1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.832 (I 0/98) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital transmission systems - Digital networks - Network capa bi I i ties and functions Transport of SDH elements on PDH
2、networks - Frame and multiplexing structures ITU-T Recommendation G.832 (Previously CCITT Recommendations) STD-ITU-T RECMN G.832-ENGL 1998 4862591 0656428 OT4 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS
3、INTERNATIONAL ANALOGUE CARRIER SYSTEM GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LI
4、NKS AND INTERCONNECTION WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY TESTING EQUIPMENTS TRANSMISSION MEDIA CHARACTERIS TICS DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS DIGITAL NETWORKS General aspects Design objectives for digital networks Quality and availability targe
5、ts Network capabi SDH network characteristics Telecommunications management network DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.IOO-G.199 G.200-G.299 G.300-G.399 G.400-G.449 G.450-G.499 G.700-G.799 G. 800-G. 899 G.800-G. 809 G. 8 1 O-G. 8 I 9 G. 820-G. 829 G.840-G . 849 G.850-G.859 G.900-G.999 For fu
6、rther details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN G-832-ENGL 1998 m YBb259L Ob5b429 T30 m 1 1/93 ITU-T RECOMMENDATION G.832 Initial version TRANSPORT OF SDH ELEMENTS ON PDH NETWORKS - FRAME AND MULTIPLEXING STRUCTURES Summary This Recommendation defines frame structures a
7、nd multiplexing arrangements for the transport of SDH elements over existing PDH transport networks operating at G.702 hierarchical rates of 34 368 kbit/s, 44 736 kbit/s, 97 728 kbits and 139 264 kbits. It is envisaged that these frame structures could, unless otherwise indicated, be used for the tr
8、ansport of other signals (e.g. ATM cells). History I Issue I Notes 02/98 Second revision: Modifications are made to subclauses 2.1.2,2.4.2,3.1.1 and 3.4.3 to support the Synchronization Status Message (SSM) instead of the timing marker in bit 8 of byte MA in the 34 368 and 139 264 kbitls signals. Th
9、e NR byte definition is modified and now aligned with the definition of byte N 1 in Annex D/G.707. First revision: Terms FEW and FEBE are replaced by RDI and REI. References to Recommendations G.708 and G.709 are replaced by references to Recommendation G.707. The trail trace identifier specificatio
10、n has been modified and refers to Recommendations G.707 and G.83 1. Source ITU-T Recommendation G.832 was revised by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 1 3h of October 1998. Recommendation G.832 (10/98) 1 FOREWORD ITU (International Tel
11、ecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on
12、them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approv
13、al of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation the
14、term recognized operating agency (ROA) includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms Administration, ROA and public correspondence are defined in the Constitution of the ITU (Geneva, 1992). INTELLECTUAL PROPERTY RI
15、GHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asser
16、ted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are caution
17、ed that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1999 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and micro
18、film, without permission in writing from the ITU. Recommendation G.832 (1098) 11 1 1.1 1.2 1.3 2 2.1 2.2 2.3 2.4 3 3.1 3.2 3.3 3.4 STD*ITU-T RECMN G.832-ENGL 1998 Y8b259L Ob5b43L b99 CONTENTS Introduction Scope References Abbreviations . Frame structures . Frame structure at 34 368 kbit/s . 2.1 . 1
19、General 2.1.2 Overhead allocation . Frame structure at 44 736 kbitk . 2.2.1 Intermediate 500 ps frame structure 2.2.2 Overhead allocation . Frame structure at 97 728 kbit/s . 2.3.1 General 2.3.2 Overhead allocation . Frame structure at 139 264 kbit/s . 2.4.1 General 2.4.2 Overhead allocation . Multi
20、plexing structures . Support of SDH elements in the 34 368 kbit/s frame structure 3.1.1 Coding of multiframe indicator for Tributary Unit multiframe indication . Support of SDH elements in the 44 736 kbit/s frame structure Support of SDH elements in the 97 728 kbit/s frame structure Support of SDH e
21、lements in the 139 264 kbits frame structure Multiplexing of 2 x TUG-3 and 5 x TUG-2 . Coding of multiframe indicator for Tributary Unit multiframe indication . 3.4.1 3.4.2 3.4.3 Multiplexing of 20 x TUG-2 . Annex A . Description of the 16-byte frame and CRC-7 calculation . w Page 1 1 1 1 2 2 2 3 4
22、4 5 5 5 6 7 7 7 9 9 10 Il 12 13 13 14 15 16 . Recommendation G.832 (10/98) 111 STD-ITU-T RECMN C-832-ENGL 1998 m 4862573 ObSb432 525 m Recommendation G.832 TRANSPORT OF SDH ELEMENTS ON PDH NETWORKS - FRAME AND MULTIPLEXING STRUCTURES (revised in 1998) 1 Introduction 1.1 Scope The purpose of this Rec
23、ommendation is to provide frame structures and multiplexing arrangements for the transport of SDH elements over existing PDH transport networks operating at various G.702 hierarchical rates. It is also envisaged that these frame structures could, unless otherwise indicated, be used for the transport
24、 of other signals (e.g. ATM cells). 1.2 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 o
25、ther references are subject to revision; all 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.
26、- ITU-T Recommendation G.707 (1 996), Network node interface for the Synchronous Digital Hierarchy (SOH), ITU-T Recommendation G.804 (1 998), A TM cell mapping into Plesiochronous Digital Hierarchy (PDH). CCITT Recommendation T.50 (1 992), International Reference Alphabet (IRA) (Formerly Internation
27、al Alphabet No. 5 or IA5) - Information technology - 7-bit coded character set for information interchange. - - 1.3 Abbreviations This Recommendation uses the following abbreviations: BIP-8 Bit Interleaved Parity-8 C-n Container of level n IEC Incoming Error Count LSB Least Significant Bit MFI Multi
28、Frame Indicator MSB Most Significant Bit PDH Plesiochronous Digital Hierarchy POH Path Overhead PTR PoinTeR RDI Remote Defect Indication REI Remote Error Indication Recommendation G.832 (10/98) 1 SDH Synchronous Digital Hierarchy SOH Section Overhead TTI Trail Trace Identifier TU-n TUG-n VC-n NOTE 1
29、 - The order of transmission of information in all diagrams in this Recommendation is first from left to right and then top to bottom. Within each byte the most significant bit is transmitted first. The most significant bit (bit 1) is illustrated at the left of all diagrams. NOTE 2 - In this Recomme
30、ndation the term “SDH elements“ indicates the various VCs with their associated pointers. Tributary Unit of level n Tributary Unit Group of level n Virtual Container of level n FA 1 EM TR MA NR GC - - - - 2 Frame structures The frame structures defined in this Recommendation are intended to be used
31、in a generic way. When implementing these frame structures, care should be taken to ensure that the performance of the frame alignment mechanism is not compromised by the payload content. FA2 530 octet payload 2.1 Frame structure at 34 368 kbit/s 2.1.1 General The basic frame structure at 34 368 kbi
32、t/s comprises 7 octets of overhead and 530 octets of payload capacity per 125 ps as shown in Figure 2-1. 59 columns T1302700-94 Figure 2-UG.832 - Frame structure at 34 368 kbit/s 2 Recommendation G.832 (10198) STD-ITU-T RECMN G-832-ENGL 1998 4Bb259L Ob56434 3TB GC 2.1.2 Overhead allocation The value
33、s and allocation of the overhead bytes are shown in Figure 2-2 and are described below. GC TI30271084 BIP-8 EM I I Trail Trace NR Figure 2-2/G.832 - Overhead allocation at 34 368 kbith FAl/FA2 Frame Alignment signal. This has the same pattern as A1/A2 defined in Recommendation G.707. EM Error Monito
34、ring, BIP-8. One byte is allocated for error monitoring. This function shall be a BIP-8 code using even parity. The BIP-8 is calculated over all bits, including the overhead bits, of the previous 125 ys frame. The computed BIP-8 is placed in the EM byte of the current 125 ps frame. TR Trail Trace. T
35、his byte is used to repetitively transmit a trail access point identifier so that a trail receiving terminal can verify its continued connection to the intended transmitter. The trail access point identifier shall use the access point identifier format as defined in clause 3/G.83 1. A 16-byte frame
36、is defined for the transmission of the access point identifier and this is described in Annex A. MA Maintenance and Adaptation byte Bit 1 RDI Bit 2 REI - This bit is set to “ 1 “ and sent back to the remote trail termination if one or more errors were detected by the BIP-8, and is otherwise set to z
37、ero. Bits 3 to 5 Payload type Code Signal O00 Unequipped O0 1 Equipped, non-specific O10 ATM O1 1 SDH TU-12s Bits 6-7 Multiframe indicator Recommendation G.832 (10/98) 3 Bit 8 This bit is used in a four-frame multiframe. The phase of the multiframe is determined by the value of MA bits 6 and 7, acco
38、rding to: Bit 6 Bit 7 Bit 8 O O SSM bit 1 (MSB) O 1 SSM bit 2 1 O SSM bit 3 1 1 SSM bit 4 (LSB) The four bits of the multiframe are allocated to the Synchronization Status Message (SSM). The coding of the SSM is given in Table YG.707. When intenvorking with “old“ equipment which used bit 8 as a timi
39、ng marker (non-multiframe), the “new“ equipment implementing the above requirement should be capable of being configured to transmit the “old“ requirement as given below: Bit 8, Timing marker. This bit is set to “O“ to indicate that the timing source is traceable to a Primary Reference Clock, and is
40、 otherwise set to “1“. NR Network Operator byte. This byte is allocated for maintenance purposes specific to individual Network Operators. Its transparency from Trail termination to Trail termination is not guaranteed. In the case where this byte is modified at an intermediate point in the trail, th
41、e EM byte must be appropriately corrected to ensure performance monitoring integrity. For Tandem Connection Maintenance, the byte is used in accordance with Annex D/G.707. General purpose communications channel (e.g. to provide datdvoice channel connection for maintenance purposes). 2.2 The basic fr
42、ame structure at 44 736 kbit/s is described in Recommendation G.704. Frame structure at 44 736 kbit/s 2.2.1 Since the 44 736 kbit/s frame structure is an asynchronous format with a nominal frame time of 106.402 ps, an intermediate 500 ps frame structure is defined below. This frame consists of 2736
43、bytes of payload, 4 framing bytes and 19 bytes of fixed stuff as shown in Figure 2-3. Intermediate 500 ps frame structure 4 Recommendation G.832 (10/98) STD=ITU-T RECMN G-832-ENGL 1998 4862571 065643b 170 23 rows 1 2736 bytes of payload capacity 144 rows T1304180-95 19 columns n Fixed stuff Figure 2
44、-3/6332 - Intermediate 500 ps frame structure for transport of SDH elements in the 44 736 kbit/s frame structure When this intermediate frame is combined along with the 44 736 kbits frame level stuffing and the 56 frame overhead bits of the C-bit parity format, the resultant signal will be 44 736 09
45、5 bits (within the range of the nominal 44 736 kbit/s f 20 ppm). 2.2.2 Overhead allocation The framing bytes and fixed stuff bytes are defined below, F1-11110110 F2-00101000 F3-11110110 F4-00101000 Fixed stuff- 11001100 2.3 Frame structure at 97 728 kbit/s 2.3.1 General Using the full 97 728 kbits r
46、ate, there are 1537 bytes available every 125 ps. As the net capacity of the Container-3 needs 756 bytes every 125 ps, two Container-3s can be allocated leaving 15 bytes every 125 ps for the overhead for the 97 728 kbitk signal and VC-3 POH functionality and for pointers as shown in Figure 2-4. Reco
47、mmendation G.832 (10198) 5 Ai: 11110110 A2: 001010MM (MM = 00/01/10/1 i) D: Data Communication Channel 1 84 M Ha Hb O0 H1 H1 O1 H2 H2 10 H3 H3 r il B2 KI r- J1 B3 - - Al, A2 D Ha, Hb J1 B3 C2/G1 F2 H4 I HI, H2, H3 Pointer KI RDI B2 BIP-8 1522 octet payload T1302720-94 Figure 2-4/G.832 - Frame struct
48、ure and overhead allocation for the 97 728 kbit/s 2.3.2 Overhead allocation The overheads and pointers are described below. Frame alignment signal: Al 11110110 A2 001010MM, where MM (= 00/01/10/11) is multifiame indicator for Ha and Hb bytes. A 64 kbits data communication channel. These multiframe s
49、tructured bytes have the following functionality: H1, H2, H3 B2 Reduced AU-3 pointer, which has the same function as defined in Recommendation G.707. Error monitoring, BIP-8. One byte is allocated for error monitoring of the 97 728 kbit/s signal. This function shall be a BIP-8 code using even parity. The BIP-8 is calculated over all bits of the previous 500 ps multiframe. The computed BIP-8 is placed in the B2 byte of the current 500 ps multifiame. Bit 8 is used for RDI. Bits 1-7 are reserved for future use. K1 VC-3 path trace as defined in Recommendation G.707. VC-3 pat
