SIST ETS 300 337 E2:2003

• Abstract:

  Maintenance of ETS 300 337 (de/tm-03007)

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.040.20 - Transmission systems
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 337 ed.2 (1997-06) - Transmission and Multiplexing (TM); Generic frame structures for the transport of various signals (including Asynchronous 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 kbit/s and 139 264 kbit/s

SIST ETS 300 337 E2:2003 is the SIST adoption of ETS 300 337 Edition 2 from ETSI. It specifies generic frame structures for transporting various signals, including Asynchronous 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 kbit/s and 139 264 kbit/s. Engineers, equipment vendors, operators and test labs use it to define and check PDH frame formats, payload mapping and conformance at those rates.

What does SIST ETS 300 337 E2:2003 specify?

SIST ETS 300 337 E2:2003 specifies the frame structures used to carry traffic at three PDH bit rates and how those frames can also transport ATM cells and SDH-related payloads. It is an interface-focused standard: it tells implementers how the frame is arranged, how overhead is used, and how payload types are identified.

The document is organized into seven clauses and two annexes:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Definitions and abbreviations
• Clause 4 - Frame structure at 2 048 kbit/s
• Clause 5 - Frame structure at 34 368 kbit/s
• Clause 6 - Frame structure at 139 264 kbit/s
• Clause 7 - Conformance testing

Annex	What it covers
Annex A	Functions specific to the support of ATM cells
Annex B	Bibliography

In practice, this structure helps a reader find the rate-specific framing rules quickly and separates the main interface rules from ATM-specific implementation notes.

What are the key requirements of SIST ETS 300 337 E2:2003?

The standard’s main requirements are the frame layouts at 2 048 kbit/s, 34 368 kbit/s and 139 264 kbit/s, plus the way each frame identifies payload type, error monitoring and trail information. It also defines how ATM cells are carried and how SDH payloads are arranged at the higher rates.

2 048 kbit/s frame structure

Clause 4 says the 2 048 kbit/s frame uses the basic frame structure defined in ETS 300 167, including generic path overhead, a signalling channel and a 1 920 kbit/s payload capacity. For ATM use, valid or idle cells occupy the payload area, can cross the 125 μs frame boundary, and use octet alignment with the frame.

For the reader, this means a 2 Mbit/s implementation must preserve the ETS 300 167 framing and must handle ATM cells without forcing them to stay inside one frame.

34 368 kbit/s frame structure

Clause 5 defines a generic frame made of 7 octets of path overhead and 530 octets of payload per 125 μs. The standard highlights that payload content should not disturb frame alignment performance, so payload design matters to reliable reception.

The path overhead carries frame alignment, error monitoring by BIP-8, trail trace using a trail access point identifier, maintenance and adaptation information, a network operator byte and a general purpose communications channel. In practice, this gives the equipment a way to verify the trail, report errors back to the far end, and carry operator-specific maintenance data.

Clause 5 also defines support for ATM cells and for 14 SDH TU-12s. The TU-12 mapping uses a fixed interleaving structure and a multiframe indicator, so implementers must keep the pointer phase relationship and multiframe timing intact.

139 264 kbit/s frame structure

Clause 6 defines a larger frame with 16 octets of generic path overhead and 2 160 octets of payload per 125 μs. The standard states that the first 9 octets of overhead are defined and the remaining 7 octets, if unused, should be set to 00 HEX.

The overhead includes frame alignment, BIP-8 error monitoring, trail trace, maintenance and adaptation, and automatic protection switching bytes. The payload type field identifies unequipped, equipped non-specific, ATM, and SDH element mappings, so the receiver knows what kind of traffic is being transported.

Clause 6 supports ATM cells in the same way as the lower-rate ATM mapping: valid or idle cells fill the payload, may cross a frame boundary, and use payload scrambling to avoid false cell delineation. It also supports SDH element mappings in two arrangements - 20 x TUG-2, or 2 x TUG-3 and 5 x TUG-2 - which matters when the system carries structured SDH traffic rather than ATM cells.

Conformance testing

Clause 7 says conformance testing is performed on physical interfaces and is aimed at the functional blocks inside a network element. For buyers and quality teams, that means compliance is checked at the equipment function level, not only by paperwork.

What terms does SIST ETS 300 337 E2:2003 define?

SIST ETS 300 337 E2:2003 defines several terms and abbreviations that are central to the frame and payload rules.

• idle cell - A cell inserted and removed by the adaptation function so the ATM cell rate matches the available PDH payload capacity.
• valid cell - A cell whose header has passed the Header Error Control (HEC) check and is treated as error-free.
• Header Error Control (HEC) - The header protection method used to detect header errors and support ATM cell handling.
• BIP-8 - Bit Interleaved Parity - 8, the even-parity error monitoring method used on the path overhead.
• Synchronization Status Message (SSM) - The four-bit message carried through the multiframe-related bits to convey synchronization status.
• Trail Trace Identifier (TTI) - The identifier sent repeatedly so a receiving terminal can confirm it is still connected to the intended source.
• Tributary Unit (TU) / Tributary Unit Group of level n (TUG-n) - SDH payload structures used in the 34 368 kbit/s and 139 264 kbit/s SDH element mappings.

Who uses SIST ETS 300 337 E2:2003?

SIST ETS 300 337 E2:2003 is used by transmission and multiplexing engineers who design PDH interfaces, ATM transport and SDH mappings. It is also used by equipment manufacturers implementing frame alignment, overhead bytes, pointer handling and payload mapping.

Network operators use it when they need consistent maintenance indicators, trail trace handling and operator-byte behavior across equipment. Test laboratories and conformance teams use it to build physical-interface tests for functional blocks in network elements. Quality managers and buyers use it to confirm that a product supports the right frame structure and payload type at the required bit rate.

What changed in SIST ETS 300 337 E2:2003 from the previous edition?

SIST ETS 300 337 E2:2003 is the second edition of ETS 300 337 and replaces the first edition.

Which standards are used with SIST ETS 300 337 E2:2003?

The standard relies on several normative references that supply the underlying bit rates, framing patterns and maintenance formats:

• ITU-T Recommendation G.702 - defines the digital hierarchy bit rates used by the frame structures.
• ETS 300 167 - provides the 2 048 kbit/s functional frame structure used in Clause 4.
• ETS 300 147 - provides the SDH multiplexing structure and the frame alignment pattern used for the higher-rate frames.
• ITU-T Recommendation G.831 - defines the access point identifier format used for trail trace.
• ITU-T Recommendation T.50 - defines the 7-bit coded character set used in the identifier.
• ITU-T Recommendation G.707 - supplies SDH bit-rate information, SSM coding and tandem connection maintenance guidance.

Annex A also points to ITU-T Recommendation I.432 for ATM cell rate adaptation, HEC generation, delineation and header verification. Annex B lists ITU-T Recommendations G.804 and G.832 as background for ATM cell mapping and SDH transport over PDH networks.

What does the SIST ETS 300 337 E2:2003 document contain?

The document contains detailed bit and octet layouts for the 2 048 kbit/s, 34 368 kbit/s and 139 264 kbit/s frames, shown in figures for each rate. It also contains the multiframe coding rules in tables for TU-12 mapping and TU multiframe indication.

For implementation work, the most useful parts are the path overhead descriptions, the CRC-7 procedure for trail trace, the payload type fields, and the SDH mapping arrangements. Annex A gives the ATM support functions needed at the transmitter and receiver, while Clause 7 gives the basis for conformance testing using physical interfaces.

SLOVENSKI STANDARD
01-december-2003
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Transmission and Multiplexing (TM); Generic frame structures for the transport of various
signals (including Asynchronous 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 kbit/s and 139 264 kbit/s
Ta slovenski standard je istoveten z: ETS 300 337 Edition 2
ICS:
33.040.20 Prenosni sistem Transmission systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 337
TELECOMMUNICATION June 1997
STANDARD 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 Asynchronous 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 kbit/s and 139 264 kbit/s
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail]
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

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ETS 300 337: June 1997
Whilst every care has been taken in the preparation 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.

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ETS 300 337: June 1997
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .7
3.1 Definitions .7
3.2 Abbreviations .8
4 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
5 Frame structure at 34 368 kbit/s .9
5.1 Basic frame structure.9
5.1.1 General.9
5.1.2 Path overhead .10
5.2 Support of ATM cells in 34 368 kbit/s .12
5.3 Support of 14 SDH TU-12s in 34 368 kbit/s.12
5.3.1 Coding of multiframe indicator for TU multiframe indication .13
6 Frame structure at 139 264 kbit/s .14
6.1 Basic frame structure.14
6.1.1 General.14
6.1.2 Path overhead .15
6.2 Support of ATM cells in 139 264 kbit/s .17
6.3 Support of SDH elements in 139 264 kbit/s.18
6.3.1 Coding of multiframe indicator for TU multiframe indication .18
6.3.2 Support of 20 x TUG-2 .18
6.3.3 Support of 2 x TUG-3 and 5 x TUG-2 .18
7 Conformance testing .20
Annex A (informative): Functions specific to the support of ATM cells.21
A.1 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): Bibliography.22
History.23

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ETS 300 337: June 1997
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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 Telecommunications
Standards Institute (ETSI).
This ETS specifies generic frame structures for the transport of various signals at the
ITU-T Recommendation G.702 [1] hierarchical rates of 2 048 kbit/s, 34 368 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 also covered in this ETS.
This ETS takes into account the recommendations given in ITU-T Recommendation G.804 (annex B.2)
and G.832 (annex B.3) - see annex B (Bibliography) for details.
Transposition dates
Date of adoption: 7 March 1997
Date of latest announcement of this ETS (doa): 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

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ETS 300 337: June 1997
Blank page
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ETS 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 [1] hierarchical rates of 2 048 kbit/s,
34 368 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 transmitter
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 publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ITU-T Recommendation G.702 (1988): "Digital hierarchy bit rates".
[2] ETS 300 167: "Transmission and Multiplexing (TM); Functional characteristics of
2 048 kbit/s interfaces".
[3] ETS 300 147 (1995): "Transmission and Multiplexing (TM); Synchronous digital
hierarchy; Multiplexing structure".
[4] ITU-T Recommendation G.831 (1996): "Management capabilities of transport
networks based on the Synchronous Digital Hierarchy (SDH)".
[5] ITU-T Recommendation T.50 (1992): "Information technology - 7-bit coded
character set for information interchange".
[6] ITU-T Recommendation G.707 (1995): "Synchronous Digital Hierarchy (SDH) bit
rates".
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 flow 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 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.

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ETS 300 337: June 1997
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
ATM Asynchronous Transfer Mode
BIP-8 Bit Interleaved Parity - 8
CRC Cyclic Redundancy Check
EM Error Monitoring
FA Frame Alignment
GC General purpose Communication
HEC Header Error Control
IEC Incoming Error Count
MSB Most Significant Bit
MA Maintenance and Adaptation
NR Network operatoR
OAM Operations, Administration and Maintenance
PDH Plesiochronous Digital Hierarchy
RDI Remote Defect Indication
REI Remote Error Indication
SDH Synchronous Digital Hierarchy
SSM Synchronization Status Message
TR TRail trace
TS Time Slot
TTI Trail Trace Identifier
TU Tributary Unit
TUG-n Tributary Unit Group of level n
TU-x Tributary Unit - x
4 Frame structure at 2 048 kbit/s
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 capacity of 1 920 kbit/s.
4.2 Support of ATM cells in 2 048 kbit/s
Valid or idle cells are supported in bits 9 to 128 and bits 137 to 256 of the 2 048 kbit/s 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 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 μs frame boundary. The ATM cell
payload is scrambled using a self-synchronizing scrambler with the generator polynomial x + 1. Cell
payload field scrambling is required to provide security against false cell delineation and to prevent the cell
payload replicating the 2 048 kbit/s frame alignment word.
TS0 TS 16
bits 1-8 bits 129-136
path overhead reserved for signalling
9 bit num bers 128 137 bit num bers 256
Figure 1: Frame structure at 2 048 kbit/s

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ETS 300 337: June 1997
5 Frame structure at 34 368 kbit/s
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 alignment 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 μs as shown in figure 2.
59 columns
FA1 FA2
EM
TR
MA
530 octets
r
payload
o
NR
w
s
GC
Figure 2: Frame structure at 34 368 kbit/s

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ETS 300 337: June 1997
5.1.2 Path overhead
The values and allocation of the path overhead are shown in figure 3 and are described below.
1 1 1 0110 0 0 1 0 1 0 0 0
FA1 1 FA2
BIP-8
EM
TRAIL TRACE
TR
MA MFI SSM
Payload T .ype
RDI
REI
NR
NR
GC
GC
MFI = Multiframe Indicator
SSM = Synchronization Status Message
Figure 3: Path overhead at 34 368 kbit/s
FA1/FA2: Frame Alignment signal, this has the same pattern as defined in clause 7 of
ETS 300 147 [3].
EM: 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 the previous 125 μs frame. The computed BIP-8 is placed in the
EM byte of the current 125 μs frame.
TR: 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 access 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 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:
1C CCCCCC : frame start marker;
1 7
0XXXXXXX: byte 2;
0XXXXXXX: byte 16;
0XXXXXXX: ITU-T Recommendation T.50 [5] character;
C CCCCCC : result of the CRC-7 calculation over the previous frame.
1 7
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ETS 300 337: June 1997
The description of the CRC-7 calculation is given below.
Multiplication/division process
A particular CRC-7 word is the remainder after multiplication by x and then division (modulo 2) by the
7 3
generator polynomial x + x + 1, of the polynomial representation of the previous Trail Trace Identifier
(TTI) multiframe.
When representing the contents of the block as a polynomial, the first bit in the block, (i.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, the 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
...