1、 International Telecommunication Union ITU-T Y.1720TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1(02/2008) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Operation, administration and maintenance Protection s
2、witching for MPLS networks Amendment 1 Recommendation ITU-T Y.1720 (2006) Amendment 1 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.
3、200Y.299 Network aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.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 A
4、rchitecture, access, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking 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
5、 NETWORKS Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.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 addres
6、sing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Y.1720 (2006)/Amd.1 (02/2008) i Recommendation ITU-T Y
7、.1720 Protection switching for MPLS networks Amendment 1 Summary Amendment 1 to Recommendation ITU-T Y.1720 (2006) removes the informative text of Appendix II concerning the packet 1+1 protection scheme. Source Amendment 1 to Recommendation ITU-T Y.1720 (2006) was agreed on 22 February 2008 by ITU-T
8、 Study Group 15 (2005-2008). ii Rec. ITU-T Y.1720 (2006)/Amd.1 (02/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization
9、Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying 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 e
10、very four years, establishes the topics for study by the ITU-T study groups 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 purv
11、iew, the necessary standards are prepared on a collaborative basis with 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 volu
12、ntary. However, the Recommendation may contain certain mandatory provisions (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
13、 negative equivalents are used to express requirements. The use of such 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
14、the use of a claimed Intellectual Property Right. ITU takes no position 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 Recommen
15、dation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/
16、www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T Y.1720 (2006)/Amd.1 (02/2008) 1 Recommendation ITU-T Y.1720 Protection switching for MPLS networks Amendment 1 This am
17、endment to Recommendation ITU-T Y.1720 (2006) removes the informative text of Appendix II concerning the packet 1+1 protection scheme. In clause 7.1.1.4, delete the last sentence, as follows: 7.1.1.4 Application architecture of unidirectional packet 1+1 protection switching Reference model Figure 9
18、illustrates a realization of the packet 1+1 protection scheme using sequence numbers as identifiers. After passing through the classifier, each packet that needs to be forwarded on the mated LSPs is assigned a distinct sequence number at the ingress node. This packet with the distinct identification
19、 is then duplicated and forwarded onto the two disjoint LSPs. On the egress node, a counter is used to keep track of the expected sequence number of the next packet. The details of an example implementation are described in Appendix II. Delete Appendix II and the bibliography. Printed in Switzerland
20、 Geneva, 2008 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and m
21、edia, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installatio
22、n and protection of cables and other elements of outside plant Series M Telecommunication management, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone trans
23、mission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services 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
