1、STD-ETSI ETS 300 337-ENGL 1777 3Li00855 0398892 qO1 ETS 300 337 June 1997 Second Edition Source: ETSI TC-TM Reference: RE/TM-03056 ICs: 33.020 Key words: Transmission, ATM, SDH, transport Transmission and Multiplexing (TM); Generic frame structures for the transport of various signals (including Asy
2、nchronous Transfer Mode (ATM) cells and Synchronous Digital Hierarchy (SDH) elements) at the ITU-T Recommendation G.702 hierarchical rates of 2 048 kbit/s, 34 368 kbits and 139 264 kbit/s ETSI European Telecommunications Standards institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis C
3、EDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat etsi.fr Tel.: +33 4 92 94 42 O0 - Fax: +33 4 93 65 47 16 Copyright Notification: No part may be reproduced except as authorized by written p
4、ermission. The copyright and the foregoing restriction extend to reproduction in all media. O European Telecommunications Standards Institute 1997. All rights reserved. STD-ETSI ETS 300 337-ENGL 1777 3400855 0378873 348 Page 2 ETS 300 337: June 1997 Whilst every care has been taken in the preparatio
5、n and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title page. STDOETSI EIS 300 337-ENGL 1997 W 3400855 0198899 28Li M Page
6、3 ETS 300 337: June 1997 Contents Foreword . ._. 5 1 2 3 4 5 6 7 Scope . 7 Normative references . ._._ 7 . Definitions and abbreviations 7 Definitions ._ - . 7 3.1 3.2 Abbreviations . 8 . Frame structure at 2 048 kbit/s . 8 4.1 Basic frame structure . 8 4.2 Support of ATM cells in 2 048 kbit/s 8 Fra
7、me structure at 34 368 kbitls 9 5.1 Basic frame structure . _ 9 5.1.1 General 9 5.1.2 Path overhead . 10 Support of ATM cells in 34 368 kbit/s 12 Support of 14 SDH TU-12s in 34 368 kbi/s . 12 5.3.1 5.2 5.3 Coding of multiframe indicator for TU multiframe indication . 13 Frame structure at 139 264 kb
8、iffs . 14 6.1 Basic frame structure . . 14 6.1.1 General 14 6.1.2 Path overhead . 15 Support of ATM cells in 139 264 kbit/s 17 Support of SDH elements in 139 264 kbit/s . 18 6.3.1 6.3.2 6.3.3 6.2 6.3 Coding of multiframe indicator for TU multiframe indication . 18 Support of 2 x TUG-3 and 5 x TUG-2
9、. 18 Support of 20 x TUG-2 18 Conformance testing . 20 Annex A (informative: A.l Functions specific to the support of ATM cells . 21 Cell rate adaptation . 21 A.2 Header Error Control (HEC) generation . 21 A.3 Cell delineation . 21 A.4 Cell header verification and extraction 21 Annex B (informative)
10、: Bibliography ._ . 22 History STD-ETSI ETS 300 337-ENGL 3777 = 3i.100855 0378875 330 = Page 5 ETS 300 337: June 1997 Foreword This second edition European Telecommunication Standard (ETS) has been produced by the Transmission and Multiplexing (TM) Technical Committee of the European Telecommunicati
11、ons Standards Institute (ETSI). This ETS specifies generic frame structures for the transport of various signals at the ITU-T Recommendation G.702 l hierarchical rates of 2 048 kbit/s, 34 368 kbitls and 139 264 kbits. The support of Asynchronous Transfer Mode (ATM) cells and Synchronous Digital Hier
12、archy (SDH) Tributary Units (TUS) in the Plesiochronous Digital Hierarchy (PDH) bit rates is also covered in this ETS. This ETS takes into account the recommendations given in ITU-T Recommendation G.804 (annex 6.2) and G.832 (annex B.3) - see annex B (Bibliography) for details. Transposition dates D
13、ate of adoption: Date of latest announcement of this ETC (doa): 7 March 1997 30 September 1997 Date of latest publication of new National Standard or endorsement of this ETS (dop/e): 31 March 1998 Date of withdrawal of any conflicting National Standard (dow): 31 March 1998 Previous page is blank STD
14、-ETSI ETS 300 337-ENGL 1997 m 3400855 Ol19889b 057 m Page 7 ETC 300 337: June 1997 1 Scope This second edition European Telecommunication Standard (ETS) specifies generic frame structures for the transport of various signals at the ITU-T Recommendation G.702 l hierarchical rates of 2 048 kbii/s, 34
15、368 kbit/s and 139 264 kbit/s. The support of Asynchronous Transfer Mode (ATM) cells and Synchronous Digital Hierarchy (SDH) Tributary Units (TUS) in the Plesiochronous Digital Hierarchy (PDH) bit rates is covered in this ETS. Functions specific to the support of ATM cells performed in the transmitt
16、er and receiver are not part of this interface standard but are given for information in annex A. 2 Normative references This ETS incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the public
17、ations are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this ETC only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. Il ITU-T Recommendation G.7
18、02 (1988): “Digital hierarchy bit rates“. 31 41 51 ETS 300 167: “Transmission and Multiplexing (TM); Functional characteristics of 2 048 kbit/s interfaces“. ETS 300 147 (1 995): “Transmission and Multiplexing (TM); Synchronous digital hierarchy ; Multiplexing st ruct Ure“. ITU-T Recommendation G.831
19、 (1 996): “Management capabilities of transport networks based on the Synchronous Digital Hierarchy (SDH)“. ITU-T Recommendation T.50 (1992): “Information technology - 7-bit coded character set for information interchange“. ITU-T Recommendation G.707 (1995): “Synchronous Digital Hierarchy (SDH) bit
20、rat es“ . 3 Definitions and abbreviations 3.1 Definitions For the purposes of this ETS, the following definitions apply: idle cell: A cell which is inserted and extracted by the adaptation function between the ATM virtual path layer network and the PDH path layer network in order to adapt the cell f
21、low rate to the available payload capacity of the PDH path used. valid cell: A cell whose header is declared by the cell Header Error Control (HEC) process to be free of errors. NOTE: The order of transmission of information in all diagrams in this ETS is first from left to right and then top to bot
22、tom. Within each byte the most significant bit is transmitted first. The most significant bit (bit 1) is illustrated at the left of all diagrams. Previous page is blank STD-ETSI ETS 300 337-ENGL 1997 3400855 0198897 T73 Page 8 ETS 300 337: June 1997 3.2 Abbreviations For the purposes of this ETS, th
23、e following abbreviations apply: ATM CRC EM FA GC HEC I EC MSB MA NR OAM PDH RDI REI SDH SSM TR TS TT I TU TUG-n BIP-8 TU-x Asynchronous Transfer Mode Bit Interleaved Parity - 8 Cyclic Redundancy Check Error Monitoring Frame Alignment General purpose Communication Header Error Control Incoming Error
24、 Count Most Significant Bit Maintenance and Adaptation Network operatoR Operations, Administration and Maintenance Plesiochronous Digital Hierarchy Remote Defect Indication Remote Error Indication Synchronous Digital Hierarchy Synchronization Status Message TRail trace Time Slot Trail Trace Identifi
25、er Tributary Unit Tributary Unit Group of level n Tributary Unit - x 4 Frame structure at 2 048 kbis 4.1 Basic frame structure The basic frame structure at 2 048 kbit/s as described in ETS 300 167 2 shall be used. This comprises a generic path overhead, a signalling channel and a generic payload cap
26、acity of 1 920 kbit/s. 4.2 Support of ATM cells in 2 048 kbitls Valid or idle cells are supported in bits 9 to 128 and bits 137 to 256 of the 2 048 kbitls frame with the octet structure of the cells aligned with the octet structure of the frame (see figure 1). Bits 129 to 136 correspond to Time Slot
27、 16 (TS 16) in an octet structured frame and are reserved for future use. Valid or idle cells occupy the whole of the payload and a cell can cross a 125 ps frame boundary. The ATM cell payload is scrambled using a self-synchronizing scrambler with the generator polynomial x 43 + 1. Cell payload fiel
28、d scrambling is required to provide security against false cell delineation and to prevent the cell payload replicating the 2 048 kbitls frame alignment word. TSO path overhead bits 1-8 TS 16 bits 129-136 9 bit num bers 128 137 bit numbers 256 Figure 1: Frame structure at 2 048 kbitls STD-ETSI ETS 3
29、00 337-ENGL 1777 3q00855 0338878 72T Page 9 ETC 300 337: June 1997 5 Frame structure at 34 368 kbis 5.1 Basic frame structure This frame structure is intended to be used in a generic way. When implementing this frame structure, care should be taken to ensure that the performance of the frame alignme
30、nt mechanism is not compromised by the payload content. 5.1.1 General The basic frame structure at 34 368 kbit/s comprises 7 octets of generic path overhead and 530 octets of payload capacity per 125 ps as shown in figure 2. 1 I FA1 - 530 octets payload 9 r O w Figure 2: Frame structure at 34 368 kb
31、iVs STD*ETSI ETS 300 337-ENGL 1797 3400855 0398879 8bh Page 10 ETS 300 337: June 1997 FA1 11 11 0 11 0 O O 10 10 5.1.2 Path overhead 0 0 FA2 EM TR MA NR GC M FI = M ultifram e Indicator SSM = Synchronization Status Message - BIP-8 TRAIL TRACE RDI REI Payload Type MFI SSM NR GC Figure 3: Path overhea
32、d at 34 368 kbiVs A 1 lA2: EM: TR: Frame Alignment signal, this has the same pattern as defined in clause 7 of ETS 300 147 3. Error Monitoring, BIP-8. One byte is allocated for path error monitoring. This function shall be a BIP-8 code using even parity. The path BIP-8 is calculated over all bits of
33、 the previous 125 ps frame. The computed BIP-8 is placed in the EM byte of the current 125 ps frame. Trail trace. This byte is used to transmit repetitively a trail access point identifier so that a trail receiving terminal can verify its continued connection to the intended transmitter. The trail a
34、ccess point identifier shall use the access point identifier format as defined in section 3 of ITU-T Recommendation G.831 4. Trail access point Identifier format: A 16-byte frame is defined for the transmission of the access point identifier. The first byte of the string is a frame start marker and
35、includes the result of a CRC-7 calculation over the previous frame. The following 15 bytes are used for the transport of 15 ITU-T Recommendation T.50 5 characters required for the access point identifier. The 16-byte frame is given below: 1 c, cccccc 7: frame start marker; oxxxxxxx: byte 2; oxxxxxxx
36、: byte 16; oxxxxxxx: ITU-T Recommendation T.50 5 character; c, cccccc 7: result of the CRC-7 calculation over the previous frame. STD-ETSI ETS 300 337-ENGL 1997 = 3400855 0198900 308 H Page 11 ETC 300 337: June 1997 The description of the CRC-7 calculation is given below. Multiplication/division pro
37、cess A particular CRC-7 word is the remainder after multiplication by x and then division (modulo 2) by the generator polynomial x7 + x3 + 1, of the polynomial representation of the previous Trail Trace Identifier (TTI) multiframe. When representing the contents of the block as a polynomial, the fir
38、st bit in the block, (.e. byte 1, bit 1) should be taken as being the most significant bit. Similarly, C is defined to be the most significant bit of the remainder and C, to be the least significant bit of the remainder. Encoding procedure Contrary to e.g. the CRC-4 procedure in 2 Mbit/s signals, th
39、e CRC-7 word is static because the data is static (the TTI represents the source address). This means that the CRC-7 checksum can be calculated a priori over the TTI multiframe. For consistency with existing recommendations the CRC-7 checksum is to be calculated over the previous multiframe. In theo
40、ry this means that the 16-byte string that is loaded in a device for repetition transmission should have the checksum as the last byte although in practice it does not really matter because the TTI is static. The encoding procedure is as follows: a) the CRC-7 bits in the TTI are replaced by binary “
41、0“s; b) the TTI is then acted upon by the multiplication/division process referred to above; c) the remainder resulting from the multiplicatiorddivision process is inserted into the CRC-7 location. The CRC-7 bits generated do not affect the result of the multiplication/division process because, as i
42、ndicated in a) above, the CRC-7 bit positions are initially set to “O“ during the multiplicatiorddivision process. Decoding procedure The decoding procedure is as follows: a) a received TTI is acted upon by the multiplication/division process referred to above after having its CRC-7 bits extracted a
43、nd replaced by “0“s; b) the remainder resulting from the division process is then compared on a bit-by-bit basis with the CRC-7 bits received; c) if the remainder calculated in the decoder exactly corresponds to the CRC-7 bits received, it is assumed that the checked TTI is error free. STDmETSI ETS
44、300 337-ENGL 1997 m 3400855 OL989OL 24l m Page 12 ETS 300 337: June 1997 MA: Maintenance and Adaptation byte: bit 1 bit 2 bits 3-5 bits 6-7 bit 8 RDI (Remote Defect Indication) REI (Remote Error Indication), this bit is set to “1“ and sent back to the remote Path termination if one or more errors we
45、re detected by the BIP-8, and is otherwise set to zero. Payload type: Code Signal O00 Unequipped; O0 1 Equipped, non-specific; o1 o ATM; o1 1 SDH Tu-12; M ult iframe indicator. This bit is used in a four frame multiframe. The phase of the multiframe is determined by the value of MA bits 6-7, accordi
46、ng 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 a Synchronization Status Message (SSM). The coding of the SSM is given in Table 5 of ITU-T Recommendation G.707 6. When interworking with “old“ equipment whic
47、h used bit 8 as a timing 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 Ref
48、erence Clock, and is otherwise set to “1“. N R: Network operator byte. This byte is allocated for maintenance purposes specific to individual network operators. Its transparency from path termination to path termination is not guaranteed in cases where the path traverses operator domains. For tandem
49、 connection maintenance, the byte is used in accordance with annex D of ITU-T Recommendation G.707 6. GC: General purpose Communications channel (e.g. to provide datahoice channel connection for maintenance purposes). vb 5.2 Support of ATM cells in 34 368 kbis The octet structure of the valid or idle cells is aligned with the octet structure of the payload area. Valid or idle cells occupy the whole of the payload and a cell can cross a 125 ps frame boundary. The ATM cell payload is scrambled using a self-synchronizing scrambler with the generator polyno
