.1 General
The delay timing characteristics are defined in terms of "trigger events" which can be observed at "test
points" specified for the AN configuration.
Figure 1 illustrates the general location of such "test points" for the definition of delay timings, i.e. at the
user ports and the V interface(s).
5
(V )
x
ISD N
BA/PRA
V
5
access
Access
Local
Network
Exchange
(AN)
Z
PSTN
access
test points test points
at user port at V interface(s)
5
Figure 1: Test points for AN configuration
For ISDN accesses the test point is related to the D-channel carrying all information types, i.e. Ds-data,
p-data and f-data.
At the V interface (protocol) information from different user accesses as well as from AN internal protocol
5
entities and FSMs is transported on the communication path (C-path). In order to enable an unambiguous
specification of delay timing parameters and values, separate test points for all the different information
types are defined. On the V interface separate logical test points are defined for each of the different
5
information types, i.e. ISDN Ds-data, ISDN p-data, ISDN f-data, PSTN signalling information, control
protocol, the link control protocol, etc.
5.2 Definition of test points and triggers
For the definition of delay parameters and values of the AN, the following general approach is used:
a) At PSTN user ports
For signals from the PSTN terminal the delay timing shall begin with the occurrence of the relevant line
signal change at the user port representing that particular PSTN signal, e.g. an on-hook should begin at
the time where the loop current falls below a certain value (i.e., any persistency checking time is
excluded).
For signals from the user port the delay timing shall terminate with the relevant line signal change at the
user port line side representing that particular PSTN signal.
This approach supports the definition of conformance statements and tests. It requires the definition of the
voltage and/or current values for the triggering of the measurement at the port on the basis of the national
PSTN protocol mapping implemented in the AN.

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b) At ISDN user ports
For signals from the ISDN terminal the delay timing shall begin with the end of the closing flag of the
relevant message in the D-channel at the ISDN user port.
For signals from the user port the delay timing shall terminate with the end of the opening flag of the
relevant message in the D-channel at the user port.
This approach limits the impact on the delay timing value from the message length as much as possible.
Furthermore the requirement shall be verified at the ISDN user ports having the relevant user-network
interface implemented. This avoids impact from the transmission system used and simplifies the
measurement.
c) At the V interface
5
For messages received from the LE the delay timing shall begin with the end of the closing flag of the
relevant message in the C-channel at the V interface.
5
For messages sent from the AN the delay timing shall terminate with the end of the opening flag of the
relevant message in the C-channel at the V interface.
5
This approach limits the impact on the delay timing values from the message length as much as possible.
5.2.1 Test points at user ports
At the user port the test point is defined either:
- on the analogue line wires of the PSTN access (interface Z); or
- on the D-channel of the ISDN access.
5.2.2 Test points at V interface(s)
5
At the V interface(s) separate test points are defined for the different types of data which are conveyed
5
over this interface as communication paths. This definition is made in order to avoid the overlapping effect
of queuing delays inside the AN.
According to the maximum number of 2 048 kbit/s interfaces and communication channels (C-channels)
defined for the individual types of V interfaces (i.e. V and V ) the following scenarios are presented.
5 5.1 5.2
5.2.2.1 V test point scenario
5.1
The V interface consists of a single 2 048 kbit/s link supporting the capability of three communication
5.1
channels.
The following test environment is defined for the V interface which requires that the individual types of
5.1
data to be conveyed over the V interface, are assigned through provisioning for each scenario to be
5.1
tested.
Table 1: Test scenario for the V interface
5.1
C-channel No. time slot provisioned for
1 16 control communication
2 15 type of data under test (note)
3 31 other types of data (note)
NOTE: Type of data: Ds-type data, PSTN signalling
information, p-type data, f-type data.

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5.2.2.2 V test point scenario
5.2
The V interface can have up to a sixteen 2 048 kbit/s links supporting a maximum capability of 16 x 3
5.2
communication channels.
The time slot allocation for physical communication channels as given in the V specification shall be
5.2
applied taking into account that the individual types of data to be conveyed over the V interfaces shall
5.2
be placed in separate logical C-channels.
In the case of only one 2 048 kbit/s link the test scenario (i.e. allocation of communication channels) may
be the same as given for the V interface.
5.1
5.2.3 Definition of trigger events
In defining delay timing performance parameters an AN reference event is the transfer of a discrete
(protocol) information element across an AN test point. Two classes of reference events are distinguished:
Entry event: a reference event that corresponds to a (protocol) information element entering the AN;
Exit event: a reference event that corresponds to a (protocol) information element exiting the AN.
5.2.4 Signalling transfer delay
For the delay value the occurrence of an entry event is defined to be the stop-flag of the received
message. The exit event is defined as the start-flag of the sent message.
If the signalling transfer delay were measured from start-of-receipt to start-of-sending, then ISDN
D-channel frame length would have to be accounted for.
For analogue signals, any persistence checking is excluded from the signal transfer delay.
5.3 Delay probability characteristics
This category of AN performance requirements, which is related to the logical communication channels
carrying the different information types of one or more communications paths, is split into two kinds of
classes:
1) having a direct impact on service provision at UNI;
2) not having direct impact on service provision at UNI - e.g. audit procedure process.
The delay timings are specified under certain loading conditions and are expressed where appropriate in
terms of mean and 95 % probability values. The term "mean" is taken to be the expected value of delay in
the statistical sense. The "95 % probability" value is taken as the limit within which 95 % of the delays fall.
Delays at higher loading levels are for further study.
Annex A defines the used "Loading Levels", whereas annex B gives "Background and Teletraffic aspects
of AN delay performance objectives".
5.3.1 Direct impact on service provision at UNI
This class of performance requirements covers the delay timing characteristics which have a direct impact
on the service provision at the User-Network Interface (UNI) as seen by a subscriber connected via the
AN to the LE.
Within this class of performance requirements the following delay timings are considered:
- ISDN D-channel information;
- PSTN signalling information;
- Control information;
- Link control information;
- Bearer channel connection (BCC) allocation/de-allocation protocol;
- Protection switch over protocol.

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According to the different information types a general classification can be made which defines:
1) Critical delay timings, e.g. ISDN Ds-data and PSTN signalling. For the critical delay timings three
types of performance parameters
...