1、 International Telecommunication Union ITU-T G.7042/Y.1305TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 2(08/2005)SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Data over Transport Generic aspects General SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTO
2、COL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Link capacity adjustment scheme (LCAS) for virtual concatenated signals Amendment 2 ITU-T Recommendation G.7042/Y.1305 (2004) Amendment 2 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NE
3、TWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIE
4、R TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND
5、DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 General G.7000G.7099 Transport network control aspects G.7700G.7799 ETHERNET OVER TRANSPORT
6、 ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.7042/Y.1305 (2004)/Amd.2 (08/2005) i ITU-T Recommendation G.7042/Y.1305 Link capacity adjustment scheme (LCAS) for virtual concatenated signals Amendment 2 Summary
7、This amendment clarifies the G.7042/Y.1305 LCAS wait-to-restore and hold-off SDL diagrams. Source Amendment 2 to ITU-T Recommendation G.7042/Y.1305 (2004) was approved on 22 August 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.7042/Y.1305 (200
8、4)/Amd.2 (08/2005) 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 studying technical, operating and ta
9、riff 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 groups which, in turn, produce Recom
10、mendations 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 ISO and IEC. NOTE In this Recomme
11、ndation, 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 provisions (to ensure e.g. interoperabil
12、ity 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 words does not suggest that complianc
13、e 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 concerning the evidence, validity or
14、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 by patents, which may be required to
15、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 2006 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the
16、 prior written permission of ITU. ITU-T Rec. G.7042/Y.1305 (2004)/Amd.2 (08/2005) iii CONTENTS Page 1) Summary. 1 2) Clause 6.1 Methodology. 1 3) Clause A.1 LCAS Protocol. 2 4) Clause A.3 Procedures state diagrams 2 5) New Appendix II 2 ITU-T Rec. G.7042/Y.1305 (2004)/Amd.2 (08/2005) 1 ITU-T Recomme
17、ndation G.7042/Y.1305 Link capacity adjustment scheme (LCAS) for virtual concatenated signals Amendment 2 1) Summary Change the Summary: This Recommendation specifies a methodology for dynamically and hitlessly change (i.e., increase and decrease) the capacity of a container that is transported in a
18、 generic transport network (e.g., over SDH or OTN network using Virtual Concatenation). In addition, the methodology also provides survivability capabilities, automatically decreasing the capacity if a member experiences a failure in the network, and increasing the capacity when the network fault is
19、 repaired. With the following text: This Recommendation specifies a methodology for dynamically changing (i.e., increasing and decreasing) the capacity of a container that is transported in a generic transport network (e.g., over SDH or OTN network using Virtual Concatenation). In general, this chan
20、ge of capacity does not affect the traffic. In addition, the methodology also provides survivability capabilities, automatically decreasing the capacity if a member experiences a failure in the network, and increasing the capacity when the network fault is repaired. 2) Clause 6.1 Methodology Change
21、clause 6.1: LCAS in the virtual concatenation source and sink adaptation functions provides a control mechanism to hitless increase or decrease the capacity of a VCG link to meet the bandwidth needs of the application. It also provides the capability of temporarily removing member links that have ex
22、perienced a failure. The LCAS assumes that in cases of capacity initiation, increase or decrease, the construction or destruction of the end-to-end path of each individual member is the responsibility of the Network and Element Management Systems. A VCG capacity increase or decrease can be initiated
23、 at either end. However, the initiation of a VCG capacity decrease at the Sk may result in temporary loss of data, see 6.5. With the following text: LCAS in the virtual concatenation source and sink adaptation functions provides a control mechanism to hitlessly increase or decrease the capacity of a
24、 VCG link to meet the bandwidth needs of the application. Hitless bandwidth modification can only be achieved when the transmission of the active members belonging to the VCG, before and after the bandwidth modification, is error-free (see Appendix II for details). It also provides the capability of
25、 temporarily removing member links that have experienced a failure. The LCAS assumes that in cases of capacity adjustment (i.e., creation, increase, decrease or deletion), the construction or destruction of the end-to-end path of each individual member is the responsibility of the Network and Elemen
26、t Management Systems. A VCG capacity increase or decrease can be initiated at either end. However, the initiation of a VCG capacity decrease at the Sk may result in temporary loss of data, see 6.5. 2 ITU-T Rec. G.7042/Y.1305 (2004)/Amd.2 (08/2005) 3) Clause A.1 LCAS Protocol Change first paragraph o
27、f clause A.1: The operation of LCAS is unidirectional. This means that in order to bidirectionally add or remove members, the procedure has to be repeated in the opposite direction. Note that these actions are independent of each other and are, therefore, not required to be synchronized. The scheme
28、allows hit-less addition and removal of bandwidth under control of a management system. Additionally, LCAS will autonomously remove failed members temporarily from the group. When the failure condition is remedied. LCAS will add the member back into the group. The removal of a member due to path lay
29、er failures will, in general, not be hit-less for the service carried over the virtual concatenated group. The autonomous addition, after a failure is repaired, is hit-less. With the following text: The operation of LCAS is unidirectional. This means that in order to bidirectionally add or remove me
30、mbers, the procedure has to be repeated in the opposite direction. Note that these actions are independent of each other and are, therefore, not required to be synchronized. When the transmission of members belonging to the VCG is error-free, the scheme allows hit-less addition and removal of bandwi
31、dth under control of a management system. Additionally, LCAS will autonomously remove failed members temporarily from the group. When the failure condition is remedied, LCAS will add the member back into the group. The removal of a member due to path layer failures will, in general, not be hit-less
32、for the service carried over the virtual concatenated group. The autonomous addition, after a failure is repaired, is hit-less. 4) Clause A.3 Procedures state diagrams Add the following note under Figure A.6 (HO procedure): NOTE There are particular circumstances that cause non-hit-less bandwidth mo
33、difications under hold-off periods. A description of the issue is described in Appendix II. 5) New Appendix II Add the following new appendix: Appendix II Non-hit-less bandwidth modifications during hold-off periods II.1 Introduction SDL diagram for the hold-off procedure described in clause A.3 sho
34、ws as possible input signal the MI-REMOVE command only, causing other inputs, that are not explicitly depicted, to be discarded. The LCAS state machine will, therefore, not act on CTRL words received during the hold-off periods, thus impacting the traffic. II.2 Removal of a group member at source Th
35、e removal action at source does not require synchronization between source and sink state machines and is, therefore, already performed at the source before signalling the change to the sink. Since the source already excluded the member from carrying payload, the sink should be able to react to this
36、 change immediately, even if it is currently in the hold-off state. If not, client payload will be lost until the timer expires. ITU-T Rec. G.7042/Y.1305 (2004)/Amd.2 (08/2005) 3 II.3 TSD conditions raised while performing ADD commands When performing a members addition at Sink, a CTRL=ADD is receiv
37、ed. Sink state will, therefore, move to the OK state and signal MST=OK to the source. The source will then move the member to the NORM state, signals CTRL=NORM/EOS and starts sending payload on this member. If, meanwhile, TSD is raised at the sink, the sink will have started a hold-off timer and is
38、not able to react to the CTRL=NORM/EOS. Client payload will be lost until the timer expires. II.4 Proposed enhanced HO procedure Even if the above-mentioned events are very limited in time and are characterized by a very low probability of occurrence, the HO procedure described in clause A.3 could o
39、ptionally be enhanced in order to allow hit-less capacity adjustments also in particular cases affected by transmission errors. The HO procedure SDL diagram to override the issue is reported below. Figure II.1/G.7042/Y.1305 Optionally enhanced hold-off procedure SDL diagram ITU-T Y-SERIES RECOMMENDA
40、TIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299 Network aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y
41、.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architecture, access, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interwork
42、ing Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 NEXT GENERATION NETWORKS Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y
43、.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Numbering, naming and addressing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Secu
44、rity Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. Printed in Switzerland Geneva, 2006 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff principles Series E Overall network opera
45、tion, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and tr
46、ansmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M Telecommunication management, including TMN and network maintenance Series N Maint
47、enance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph service
48、s terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
