ETSI EG 201 900-1 V1.1.1 (2001-02)
Services and Protocols for Advanced Networks (SPAN); Narrowband Services over ATM; Loop Emulation Service (LES) using AAL2; Part 1: LES interface specification [ATM Forum Specification AF-VMOA-0145.000 (2000), modified]
Services and Protocols for Advanced Networks (SPAN); Narrowband Services over ATM; Loop Emulation Service (LES) using AAL2; Part 1: LES interface specification [ATM Forum Specification AF-VMOA-0145.000 (2000), modified]
DEG/SPAN-130104-1
Storitve in protokoli za napredna omrežja (SPAN) - Ozkopasovne storitve preko ATM - Storitev emulacije zanke (LES), ki uporablja AAL2 - 1. del: Specifikacija vmesnika LES [Specifikacija ATM foruma AF-VMOA-0145.000 (2000), modificirana]
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
01-november-2003
Storitve in protokoli za napredna omrežja (SPAN) - Ozkopasovne storitve preko
ATM - Storitev emulacije zanke (LES), ki uporablja AAL2 - 1. del: Specifikacija
vmesnika LES [Specifikacija ATM foruma AF-VMOA-0145.000 (2000), modificirana]
Services and Protocols for Advanced Networks (SPAN) - Narrowband Services over
ATM - Loop Emulation Service (LES) using AAL2 - Part 1: LES interface specification
[ATM Forum Specification AF-VMOA-0145.000 (2000), modified]
Ta slovenski standard je istoveten z: EG 201 900-1 Version 1.1.1
ICS:
33.040.35 Telefonska omrežja Telephone networks
SIST-V ETSI/EG 201 900-1 V1.1.1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
---------------------- Page: 2 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
ETSI EG 201 900-1 V1.1.1 (2001-04)
ETSI Guide
Services and Protocols for Advanced Networks (SPAN);
Narrowband Services over ATM;
Loop Emulation Service (LES) using AAL2;
Part 1: LES Interface specification
[ATM Forum Specification AF-VMOA-0145.000 (2000), modified]
---------------------- Page: 3 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
2 ETSI EG 201 900-1 V1.1.1 (2001-04)
Reference
DEG/SPAN-130104-1
Keywords
AAL, ATM, endorsement, V5 Interface
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE
Tel.: +33492 94 4200 Fax: +33493 65 4716
Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88
Important notice
Individual copies of the present document can be downloaded from:
http://www.etsi.org
The present document may be made available in more than one electronic version or in print. In any case of existing or
perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF).
In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive
within ETSI Secretariat.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at http://www.etsi.org/tb/status/
If you find errors in the present document, send your comment to:
editor@etsi.fr
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 2001.
All rights reserved.
ETSI
---------------------- Page: 4 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
3 ETSI EG 201 900-1 V1.1.1 (2001-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This ETSI Guide (EG) has been produced by ETSI Technical Committee Services and Protocols for Advanced
Networks (SPAN).
The present document is part 1 of a multi-part deliverable covering the Narrowband Services over ATM; Loop
Emulation Service (LES) using AAL2, as identified below:
Part 1: "LES interface specification [ATM Forum Specification AF-VMOA-0145.000 (2000), modified]";
Part 2: "Protocol Implementation Conformance Statement (PICS) proforma specification".
ETSI
---------------------- Page: 5 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
4 ETSI EG 201 900-1 V1.1.1 (2001-04)
1 Scope
The present document specifies the ETSI endorsement of the ATM Forum specification AF-VMOA-0145.000
(2000-07) 'Loop emulation service using AAL2'.
The present document provides appropriate selection or restriction of options and, if necessary, modifications and
amendments to the ATM Forum specification in order to meet the requirements of markets where ETSI V5 standards
are prevalent.
2 Endorsement notice
The elements of ATM-Forum specification 'Loop emulation service using AAL2 AF-VMOA-0145.000 (2000)', apply,
with the following modifications:
NOTE: New or modified text is indicated using sidebars. In addition, underlining and/or strike-out are used to
highlight detailed modifications where necessary.
Clause 1.3
Replace text in clause '1.3 Abbreviations' by:
For the purposes of the present document, the following abbreviations apply:AAL2 ATM Adaptation Layer type 2
AAL5 ATM Adaptation Layer type 5
AAL2 VCC an ATM VCC using AAL2
AAL5 VCC an ATM VCC using AAL5
ADPCM Adaptive Differential Pulse Code Modulation
ADSL Asymmetric Digital Subscriber Line
AINI ATM Inter Network Interface
AIS Alarm Indication Signal
AppId APPlication ID
AN Access Node
ANSI American National Standards Institute
ATM Asynchronous Transfer Mode
B-HLI Broadband - High Layer Information
BCC Bearer Channel Connection protocol
BRI Basic Rate Interface
CAS Channel Associated Signalling
CCS Common Channel Signalling
CDV Cell Delay Variation
CID AAL2 Channel Identifier
CMIP Common Management Information Protocol
CO Central Office
CO-IWF Central Office Interworking Function
CP-IWF Customer Premises Interworking Function
CPS Common Part Sublayer
CRV Call Reference Value
CSC Common Signaling Channel
DSS1 Digital Subscriber Signalling System number 1
DSS2 Digital Subscriber Signalling System number 2
DTMF Dual Tone Multi-Frequency
ELCP Emulated Loop Control Protocol
EOC Embedded Operations Channel
ETSI European Telecommunications Standards Institute
FAX Facsimile
FCS Frame Check Sequence
FSK Frequency Shift Keyed
GIT Generic Identifier Transport
HDLC High-level Data Link Control
ETSI
---------------------- Page: 6 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
5 ETSI EG 201 900-1 V1.1.1 (2001-04)
HDLC-F HDLC - Framing
HDSL High-speed Digital Subscriber Line
HFC Hybrid Fiber Coax
IDT Integrated Digital Terminal
IE Information Element
IEC International Electro-technical Commission
ILMI Integrated Local Management Interface
ISDN Integrated Services Digital Network
ISO International Standards Organization
ITU-T International Telecommunications Union, Telecommunications sector
IWF Interworking Function
LAPD Link Access Protocol for ISDN D-channel
LAPV5 Link Access Protocol for V5-interface
LAPV5-DL LAPV5 Data Link sublayer
LE Local Exchange
LES Loop Emulation Service
MBS Maximum Burst Size
MIB Management Information Base
OAM Operation Administration and Maintenance
OUI Organizational Unit Identifier
PBX Private Branch exchange
PCM Pulse Code Modulation
PDU Protocol Data Unit
PDV Packet Delay Variation
PNNI Private Network-to-Network Interface
PRS Primary Reference Source
PSTN Public Switched Telephone Network
PVC Permanent Virtual Circuit
RDI Remote Defect Indication
RDT Remote Digital Terminal
RFC Request For Comments
SAAL Signalling ATM Adaptation Layer
SAPI Service Access Point Identifier
SAR Segmentation And Reassembly
SCR Sustainable Cell Rate
SDU Service Data Unit
SHDSL Symmetric High-speed Digital Subscriber Line
SID Silence Insertion Descriptor
SigVCCI Signaling VCCI
SNI Service Node Interface
SNMP Simple Network Management Protocol
SPVC Soft Permanent Virtual Circuit
SSCS Service Specific Convergence Sublayer
SSSAR Service Specific SAR
SSTED Service Specific Transmission Error Detection
SSTED-CI SSTED - Congestion Indication
SSTED-LP SSTED - Loss Priority
SSTED-UU SSTED - User-to-User indication
SVC Switched Virtual Circuit
TDD Telecommunications Device for the Deaf
TDM Time Division Multiplexing
TED Transmission Error Detection
TMC Timeslot Management Channel
TMF Timeslot Management Function
UNI User Network Interface
UUI User-to-User Indication
VCC Virtual Channel Connection (where it may be a PVC, SPVC, or SVC)
VCCI VCC Identifier
xDSL any variety of Digital Subscriber Line, e.g. ADSL or SDSL
ETSI
---------------------- Page: 7 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
6 ETSI EG 201 900-1 V1.1.1 (2001-04)
Clause 1.8
Replace text in clause '1.8 CP-IWF functionality' by:
Depending on the configuration, a CP-IWF includes a subset of the following functions:
• physical layer interfaces to customer-located telephony equipment such as analog POTS, or basic rate ISDN or
channelized DS1;
• signalling Interworking, to receive signalling from and insert signalling into both the narrowband interfaces, and
the ATM broadband interfaces;
• SSCS User functions, including e.g. voice codecs for speech compression, echo cancellers and Fax
demodulation/remodulation units;
• AAL2 SSCS functions, to format User information into packets for transport on AAL2 connections;
• AAL2 CPS functions, for multiplexing AAL2 connections into ATM cells;
• ATM VCC Management, to allocate and deallocate ATM VCCs to distant CO-IWFs as needed to support the
traffic;
• AAL2 Channel Management, to allocate and de-allocate AAL2 channels to distant CO-IWFs as needed to
support the traffic;
• SAAL functions to support ATM UNI signalling activity for the establishment of SVCs on demand;
• a management interface to allow management of the telephony functions remotely from the CO-IWF.
Clause 1.9
Add the following introductory text in clause '1.9 References':
References maybemadeto:
a) specific versions of publications (identified by date of publication, edition number, version number, etc.), in
which case, subsequent revisions to the referenced document do not apply; or
b) all versions up to and including the identified version (identified by "up to and including" before the version
identity); or
c) all versions subsequent to and including the identified version (identified by "onwards" following the version
identity); or
d) publications without mention of a specific version, in which case the latest version applies.
A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
Clause 1.9.1
Replace text in clause '1.9.1 Normative' by:
The following references contain provisions that, through reference in this text, constitute provisions of this
specification. At the time of publication, the editions indicated were valid. All references are subject to revision, and
parties to agreements based on this specification are encouraged to investigate the possibility of applying the most
recent editions of the references indicated below.
[1] DSL Forum TR-017 (1999): "ATM over ADSL Recommendations".
[2] Void.ANSI T1.401-1993, Interface between carriers and customer installations - analog voice
grade switched access lines using loops-start and ground-start signaling.
[3] Void.ANSI T1.405-1996, Network-to-customer installation interfaces - direct-inward-dialing
analog voicegrade switched access using loop-reverse battery signaling.
ETSI
---------------------- Page: 8 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
7 ETSI EG 201 900-1 V1.1.1 (2001-04)
[4] Void.ANSI T1.409-1996, Network-to-customer installation interfaces - analog voice grade special
access lines using E&M signaling.
[5] Void.ANSI T1.602-1996, Integrated services digital network (ISDN) - Data-link layer signaling
specification for application at the user-network interface.
[6] Void.ANSI T1.607-1990 (R 1995) and ANSI T1.607a-1996, Digital subscriber signaling system
number 1 (DSS1) - layer 3 signaling specification for circuit-switched bearer services.
[7] ATM Forum af-pnni-0055.000 (1996): "Private Network-Network Interface Specification
Version 1.0".
[8] ATM Forum af-sig-0061.000 (1996): "ATM User-Network Interface (UNI) Signalling
Specification Version 4.0".
[9] ATM Forum af-ilmi-0065.000 (1996): "Integrated Local Management Interface (ILMI)
Specification Version 4.0".
[10] ATM Forum af-vtoa-0113.000 (1999): "ATM Trunking using AAL2 for Narrowband Services".
[11] ATM Forum af-cs-0125.000 (1999): "ATM Inter-Network Interface (AINI) Specification".
[12] ETSI ETS 300 012-1 (1998): "Integrated Services Digital Network (ISDN); Basic User-Network
Interface (UNI); Layer 1 specification".
[13] ETSI EN 300 324-1 (V2.1.1 20001999): "V interfaces at the digital Local Exchange (LE); V5.1
interface for the support of Access Network (AN); Part 1: V5.1 interface specification".
[14] ETSI EN 300 347-1 (V2.2.2): "V interfaces at the digital Local Exchange (LE); V5.2 interface for
the support of Access Network (AN); Part 1: V5.2 interface specification".
[15] ETSI ETS 300 402-1 (1995): "Integrated Services Digital Network (ISDN); Digital Subscriber
Signalling System No. 1 (DSS1) protocol; Data link Layer; Part 1: General aspects [ITU-T
Recommendation Q.920 (1993), modified]".
[16] ETSI ETS 300 402-2 (1995): "Integrated Services Digital Network (ISDN); Digital Subscriber
Signalling System No. 1 (DSS1) protocol; Data link Layer; Part 2: General protocol specification
[ITU-T Recommendation Q.921 (1993), modified]".
[17] IETF STD0002 (RFC1700) (1994): "Assigned numbers".
[18] ITU-T Recommendation G.991.2: "Single-Pair High-Speed Digital Subscriber Line (SHDSL)
transceivers".
[19] ITU-T Recommendation G.992.1 (1999): "Asymmetric Digital Subscriber Line (ADSL)
transceivers".
[20] ITU-T Recommendation G.992.2 (1999): "Splitterless Asymmetric Digital Subscriber Line
(ADSL) transceivers".
[21] ITU-T Recommendation G.964 (1994): "V-Interfaces at the digital local exchange (LE) -
V5.1 interface (based on 2 048 kbit/s) for the support of access network (AN)".
[22] ITU-T Recommendation G.965 (1995): "V-Interfaces at the digital local exchange (LE) -
V5.2 interface (based on 2 048 kbit/s) for the support of access network (AN)".
[23] ITU-T Recommendation I.363.2 (1997): "B-ISDN ATM Adaptation Layer (AAL) type 2
specification ".
[24] ITU-T Recommendation I.363.5 (1996): "B-ISDN ATM Adaptation Layer specification: Type 5
AAL".
[25] ITU-T Recommendation I.366.1 (1998): "Segmentation and Reassembly Service Specific
Convergence Sublayer for the AAL type 2".
ETSI
---------------------- Page: 9 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
8 ETSI EG 201 900-1 V1.1.1 (2001-04)
[26] ITU-T Recommendation I.366.2 (1999): "AAL Type 2 service specific convergence sublayer for
narrowband services".
[27] ITU-T Recommendation I.430 (1995): "Basic user-network interface - Layer 1 specification".
[28] ITU-T Recommendation I.432.1 (1999): "B-ISDN user-network interface- Physical layer
specification: General characteristics".
[29] ITU-T Recommendation I.432.2 (1999): "B-ISDN user-network interface - Physical layer
specification: 155 520 kbit/s and 622 080 kbit/s operation".
[30] ITU-T Recommendation I.432.3 (1996): "B-ISDN user-network interface - Physical layer
specification: 1544 kbit/s and 2048 kbit/s operation".
[31] ITU-T Recommendation I.432.4 (1999): "B-ISDN user-network interface - Physical layer
specification: 51 840 kbit/s operation ".
[32] ITU-T Recommendation I.432.5 (1997): "B-ISDN user-network interface - Physical layer
specification: 25 600 kbit/s operation".
[33] ITU-T Recommendation I.610 (1999): "B-ISDN operation and maintenance principles and
functions".
[34] ITU-T Recommendation Q.2931 (1995): "Broadband Integrated Services Digital Network
(B-ISDN) - Digital Subscriber Signalling System No. 2 (DSS 2) - User-Network Interface (UNI)
Layer 3 specification for basic call/connection control".
[35] VoidITU-T Q.2941.2, 1999, Broadband Integrated Services Digital Network (B-ISDN) -Digital
Subscriber Signalling System No. 2 (DSS 2): Generic identifier transport (Draft).
[36] ITU-T Recommendation Q.921 (1997): "ISDN user-network interface - Data link layer
specification".
[37] ITU-T Recommendation Q.931 (1998): "ISDN user-network interface layer 3 specification for
basic call control".
[38] ITU-T Recommendation V.8 (1998): "Procedures for starting sessions of data transmission over
the general switched telephone network".
[39] ITU-T Recommendation V.25 (1996): "Automatic answering equipment and general procedures
for automatic calling equipment on the general switched telephone network including procedures
for disabling of echo control devices for both manually and automatically established calls".
[40] VoidTelcordia Generic Requirements GR-303-CORE Issue 2, 1998, Integrated Digital Loop
Carrier System Generic Requirements, Objectives, and Interface.
NOTE: ITU-T Recommendations G.964 and G.965 are functionally equivalent to ETSI EN 300 324-1 and ETSI
EN 300 347-1 respectively. In cases where detail differences exist between the ITU-T and ETSI versions
of the specifications, the ETSI versions of the specifications should apply.
Clause 1.9.2
Replace text in clause '1.9.2 Informative' by:
[1] Void.ANSI T1.101-1994, Telecommunications - Synchronization Interface Standard.
[2] Void.ANSI T1.508-1992, Network Performance - Loss Plan for Evolving Digital Networks.
[3] DSL Forum TR-036WT-043 Rev 0.5 (2000): "Requirements for Voice over DSL".
[4] ITU-T Recommendation G.114 (1996): "One-way transmission time".
[5] ITU-T Recommendation G.131 (1996): "Control of talker echo".
[6] ITU-T Recommendation G.168 (1997): "Digital network echo cancellers".
ETSI
---------------------- Page: 10 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
9 ETSI EG 201 900-1 V1.1.1 (2001-04)
[7] VoidTelcordia Technical Reference TR-TSY-000008 Issue 2, 1987, Digital Interface between the
®
SLC 96 Digital Loop Carrier and a Local Digital Switch.
[8] VoidTelcordia Technical Reference TR-NWT-000057 Issue 2, 1993, Functional Criteria for
Digital Loop Carrier Systems.
[9] VoidTelcordia TR-NWT-000393, 1991, Generic Requirements For ISDN Basic Access Digital
Subscriber Lines.
[10] United Kingdom V5 PSTN Mapping Requirements SSPE/Specification/001-1.
[11] British Standard BS 7378-3 (1998): "Apparatus for connection to public telecommunications
systems using the Digital Access Signalling System No. 2 (DASS 2) via a 2 048 kbit/s CCITT
Recommendation G.703 interface. Requirements for apparatus for connection to Channel
Associated Signalling Systems (CASS)".
Clause 2
Replace introductory text in clause '2 Interfaces supported' by:
The present document identifies the user-side interfaces supported at the CP-IWF, and specifies the ATM interfaces at
both the CP-IWF and the CO-IWF. It does not define the interfaces on the network side of the CO-IWF, because it is
intended that the protocol operating between the IWFs should offer generic support for the delivery of narrowband
services at the CP-IWF user-side interfaces in a manner that is independent of the Service Node Interface at the
CO-IWF.
It is anticipated that some implementations of the CO-IWF will support narrowband Service Node interfaces to circuit-
switched voice networks in accordance with well known access network interface specifications such as Telcordia GR-
303, Telcordia TR-008, ETSI V5.1 (ITU-T Recommendation G.964) and ETSI V5.2 (ITU-T Recommendation G.965).
To assist implementors with the development of such devices, a series of informative appendices are included with the
present document which provide examples of mappings between the protocols that exist across these well-known V5
interfaces, and the protocols that are defined in the present document between CO-IWF and CP-IWF.
Clause 2.1
Replace text in clause '2.1 Physical layer' by:
The interface between a CO-IWF and the ATM network should be any ATM interface defined by the ATM Forum or
by the ITU-T recommendation I.432.x series of UNI recommendations, or the following interface types:
• ATM over ADSL in accordance with DSL Forum TR-017;
• other ATM physical layer specifications for SDSL, HFC and wireless transmission systems depending on the
application.
Examples of SDSL presently being standardized are:
• ITU-T SHDSL (Recommendation G.991.2, Single-pair high speed digital subscriber line (SHDSL) transceivers);
• ANSI HDSL2 (High bit rate Digital Subscriber Line - 2nd Generation (HDSL2));
• ETSI SDSL (Symmetric single pair high bit rate digital subscriber line (SDSL) transmission system on metallic
local lines).
ETSI
---------------------- Page: 11 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
10 ETSI EG 201 900-1 V1.1.1 (2001-04)
Clause 2.2
Replace text in clause '2.2 CP-IWF User side Interfaces' by:
A CP-IWF should support appropriate interfaces for connection to customer-located telephony equipment. These
interfaces may include analog telephony and basic rate ISDN, and DS1 with robbed-bit signaling.
Specifications for these interfaces include the following:
• Analog telephony interface in accordance with ANSI T1.401, ANSI T1.405, ANSI T1.409, Telcordia TR-NWT-
000057 or equivalent a national standard or equivalent network operator specification;
• Basic rate ISDN interface in accordance with ITU-T Recommendation I.430, Telcordia TR-NWT-000393, ETSI
ETS 300 012, or equivalent national standard or network operator specification.
Other line side customer interfaces depending on the application.
Clause 3.3
Replace introductory text in clause '3.3 Signalling' by:
The CP-IWF and the CO-IWF shall support the transport of signalling information across the ATM network between
the narrowband interface of the customer-located telephony equipment at the CP-IWF, and the Service Node Interface
at the CO-IWF.
This clause provides protocol reference models that illustrate the interworking between the narrowband user side
interfaces and the ATM network side interface at the CP-IWF.
Protocol reference models for the CO-IWF are not illustrated here because the present document does not define the
Service Node Interface at the CO-IWF. The ATM network side protocols are terminated at the CO-IWF in the same
manner as illustrated here for the CP-IWF. Example pProtocol reference models for the CO-IWF can be found in
informative appendixcesBand C that describes the operation of the CO-IWF with specific V5 based narrowband
Service Node Interfaces including GR-303 and V5.
Clause 3.7
Replace text in clause '3.7 Echo cancellation' by:
For voice applications, the combination of delay and echo causes an impairment to speech quality which is subjectively
determined and which may require measures to be taken to minimize the impact. Since most causes of delay cannot be
avoided or minimized, reduction of echo must be considered.
Delay is introduced into an end-to-end connection by a variety of factors including:
• Packetization.
• Compression algorithms.
• Physical transmission time.
• Switching of ATM cells in the network.
• Queuing.
• Build-out delay for accommodating PDV.
Echo is caused by:
• Hybrids used to go from 4-wire circuits to 2-wire circuits (typically at analog loops).
• Acoustical feedback at the end user's terminal (especially when the user places a telephone receiver down on a
hard surface).
ETSI
---------------------- Page: 12 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
11 ETSI EG 201 900-1 V1.1.1 (2001-04)
DSL Forum TR-036WT-043 suggests that the one-way delay introduced in the voice path by systems that implement
LES-AAL2 with typical DSL access connections is of the order of 20 ms to 25 ms. This is well in excess of the upper
limit of delay specified in ANSI T1.508 for digital access networks without echo cancellation. The use of echo
cancellation is therefore strongly advised.
Applicable ITU-T Recommendations such as G.131, G.114, G.165, G.168, and other references contain information on
this subject. Generally, the control of echo is best performed as close to the source of that echo as practicable. The
present document addresses neither the methods used to determine the need for nor the procedures for applying echo
cancellation. An IWF may support echo cancellation.
Clause 4.1.1
Replace text in clause '4.1.1 Application Identifier (AppId)' by:
The Application Identifier (AppId) specifies protocol combinations used between IWFs. Values are defined under the
ATM Forum OUI for the following:
• Loop Emulation Service using CAS (POTS only) without ELCP.
• Loop Emulation Service using PSTN signalling (POTS only) without ELCP.
• Loop Emulation Service using PSTN signalling (POTS only) with ELCP.
• Loop Emulation Service using DSS1 in support of BRI (BRI only) without ELCP.
• Loop Emulation Service using DSS1 in support of BRI (BRI only) with ELCP.
• Loop Emulation Service using CAS in support of POTS and DSS1 in support of BRI (without ELCP).
• Loop Emulation Service using PSTN signalling in support of POTS and DSS1 in support of BRI (without
ELCP).
• Loop Emulation Service using PSTN signalling in support of POTS and DSS1 in support of BRI (with ELCP).
• Loop Emulation Service using other variety of CCS.
• Unspecified mode of Loop Emulation Service.
Clause 5.1.1.1
Replace text in clause '5.1.1.1 Supervisory signalling' by:
Supervisory line states such as on-hook, off-hook, idle and ringing are conveyed between the CP-IWF and the CO-IWF
in the form of 4-bit codewords known as ABCD bits. Each value of the ABCD bit codeword represents a specific
supervisory line state. IWFs that support CAS shall transport the CAS ABCD bits to the other IWF as type 3 packets
using AAL2 in accordance with the procedures in Annex L of I.366.2. An IWF may have the capability to debounce the
CAS bits before transport over the ATM network in order to reduce unnecessary transmission.
The CP-IWF shall map the CAS ABCD bits associated with each AAL2 channel to analog line states at the POTS port
that corresponds with this channel. The mapping between analog line states and ABCD bit codewords is outside the
scope of this specification and is defined in the related CAS national standard (e.g. BS 7378-3 for the UK) or equivalent
network specification.shall be as defined in Telcordia GR-303-CORE tables 12-3 through 12-6.
Clause 5.1.2.1.3
Replace text in clause '5.1.2.1.3 Country/Operator specific usage of PSTN messages' by:
The PSTN message set defined in clause 13 of ETSI EN 300 324-1 and its associated information elements provides a
flexible and comprehensive solution to signalling analog line states, taking into account the many variations that are
seen in individual national implementations of analog POTS.
Most real implementations of POTS require only a small subset of the information elements that are specified for use
with PSTN protocol messages. Details of the PSTN messages and information elements that are needed for any specific
implementation should be available from the service provider that is making use of this implementation.
ETSI
---------------------- Page: 13 ----------------------
SIST-V ETSI/EG 201 900-1 V1.1.1:2003
12 ETSI EG 201 900-1 V1.1.1 (2001-04)
An example usage of PSTN messages to support analog POTS in North American markets is given in Appendix D.
Clause 9.2
Replace text in clause '9.2 Timing considerations' by:
A CO-IWF shall derive its timing from the Service Node interface.
A CP-IWF should derive its timing by one of the following methods.
• from the physical layer timing derived from the xDSL or HFC receiver interface, corrected if appropriate by
adequate Network Timing Reference information as specified by, for example, T1.413 Issue 2;
• by deducing timing information which is implicit in the rate of arrival of incoming AAL2 packets from the
CO-IWF.
In both cases, the objective is that the timing used by the CP-IWF should be traceable to a Primary Reference Source.
Information on the distribution of network timing may be found in ANSI T1.101 and ISO/IEC 11573. If the physical
layer timing derived from the xDSL or HFC receiver interface at the CP-IWF is not traceable to a PRS, then the
CP-IWF should not use this method to obtain timing information, but should instead deduce timing information from
the rate of arrival of AAL2 packets from the CO-IWF.
A CP-IWF may use a free-running local timing source. The use of a free-running clock less accurate than Stratum 3 is
not recommended since it may result in service impairments due to periodic clock slips.
Appendix A, clause A.1
Replace text in clause 'A.1 Operation of CO-IWF' by:
A CO-IWF may operate in "concentrated" or "non-concentrated" mode. In non-concentrated mode, each timeslot in
each TDM connection between CO-IWF and Service Node is statically allocated to a specific AAL2 channel. In
concentrated mode, the allocation of timeslots to AAL2 channels is carried out dynamically in the CO-IWF, as and
when originating or terminating call attempts occur.
The operation of the CO-IWF, in terms of the functionality depicted in figure A-1, is described in the following
paragraphs for the case of concentrated access mode. In the case of non-concentrated access mode, the Call Handling
function is null and signalling and bearer information is passed through the IWF according to a fixed mapping of
narrowband time slots to AAL2 channels.
E1/DS1 TDM trunks terminate on a Multiplexer/Demultiplexer function, which distributes the individual 64 kbit/s
channels between the trunks and the Switch function. The narrowband signalling associated with the individual
64 kbit/s channels, whether out-of band or -in-band is extracted via the Switch by the Signalling Interworking function.
This narrowband signalling includes both end-to-end signalling in CAS or CCS format that will be forwarded over the
ATM network to
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.