SIST ETS 300 821 E1:2003

• Abstract:

  This ETS is an endorsement of the ITU-T recommendation I.frame, which specifies a function that allows data communication applications utilizing protocol stacks which contain HDLC procedures also to be deployed in a B-ISDN environment.

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• 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 300 821 ed.1 (1998-09) - Broadband Integrated Services Digital Network (B-ISDN); ATM Adaptation Layer (AAL); Support of the High Level Data Link Control (HDLC) core service by AAL type 5 [ITU-T Recommendation I.365.4 (1996)]

SIST ETS 300 821 E1:2003 is the Slovenian standard published by SIST for Broadband Integrated Services Digital Network (B-ISDN). It reproduces and endorses ITU-T Recommendation I.365.4, and it specifies how High Level Data Link Control (HDLC) core service is supported by ATM Adaptation Layer type 5 (AAL type 5) so HDLC-based protocol stacks can be deployed in a B-ISDN environment.

What does SIST ETS 300 821 E1:2003 specify?

SIST ETS 300 821 E1:2003 specifies a Service Specific Convergence Sublayer for HDLC applications, called DL-FRAME SSCS. In practice, it defines the mapping that lets HDLC framing be carried through AAL type 5 instead of using a native HDLC framing sublayer.

The standard applies to equipment attached to a B-ISDN network when protocol stacks developed for an HDLC-based environment are to be used there. It is organized into a foreword, clauses 1 to 6, and history:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Definitions and abbreviations
• Clause 4 - General Description
• Clause 5 - Functions of the DL-FRAME SSCS
• Clause 6 - Specification of the DL-FRAME SSCS

What are the key requirements of SIST ETS 300 821 E1:2003?

SIST ETS 300 821 E1:2003 defines the DL-FRAME SSCS as a framing and bit error detection service for HDLC control procedures. The key practical point is that the HDLC Address, Control, and Information fields are carried as data through AAL type 5, while HDLC framing functions are handled by the AAL type 5 service.

Service model and data path

Clause 5 maps DL-FRAME primitives onto a subset of the AAL type 5 CPCS service. The HDLC frame structure is transported as a CPCS-SDU. For implementers, this means the HDLC control procedure sublayer still builds and interprets the protocol data, but the framing transport is delegated to AAL type 5.

DL-FRAME service behavior

Clause 6.1 says the DL-FRAME SSCS preserves DL-FRAME-SDU sequence integrity. It also defines only a request and an indication primitive, both carrying Interface Data. This matters because the interface is intentionally narrow and oriented to message transfer, not a full HDLC framing stack.

AAL type 5 service use

Clause 6.2 states that the AAL type 5 CPCS service is taken from ITU-T Recommendation I.363.5, and that if there is any difference, I.363.5 is definitive. The same clause notes that the message-mode only, and the corrupted data delivery option is not used. For an implementer, that limits the supported operating mode and simplifies the receiver behavior.

PDU and parameter mapping

Clause 6.3 states that the AAL type 5 CPCS SDU is equivalent to the Interface Data parameter of DL-FRAME-UNITDATA, with no further Protocol Control Information added. Clause 6.4 sets the transmitter mapping: CPCS-LP, CPCS-CI, and CPCS-UU are set to 0, with CPCS-LP also allowed to be set to 1 by Layer Management decision. Clause 6.5 sets the receiver mapping: the Interface Data is passed up, while CPCS-LP, CPCS-CI, and CPCS-UU are ignored.

Length and integrity limits

Clause 6.1 says the Interface Data length is an integral number of octets and that its maximum length depends on AAL type 5 CPCS capability. It also notes that although the absolute maximum CPCS-PDU length is 65 535 octets, the practical maximum depends on ATM connection error characteristics. This is important when sizing payloads and planning interoperability.

Layer Management

Clause 6.6 says there are no defined Layer Management interactions, while reporting CPCS-CI values is left for further study. In practice, this means congestion-related handling is not standardized beyond the basic mapping rules.

What terms does SIST ETS 300 821 E1:2003 define?

SIST ETS 300 821 E1:2003 uses several terms in a specific way:

• HDLC framing - the flag and abort sequences, zero-bit insertion, and Frame Checking Sequence (FCS) functions of HDLC.
• DL-FRAME primitives - the service primitives used to access the HDLC framing sublayer.
• Service Specific Convergence Sublayer (SSCS) - the sublayer that adapts a service to a particular application, here HDLC applications.
• Common Part Convergence Sublayer (CPCS) - the AAL type 5 sublayer used for the data transfer mapping.
• CPCS-SDU - the data unit carried by the CPCS; in this standard it matches the DL-FRAME Interface Data.
• Frame Checking Sequence (FCS) - the HDLC error-detection field included in HDLC framing.
• PDU - Protocol Data Unit, the formatted unit exchanged between protocol layers.

Who uses SIST ETS 300 821 E1:2003?

SIST ETS 300 821 E1:2003 is used by designers of B-ISDN and ATM equipment, especially when existing HDLC-based protocol stacks must be carried over AAL type 5. It is relevant to network equipment vendors, telecom integrators, and engineers working with X.25-based layer 2 systems, because it defines how to preserve HDLC service behavior across the B-ISDN boundary.

Which standards are used with SIST ETS 300 821 E1:2003?

SIST ETS 300 821 E1:2003 relies on these referenced standards:

• ITU-T Recommendation I.363.5 - defines AAL type 5 CPCS, which is the definitive service definition used by this ETS.
• ITU-T Recommendation X.25 - provides the HDLC-based packet-mode environment mentioned in the scope.
• ITU-T Recommendation X.200 - supplies the OSI layering concepts used in the definitions.
• ITU-T Recommendation X.210 - supplies the service primitive conventions used for the DL-FRAME interface.
• ITU-T Recommendation I.365.4 - is the ITU-T recommendation reproduced and endorsed by this ETS.

What does the SIST ETS 300 821 E1:2003 document contain?

SIST ETS 300 821 E1:2003 contains the service definition, the primitive tables, and the transmitter and receiver mapping rules needed to implement the HDLC-to-AAL type 5 adaptation. It includes a general description of the environment, then the DL-FRAME SSCS service description and the CPCS service summary.

The document also includes Figure 1 showing the deployment environment for HDLC applications and Figure 2 showing the relationship between DL-FRAME primitives and AAL type 5 CPCS signals. Table 1 summarizes DL-FRAME service primitives and parameters, and Table 2 summarizes the AAL type 5 CPCS primitives and parameters.

SLOVENSKI STANDARD
01-december-2003
âLURNRSDVRYQRGLJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL%,6'1±3ULODJRGLOQD
SODVW$70$$/±3RGSRUDMHGUQLVWRULWYLNUPLOMHQMDSRYH]DYHYLVRNRQLYRMVNLK
SRGDWNRY]$$/WLSD$$/>SULSRURþLOR,787,@
Broadband Integrated Services Digital Network (B-ISDN); ATM Adaptation Layer (AAL);
Support of the High Level Data Link Control (HDLC) core service by AAL type 5 [ITU-T
Recommendation I.365.4 (1996)]
Ta slovenski standard je istoveten z: ETS 300 821 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 821
TELECOMMUNICATION September 1998
STANDARD
Source: NA Reference: DE/NA-052627
ICS: 33.020
Key words: ATM, B-ISDN, layer 2
Broadband Integrated Services Digital Network (B-ISDN);
ATM Adaptation Layer (AAL);
Support of the High Level Data Link Control (HDLC)
core service by AAL type 5 (AAL5)
[ITU-T Recommendation I.365.4 (1996)]
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
Internet: [e-mail] - http://www.etsi.fr - http://www.etsi.org
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 1998. All rights reserved.

Page 2
ETS 300 821: September 1998
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 Standards Making Support Dept." at the address shown on the title page.

Page 3
ETS 300 821: September 1998
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .7
3.1 Definitions .7
3.2 Abbreviations .8
4 General Description.8
5 Functions of the DL-FRAME SSCS.8
6 Specification of the DL-FRAME SSCS.9
6.1 The service of the DL-FRAME SSCS .9
6.2 The CPCS service of the AAL type 5.9
6.3 PDU format .10
6.4 Mapping the DL-FRAME primitive into the AAL type 5 CPCS signal (transmitter) .10
6.5 Mapping the AAL type 5 CPCS signal into the DL-FRAME primitive (receiver) .11
6.6 Layer Management.11
History.12

Page 4
ETS 300 821: September 1998
Blank page
Page 5
ETS 300 821: September 1998
Foreword
This European Telecommunication Standard (ETS) has been produced by the Network Aspects (NA)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS reproduces and endorses the ITU-T Recommendation I.365.4 [5].
Transposition dates
Date of adoption of this ETS: 18 September 1998
Date of latest announcement of this ETS (doa): 31 December 1998
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 June 1999
Date of withdrawal of any conflicting National Standard (dow): 30 June 1999

Page 6
ETS 300 821: September 1998
Blank page
Page 7
ETS 300 821: September 1998
1 Scope
This European Telecommunication Standard (ETS) specifies a function that allows data communication
applications utilizing protocol stacks which include High Level Data Link Control (HDLC) procedures
(ITU-T Recommendation X.25, [2]) also to be deployed in a Broadband Integrated Services Digital
Network (B-ISDN) environment.
The required mapping function specified in this ETS is called "Service Specific Convergence Sublayer for
HDLC Applications".
This ETS makes use of the fact that the functionality of the HDLC framing, i.e., the flag and abort
sequences, the zero-bit insertion, and the Frame Checking Sequence (FCS) can be interpreted as a
subset of the services offered by the ATM Adaptation Layer type 5 (AAL 5) as specified in
ITU-T Recommendation I.363.5 [1].
This ETS is applicable to equipment to be attached to a B-ISDN network when protocol stacks developed
for an HDLC-based environment are to be deployed.
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 I.363.5: "B-ISDN ATM Adaptation Layer specification:
Type 5 AAL".
[2] ITU-T Recommendation X.25: "Interface between Data Terminal Equipment
(DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in
the packet mode and connected to public data networks by dedicated circuit".
[3] ITU-T Recommendation X.200: "Information technology; Open Systems
Interconnection; Basic reference model: The basic model".
[4] ITU-T Recommendation X.210: "Information technology; Open systems
interconnection; Basic Reference Model: Co
...