1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.7043/Y.1343TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2004) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments General SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NE
2、XT GENERATION NETWORKS Internet protocol aspects Transport Virtual concatenation of plesiochronous digital hierarchy (PDH) signals ITU-T Recommendation G.7043/Y.1343 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CI
3、RCUITS 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 CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE L
4、INKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM
5、 G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 General G.7000G.7099 Coding of analogue signals by pulse code modulation G.7100G.7199 Coding of analogue signals by me
6、thods other than PCM G.7200G.7299 Principal characteristics of primary multiplex equipment G.7300G.7399 Principal characteristics of second order multiplex equipment G.7400G.7499 Principal characteristics of higher order multiplex equipment G.7500G.7599 Principal characteristics of transcoder and di
7、gital multiplication equipment G.7600G.7699 Operations, administration and maintenance features of transmission equipment G.7700G.7799 Principal characteristics of multiplexing equipment for the synchronous digital hierarchy G.7800G.7899 Other terminal equipment G.7900G.7999 DIGITAL NETWORKS G.8000G
8、.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.7043/Y.1343 (07/2004) i ITU-T Recommendation G.7043/Y.1343 Virtual concatenation of plesiochronous digital hierarchy (PDH) signals Summary This Recommendation specifies the virtual concatenation of 1544, 2048,
9、 34 368 and 44 736 kbit/s PDH signals. This Recommendation makes use of the frame structures defined in ITU-T Recs G.704 and G.832. Source ITU-T Recommendation G.7043/Y.1343 was approved on 22 July 2004 by ITU-T Study Group 15 (2001-2004) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G
10、.7043/Y.1343 (07/2004) 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 studying technical, operating an
11、d 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 groups which, in turn, produce R
12、ecommendations 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 Rec
13、ommendation, 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. interoper
14、ability 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 c
15、ompliance 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, vali
16、dity 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 by patents, which may be requ
17、ired 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 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, wit
18、hout the prior written permission of ITU. ITU-T Rec. G.7043/Y.1343 (07/2004) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations 1 5 Conventions 2 6 Specification of the virtually concatenated interfaces 2 6.1 Interface at N 1544 kbit/s with virtual concatenation of a clear c
19、hannel payload . 2 6.2 Interface at N 2048 kbit/s with virtual concatenation of a clear channel payload . 4 6.3 Interface at N 34 368 kbit/s with virtual concatenation of a clear channel payload 5 6.4 Interface at N 44 736 kbit/s with virtual concatenation of a clear channel payload 7 iv ITU-T Rec.
20、G.7043/Y.1343 (07/2004) Introduction The basic PDH signal frame structures for 1544, 2048 and 44 736 kbit/s signals are defined in ITU-T Rec. G.704 and the octet structured 34 368 kbit/s is defined in ITU-T Rec. G.832. This Recommendation enhances the functions of these frame structures to support t
21、he virtual concatenation of these frame structures to form larger transport entities (containers). Only frame structures of the same type can be virtually concatenated together. This virtual concatenation supports the Link Capacity Adjustment Scheme (LCAS) specified in ITU-T Rec. G.7042/Y.1305. ITU-
22、T Rec. G.7043/Y.1343 (07/2004) 1 ITU-T Recommendation G.7043/Y.1343 Virtual concatenation of plesiochronous digital hierarchy (PDH) signals 1 Scope This Recommendation enhances the frame structures of PDH signals of 1544, 2048 and 44 736 kbit/s, as defined in ITU-T Rec. G.704, and the octet structur
23、ed 34 368 kbit/s, as defined in ITU-T Rec. G.832 to support virtual concatenation. Specifically, frame structures of the same type may be virtually concatenated together to form larger transport entities (containers). This virtual concatenation supports the Link Capacity Adjustment Scheme (LCAS) spe
24、cified in ITU-T Rec. G.7042/Y.1305. 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 and oth
25、er 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. The re
26、ference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation G.702 (1988), Digital hierarchy bit rates. ITU-T Recommendation G.704 (1998), Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit
27、/s hierarchical levels. ITU-T Recommendation G.707/Y.1322 (2003), Network node interface for the synchronous digital hierarchy (SDH). ITU-T Recommendation G.832 (1998), Transport of SDH elements on PDH networks Frame and multiplexing structures. ITU-T Recommendation G.7041/Y.1303 (2003), Generic fra
28、ming procedure (GFP). ITU-T Recommendation G.7042/Y.1305 (2004), Link capacity adjustment scheme (LCAS) for virtual concatenated signals. ITU-T Recommendation G.8040/Y.1340 (2004), GFP frame mapping into plesiochronous digital hierarchy (PDH). 3 Definitions This Recommendation defines the following
29、term: 3.1 nibble: A group of four bits. 4 Abbreviations This Recommendation uses the following abbreviations: CTRL Control field sent from source to sink DNU Do Not Use EOS End of Sequence GFP Generic Framing Procedure 2 ITU-T Rec. G.7043/Y.1343 (07/2004) GID Group Identification LCAS Link Capacity
30、Adjustment Scheme MFI MultiFrame Indicator MST Member Status NORM Normal Operating Mode PDH Plesiochronous Digital Hierarchy RS-Ack Re-sequence Acknowledge SQ Sequence Indicator VCG Virtual Concatenation Group VLI Virtual concatenation and LCAS Information 5 Conventions The order of transmission of
31、information in all the diagrams in this Recommendation is first from left to right and then from top to bottom. Within each byte or nibble the most significant bit is transmitted first. The most significant bit (bit 1) is illustrated at the left in all the diagrams. 6 Specification of the virtually
32、concatenated interfaces 6.1 Interface at N 1544 kbit/s with virtual concatenation of a clear channel payload 6.1.1 Frame and multiframe format The multiframe structure for the 24-frame multiframe as described in ITU-T Rec. G.704 shall be used. The first octet following the first framing bit of the m
33、ultiframe is used to carry the concatenation overhead for each 1544 kbit/s signal, as illustrated in Figure 6-1. This octet is reserved for all values of N (N = 116). G.7043-Y.1343_F6-1.123452324Concatenation overhead octet125 sFrame numberFFFFFFFFigure 6-1/G.7043/Y.1343 Concatenation overhead locat
34、ion for the N 1544 kbit/s signal 6.1.2 Concatenation of N 1544 kbit/s signals The concatenation overhead octet allows the virtual concatenation of N 1544 kbit/s signals to form a single channel referred to as a virtual concatenation group (VCG). The payload container bandwidth of the resulting VCG i
35、s N 1536 (64/24) kbit/s N 1533 kbit/s. Client signals are mapped into the N 1544 kbit/s signal members of the VCG on an octet-wise, round robin basis. The round robin sequence follows the ascending order of the per-member sequence numbers that are ITU-T Rec. G.7043/Y.1343 (07/2004) 3 communicated in
36、 each members concatenation overhead octet. For example, if a data packets octet 1 is mapped into the 1544 kbit/s signal with sequence number 0, the next packet octet is mapped into the 1544 kbit/s signal with sequence number 1, etc. Up to sixteen 1544 kbit/s signals can be virtually concatenated in
37、to a single VCG. In general, the virtual concatenation and associated Link Capacity Adjustment Scheme (LCAS) functionality and definitions are the same as those specified for SDH virtual containers in ITU-T Rec. G.707/Y.1322. The areas in which they differ are specified in this Recommendation. 6.1.2
38、.1 Concatenation overhead octet definition The concatenation overhead octet is time-multiplexed to carry the overhead required for virtual concatenation. This time multiplexing takes the form of a 16-nibble VLI that is transmitted one nibble per concatenation overhead octet. The concatenation overhe
39、ad octet contains one nibble for the VLI and one nibble for the MFI1. The contents and format of the concatenation overhead octet and VLI are shown in Figure 6-2. Concatenation overhead octet definition Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Control packet MFI1 MST (bits 1-4) 1 0 0 0 MST (b
40、its 5-8) 1 0 0 1 0 0 0 RS-ACK 1 0 1 0 Reserved (0000) 1 0 1 1 Reserved (0000) 1 1 0 0 Reserved (0000) 1 1 0 1 Reserved (0000) 1 1 1 0 SQ bits 1-4 1 1 1 1 MFI2 MSBs (bits 1-4) 0 0 0 0 MFI2 LSBs (bits 5-8) 0 0 0 1 CTRL 0 0 1 0 0 0 0 GID 0 0 1 1 Reserved (0000) 0 1 0 0 Reserved (0000) 0 1 0 1 C1C2C3C40
41、 1 1 0 C5 6 7 80 1 1 1 Figure 6-2/G.7043/Y.1343 Virtual concatenation control packet format for N 1544/2048 kbit/s signals The definitions of the fields within the control packet are given in ITU-T Rec. G.7042/Y.1305. MFI1 is the least significant four bits of the concatenation multiframe count and
42、is incremented once per concatenation overhead octet with its LSB located in bit 8. The Cnbits are the CRC check over the control packet, with C1being the MSB of the CRC. CRC generator polynomial is x8+ x2 + x + 1, and the calculation method is specified in ITU-T Rec. G.7042/Y.1305. The member statu
43、s (MST) information is time-multiplexed across multiple control packets as determined by the MFI2 LSB value. This time-sharing forms a member status multiframe that is specified in Figure 6-3. 4 ITU-T Rec. G.7043/Y.1343 (07/2004) VLI octet MFI2 bit 8 (LSB) value Bit 1 Bit 2 Bit 3 Bit 4 0 1 2 3 0 4 5
44、 6 7 8 9 10 11 1 12 13 14 15 Member numbers Figure 6-3/G.7043/Y.1343 Member status bit assignments for N 1544/2048 kbit/s signals 6.1.2.2 Differential delay detection All N 1544 kbit/s member signals that constitute a VCG are aligned at their transmission from the VCG source with respect to their 15
45、44 kbit/s clock frequency, PDH signal frame and multiframe, MFI1 and MFI2. The VCG sink can determine the differential delay that the different members encountered in the network by comparing their respective MFI1 and MFI2 values, and performing the proper realignment. Note that the four MSBs of MFI
46、2 are not used for differential delay compensation. The maximum differential delay that can be detected is (256)(24)(125s)/2 = 384 ms. 6.2 Interface at N 2048 kbit/s with virtual concatenation of a clear channel payload 6.2.1 Frame and multiframe format The basic frame and 16-frame multiframe struct
47、ure at 2048 kbit/s as described in ITU-T Rec. G.704 shall be used. The time slot 1 of the first frame of the multiframe is used to carry the concatenation overhead for each 2048 kbit/s signal, as illustrated in Figure 6-4. This octet is reserved for all values of N (N = 116). G.7043-Y.1343_F6-4.1234
48、51516Concatenation overhead octet125 sFramenumberT.S.0T.S.0T.S.0T.S.0T.S.0T.S.0T.S.0Figure 6-4/G.7043/Y.1343 Concatenation overhead location for the N 2048 kbit/s signal 6.2.2 Concatenation of N 2048 kbit/s signals The concatenation overhead octet allows the virtual concatenation of N 2048 kbit/s si
49、gnals to form a single channel referred to as a virtual concatenation group. The payload container bandwidth of the resulting VCG is N 1984 (64/16) kbit/s = N 1980 kbit/s. Client signals are mapped into the N 2048 kbit/s signal members of the VCG on an octet-wise, round robin basis. The round robin sequence follows the ascending order of the per-member sequence numbers that are communicated in each members concatenation overhead octet. For example, if a data packets octet 1 is mapped i
