1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T L.62TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2004) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Practical aspects of unbundling services by multiple operators in copper access networks ITU-T
2、Recommendation L.62 ITU-T Rec. L.62 (09/2004) i ITU-T Recommendation L.62 Practical aspects of unbundling services by multiple operators in copper access networks Summary In many countries, Other Licensed Operators (OLOs) are allowed to compete with the incumbent operator. This creates an environmen
3、t where a company has to install, operate and maintain its network bearing in mind that other networks exist right beside it, or even at the same location. In a number of countries, it is also determined that the operators should share some parts of the network with OLOs, in a transparent process to
4、 the users. This is called Unbundling of Network Elements or, in short, unbundling, and is a very complex task. Some new issues have to be taken into account to allow the accommodation of those operators sharing the same location to do so without problems. To guarantee an environment where operators
5、 interact but do not affect the Quality of Service provided by other operators, legal, regulatory and administrative statements must be followed by the correct technical solutions, which assure the network integrity, easy use of equipment and access to security. This Recommendation is intended to pr
6、ovide the guidelines to achieve these targets for the local loop in copper networks. Source ITU-T Recommendation L.62 was approved on 6 September 2004 by ITU-T Study Group 6 (2001-2004) under the ITU-T Recommendation A.8 procedure. Keywords Copper cable, ISDN, local loop, network element, shared net
7、work, unbundling, xDSL. ii ITU-T Rec. L.62 (09/2004) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for st
8、udying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study gr
9、oups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with
10、 ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provis
11、ions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such
12、 words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position
13、 concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected
14、 by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced
15、, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. L.62 (09/2004) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations 3 5 Topologies 4 5.1 Indoor . 4 5.2 Outdoor. 5 6 Issues related to unbundling . 5 6.1 Interfacing operators on the MDF 5 6.2 I
16、nterfacing operators on cabinets or closures . 6 6.3 Interfacing operators on aerial installations . 6 6.4 Interfacing operators on buried installations 6 6.5 Interfacing operators in the manhole 6 6.6 Interfacing operators on the customer premises. 6 6.7 Cable frequency spectrum management plan. 7
17、6.8 Installation and maintenance 7 7 Issues related to co-location . 7 7.1 Typical co-location inside MDF. 7 7.2 Virtual co-location inside MDF 8 7.3 Co-location outside MDF. 8 8 Shared sub-loops. 9 iv ITU-T Rec. L.62 (09/2004) Introduction Network elements can be unbundled in a number of ways which
18、 are described in this Recommendation. Co-location is also described, as it is intrinsically related to unbundling. Crucial aspects must be foreseen, e.g., the evolution of the optical access network, which reduces the copper network, getting closer to the customer premises. It may be difficult to c
19、hange the network topology maintaining services already provided by OLOs in the same network element. It must be noted that when multiple services are provided over the same network element, each service must not affect the Quality of Service provided by other operators and shall comply with the Rec
20、ommendations applicable for each service when provided alone. Also, a service must not interfere with other services in use, or which are planned to be used, in a network element. ITU-T Rec. L.62 (09/2004) 1 ITU-T Recommendation L.62 Practical aspects of unbundling services by multiple operators in
21、copper access networks 1 Scope This Recommendation relates to the technical aspects of copper local loop unbundling which, it should be noted are subject to national regulations. Although a number of network elements can be defined, this Recommendation focuses specifically on the copper local loop b
22、ecause it is the most prevalent worldwide. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations
23、and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published.
24、 The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation K.58 (2003), EMC, resistibility and safety requirements and procedures for co-located telecommunication installations. ITU-T Recommendation K.59 (
25、2003), EMC, resistibility and safety requirements and procedures for connection to unbundled cables. ITU-T Recommendation L.19 (2003), Multi-pair copper network cable supporting shared multiple services such as POTS, ISDN and xDSL. 2 ITU-T Rec. L.62 (09/2004) 3 Definitions This Recommendation define
26、s the following terms. For better understanding of the terms, the main types of unbundling of the local loop are outlined in Figure 1 and described below. See abbreviations on the next item. Figure 1/L.62 Typical types of unbundled network elements 3.1 full unbundling: OLO has direct access to the t
27、wisted copper pair and can use the pair to provide any service allowed (xDSL, voice), without interfering with other services provided in the same cable, usually associated with co-location of OLOs equipment. 3.2 line sharing: Voice service (POTS, PSTN) and data transmission services (xDSL, ISDN) ar
28、e provided using the same copper pair. Voice is provided in the lower frequency band and data transmission in the higher frequency band. Both operators must physically access the pair, and the OLOs equipment is usually housed in a co-location area inside the incumbents central office building. Split
29、ters have to be installed, both in the customers premises and in the central office, to guide the signals suitably to the computer and to the telephone terminal, and to their correspondent networks. 3.3 bitstream: Actually, this is not unbundling, but a higher layer service, with less physical conta
30、ct between the incumbent and the OLO. In this Recommendation, this term includes the wholesale services provided by the incumbent to other operators that, otherwise, would not have access to their customers. Typically, the incumbent operator installs and operates the network from the customer premis
31、es to the DSLAM, providing the OLO with a bundle of channels (usually STM-1) usually associated with a transportation service (back haul) to the nearest OLOs PoP. 3.4 co-location: An OLO may want to (or may be obliged to) rent space in the incumbents central office to install its own equipment. Figu
32、re 1 shows a typical co-location area inside the CO, with the OLOs DSLAM installed on it. Due to an eventual lack of suitable space, there are some different kinds of co-location arrangements. When some OLOs want to (or may be obliged to) use the same room (or cabinet), there is a “shared co-locatio
33、n“. A “virtual co-location“ takes place when the DSLAM belongs to the OLO, but is installed and operated by the incumbent. Also, equipment ITU-T Rec. L.62 (09/2004) 3 may be housed outside the incumbents building (remote co-location), in another building or in containers located in parking lots, for
34、 example. Another special situation, described in 3.5, occurs when an outdoor remote DSLAM is needed. 3.5 outdoor remote DSLAM: This is the toughest situation, requiring critical technical solutions. When a network has remote concentration (or switching) elements in cabinets along the copper loops,
35、it may be necessary to connect those elements to the OLOs network. Usually there is no space for co-location and the elements are in an aggressive environment. This connection can be a very challenging task, as the equipments of both operators may have to be able to accept external tie cables and/or
36、 have space inside to install the OLOs DSLAM. Other solutions may include connection of the incumbents cabinet to the OLOs cabinet, compatible printed circuit cards inserted in the incumbents remote equipment, and the transport of the signals by the incumbent to the OLOs nearest PoP. The physical ac
37、cess is an important issue that has to have a convenient solution, because of security matters. Special attention is needed when the insertion of signals is allowed at some point along the cable between the central office and the customers premises. Such signals may interfere in the other services a
38、lready provided on the same cable since they can be stronger than the others at the insertion point. 3.6 sub-loop: There are special circumstances, usually in long copper loops, where parts of the local loop are rented separately from each other. The individual sub-loop elements usually available ar
39、e feeders, distribution and concentration elements. Problems and solutions are similar to those listed for the outdoor remote DSLAM. 4 Abbreviations This Recommendation uses the following abbreviations:1ADSL Asymmetric Digital Subscriber Line CO Central Office DSLAM Digital Subscriber Line Access Mu
40、ltiplexer EMC Electromagnetic Compatibility EMI Electromagnetic Interference HDF Handover Distribution Frame HDSL High bit rate Digital Subscriber Line ISDN Integrated Services Digital Network LLU Local Loop Unbundling also called Unbundling of the Local Loop (ULL) MDF Main Distribution Frame NE Net
41、work Element NTP Network Termination Point OLO Other Licensed Operator PoP Point of Presence POTS Plain Old Telephone Service PSTN Public Switched Telephone Network SDSL Symmetric Digital Subscriber Line _ 1Extracted from ITUs abbreviations database (http:/www.itu.int/sancho). 4 ITU-T Rec. L.62 (09/
42、2004) SHDSL Single pair High speed Digital Subscriber Line SSDSL Synchronized Symmetrical Digital Subscriber Line STM Synchronous Transport Module UADSL Universal Asymmetric Digital Subscriber Line UNE Unbundling of Network Elements VDSL Very high-speed Digital Subscriber Line xDSL Any of the variou
43、s types of Digital Subscriber Lines 5 Topologies The connection between incumbent and OLO equipments can be done at points that depend on the topology of the network. The following items describe some recommended configurations. 5.1 Indoor SplitterDSL modem(a)X(b)X(c)X(d)X(e)X(f)XMDFDSLAMSplitter Ro
44、uter“ (1) Connection at corresponding to (c), (e) as shown in the figure above.(2) Splitter output correponding to (d) as shown in the figure above.(3) Output port of DSLAM corresponding to (f) as shown in the figure above.X indicates connection points.MDFLocal switchFigure 2/L.62 Typical DSL networ
45、k and indoor connection points ITU-T Rec. L.62 (09/2004) 5 5.2 Outdoor Cable distributionbox/manhole OtherlocationCentralofficeOther locationPossibility of sub-loop unbundlingDistribution boardFloor distribution boardFigure 3/L.62 Typical DSL network and outdoor connection points 6 Issues related to
46、 unbundling Specific rules must be agreed upon with all operators that share a network element. There should be security rules related to physical access, fire safety, electrical compatibility, EMC/EMI, etc. Information about that part of the network should be available, to avoid problems like inter
47、ruptions, interferences, etc. 6.1 Interfacing operators on the MDF Full access Shared accessLocal loopUnbundled local loopLocal loopUnbundled local loopMDFjumperLocalexchangeOLOequipmentLocalexchangeOLOequipmentsplitterMDFIncumbentMDFIncumbentMDFInternal cableInternal cableFigure 4/L.62 Typical MDF
48、connection points 6 ITU-T Rec. L.62 (09/2004) 6.2 Interfacing operators on cabinets or closures Full access Shared accessLocal loopUnbundled local loopLocal loopUnbundled local loopMDFjumperLocalexchangeOLOequipmentLocalexchangeOLOequipmentsplitterMDFIncumbentMDFIncumbentMDFExternal cableExternal ca
49、bleFigure 5/L.62 Typical cabinets and closures connection points 6.3 Interfacing operators on aerial installations This infrequent configuration needs further study. 6.4 Interfacing operators on buried installations This infrequent configuration needs further study. 6.5 Interfacing operators in the manhole Figure 6/L.62 Typical manhole connection points 6.6 Interfacing operators on the customer premises This subject is for further study. ITU-T Rec. L.62 (09/2004) 7 6.7 Cable frequency spectrum management plan The occupation of the frequ
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