ETSI ETS 300 354 ed.1 (1995-08)

Broadband Integrated Services Digital Network (B-ISDN); B-ISDN Protocol Reference Model (PRM)

DE/NA-052729

Širokopasovno digitalno omrežje z integriranimi storitvami (B-ISDN) – Referenčni model protokola (PRM) v B-ISDN

General Information

• Status: Published
• Publication Date: 08-Aug-1995
• Technical Committee: NA 5 - Broadband Networks
• Current Stage: 12 - Completion
• Due Date: 25-Aug-1995
• Completion Date: 09-Aug-1995
• Ref Project: SIST ETS 300 354 E1:2003 - Broadband Integrated Services Digital Network (B-ISDN); B-ISDN Protocol Reference Model (PRM)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 354 E1:2003
01-december-2003
âLURNRSDVRYQRGLJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL%,6'1±5HIHUHQþQL
PRGHOSURWRNROD350Y%,6'1
Broadband Integrated Services Digital Network (B-ISDN); B-ISDN Protocol Reference
Model (PRM)
Ta slovenski standard je istoveten z: ETS 300 354 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
SIST ETS 300 354 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 354 E1:2003

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SIST ETS 300 354 E1:2003
EUROPEAN ETS 300 354
TELECOMMUNICATION August 1995
STANDARD
Source: ETSI TC-NA Reference: DE/NA-052729
ICS: 33.040
Broadband, ISDN, PRM
Key words:
Broadband Integrated Services Digital Network (B-ISDN);
B-ISDN Protocol Reference Model (PRM)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - [e-mail]
X.400: Internet:
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 1995. All rights reserved.
New presentation - see History box

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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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Contents
Foreword .5
Introduction.5
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .7
3.1 Definitions .7
3.2 Abbreviations .8
4 The B-ISDN PRM.9
5 Description of the planes.10
5.1 User plane.10
5.2 Control plane.10
5.3 Management plane .10
5.3.1 Plane management function .10
5.3.2 Layer management functions.10
6 Functions of the individual layers of the B-ISDN PRM .10
6.1 Physical layer.11
6.1.1 Physical medium sublayer functions .11
6.1.1.1 Physical medium.11
6.1.1.2 Bit timing.11
6.1.2 TC sublayer functions.11
6.1.2.1 Transmission frame generation and recovery .11
6.1.2.2 Transmission frame adaptation .11
6.1.2.3 Cell delineation .11
6.1.2.4 HEC sequence generation and cell header verification.11
6.1.2.5 Cell rate decoupling.12
6.1.3 Physical layer model.12
6.1.4 Physical layer primitives .14
6.1.4.1 Primitives between the PL and the ATM layer.15
6.1.4.2 Primitives between the TC sublayer and the PM sublayer .16
6.1.4.3 Primitives between the PL and the PL management.16
6.1.5 OAM related to the PL.17
6.2 ATM layer.17
6.2.1 ATM layer functions.17
6.2.1.1 Cell multiplexing and demultiplexing.17
6.2.1.2 Virtual Path Identifier (VPI) and Virtual Channel Identifier
(VCI) translation.17
6.2.1.3 Cell header generation/extraction.17
6.2.1.4 Generic flow control.17
6.2.2 ATM layer model .17
6.2.3 ATM layer primitives.20
6.2.3.1 Primitives between ATM layer and AAL .20
6.2.3.2 Primitives between the ATM layer and the ATMM.21
6.2.3.2.1 Connection assign/remove primitives.21
6.2.3.2.2 Management data transfer primitives .23
6.2.3.2.3 Error reporting primitives .24
6.2.3.2.4 Other primitives .25
6.2.4 OAM related to the ATM layer.29
6.3 AAL .29
6.4 Higher layers.29

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Annex A (normative): PRM information flow for user plane connection establishment. 30
A.1 Example. 30
A.2 PRM information flow. 30
Annex B (informative): Bibliography . 33
History. 34

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Network Aspects (NA)
Technical Committee of the European Telecommunication Standards Institute (ETSI).
Transposition dates
Date of adoption of this ETS: 28 July 1995
Date of latest announcement of this ETS (doa): 30 November 1995
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 May 1996
Date of withdrawal of any conflicting National Standard (dow): 31 May 1996
Introduction
This ETS is based on the Broadband Integrated Services Digital Network (B-ISDN) Protocol Reference
Model (PRM) as defined in ITU-T Recommendation I.320 [Error! Bookmark not defined.]. The purpose
of this ETS is to take into account the functionalities of B-ISDN, in order to enhance the existing ISDN
PRM. The PRM in this ETS will be referred to as the B-ISDN PRM.
The B-ISDN layered model reflects the principles of layered communication defined in ITU-T
Recommendation X.200 [6].
Open Systems Interconnection (OSI) is a logical architecture and, as such, defines a set of principles
including protocol layering, layer service definition, service primitives, modularity and independence. In
general, these principles have been followed in the definition of the B-ISDN PRM. However, the principle
of layer independence has not been fully applied in this B-ISDN PRM.
The OSI reference model has seven layers, each with specific functions and offering defined services to
the layer above and utilizing services of the layer below. This logical architecture seems applicable also to
the B-ISDN.

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1 Scope
This European Telecommunication Standard (ETS) addresses the Broadband Integrated Services Digital
Network (B-ISDN) Protocol Reference Model (PRM) and its applications. It is an extension of the CCITT
Recommendation I.321 [Error! Bookmark not defined.], including also a description of the Physical
Layer (PL) and Asynchronous Transfer Mode (ATM) layer internal structure, as well as the primitives
between these two layers, and towards the Layer Management Entities (LME), and the primitives between
the ATM layer and the ATM Adaptation Layer (AAL).
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.320 (1993): "ISDN protocol reference model".
[2] CCITT Recommendation I.321 (1991): "B-ISDN protocol reference model and
its applications".
[3] ITU-T Recommendation I.361 (1993): "B-ISDN ATM layer specification".
[4] ITU-T Recommendation I.432 (1993): "B-ISDN user-network interface - Physical
layer specification".
[5] ITU-T Recommendation I.610 (1993): "B-ISDN operation and maintenance
principles and functions".
[6] ITU-T Recommendation X.200 (1994): "Information technology - Open systems
interconnection - Basic reference model: The basic model".
[7] CCITT Recommendation Q.940 (1988): "ISDN user-network interface protocol
for management - General aspects".
[8] CCITT Recommendation G.703 (1991): "Physical/Electrical characteristics of
hierarchical digital interfaces".
3 Definitions and abbreviations
3.1 Definitions
idle cell (physical layer): Cell which is inserted/extracted by the PL in order to adapt the cell flow rate at
the boundary between the ATM layer and the PL to the available payload capacity of the transmission
system used.
valid cell (physical layer): Cell whose header has no errors or has been modified by the cell Header
Error Control (HEC) verification process.
invalid cell (physical layer): Cell whose header has errors and has not been modified by the cell HEC
verification process (discarded at the PL).
assigned cell (ATM layer): Cell which provides a service to an application using the ATM layer service.
unassigned cell (ATM layer): ATM layer cell which is not an assigned cell.
(N)-Service Access Point (SAP): The point at which (N)-services are provided by an (N)-entity to an
(N+1)-entity (ITU-T Recommendation X.200 [6]).
In this ETS the above definition is used for the term SAP. In this ETS, (N) is the PL or the ATM layer.

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3.2 Abbreviations
For the purposes of this ETS the following abbreviations apply:
AAL ATM Adaptation Layer
ATM Asynchronous Transfer Mode
ATMM ATM layer Management
B-ISDN Broadband Integrated Services Digital Network
CE Connection End-point
CEI Connection End-point Identifier
CES Connection End-point Suffix
CLP Cell Loss Priority
CME Connection Management Entity
CRC Cyclic Redundancy Check
CS Convergence Sublayer
DSS Distributed Sample Scrambler
EBCN Explicit Backward Congestion Notification
EC Error Correction
ED Error Detection
EFCN Explicit Forward Congestion Notification
GFC Generic Flow Control
GME Global Management Entity
HEC Header Error Control
LE Layer Entity
LI Link Identifier
LME Layer Management Entity
NNI Network Node Interface
NPC Network Parameter Control
OAM Operation and Maintenance
OSI Open Systems Interconnection
PCI Protocol Control Information
PDH Plesiochronous Digital Hierarchy
PDU Protocol Data Unit
PL Physical Layer
PM Physical Medium
PRM Protocol Reference Model
PT Payload Type
QoS Quality of Service
SAP Service Access Point
SAPI Service Access Point Identifier
SAR Segmentation and Reassembly
SDH Synchronous Digital Hierarchy
SDU Service Data Unit
SLE Sub-Layer Entity
TC Transmission Convergence
UNI User-Network Interface
UPC Usage Parameter Control
VC Virtual Channel
VCC Virtual Channel Connection
VCI Virtual Channel Identifier
VP Virtual Path
VPC Virtual Path Connection
VPI Virtual Path Identifier

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Plane management
Layer management
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4 The B-ISDN PRM
The B-ISDN PRM is shown in figure 1; it is composed of a user plane, a control plane, and a management
plane.
Above the PL, the ATM layer provides for the transport of data for all services. The service provided by
the AAL to the layer above depends on the service class to be supported.
The layer above the AAL in the control plane provides call control and connection control. The management
plane provides network supervision functions. Functional description of the PL, the ATM layer, and the AAL
are given in the following sections. Further study is required on the layers above the AAL.
Control User
plane plane
Higher layers Higher layers
ATM adaptation layer
ATM layer
Physical layer
Figure 1: B-ISDN PRM
Manageme t plane
n

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5 Description of the planes
5.1 User plane
The user plane, with its layered structure, provides for user information transfer, along with associated
controls (e.g. flow control, recovery from errors, etc.).
5.2 Control plane
This plane has a layered structure and performs the call control and connection control functions; it deals
with the signalling necessary to set up, supervise, and release calls and connections.
5.3 Management plane
The management plane provides two types of functions, namely layer management and plane
management functions.
5.3.1 Plane management function
The plane management performs management functions related to a system as a whole and provides co-
ordination between all planes. Plane management has no layered structure.
5.3.2 Layer management functions
Layer management performs management functions (e.g. metasignalling) relating to resources and
parameters related to the protocol entities within the layer. Layer management handles the Operation and
Maintenance (OAM) information flows specific to the layer concerned. Additional details are provided in
CCITT Recommendation Q.940 [7].
6 Functions of the individual layers of the B -ISDN PRM
The functions of each layer, the primitives exchanged between layers, and primitives exchanged between
the layers and the management plane are described below. The information flows described do not imply
a specific physical realization. Figure 2 illustrates the layers of the PRM, and identifies the functions of
the PL, the ATM layer, and the AAL.
H ig h e r
Higher layer functions
la y e rs
L C
Convergence
a S
A
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
y
A
Segmentation and reassembly S
e
L
A
r
R
m
Generic Flow Control
a
A
Cell Header generation/extraction
n
T
Cell VPI/VCI translation
a
M
Cell multiplex and demultiplex
g
e
Cell rate decoupling P l
m
HEC header sequence generation/verification h a
T
e
Cell delineation y y
C
n
Transmission frame adaptation s e
t
Transmission frame generation recovery i r
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
c
Bit timing
P
a
Physical medium
M
l
Figure 2: Functions of the B -ISDN in relation to the PRM

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6.1 Physical layer
The PL consists of two sublayers. The Physical Medium (PM) sublayer includes only PM dependent
functions. The Transmission Convergence (TC) sublayer performs all functions required to transform a
flow of cells into a flow of data units (e.g. bits) which can be transmitted and received over a PM. The
Service Data Unit (SDU) crossing the boundary between the ATM layer and the PL is a valid cell. The
ATM layer is independent of the underlying PL. The data flow inserted in the transmission system payload
is PM independent and self-supported; the PL merges the ATM cell flow with the appropriate information
for cell delineation, according to the cell delineation mechanism described in ITU-T Recommendation
I.432 [4] and carries OAM information relating to this cell flow.
6.1.1 Physical medium sublayer functions
The PM sublayer provides bit transmission capability including bit transfer and bit alignment. It includes
line coding and electrical-optical transformation.
6.1.1.1 Physical medium
The transmission functions are highly dependent on the medium used and are outside the scope of this
ETS.
6.1.1.2 Bit timing
To enable clock recovery, the principal function is the generation and reception of waveforms suitable for
the medium, the insertion and extraction of bit timing information and line coding (if required). The
primitives identified at the border between the PM and TC sublayers are a continuous flow of logical bits or
symbols with this associated timing information.
6.1.2 TC sublayer functions
6.1.2.1 Transmission frame generation and recovery
This function performs the generation and recovery of the transmission frame.
6.1.2.2 Transmission frame adaptation
This function performs the actions which are necessary to structure the cell flow according to the payload
structure of the transmission frame (transmit direction) and to extract this cell flow out of the transmission
frame (receive direction). The transmission frame may be a cell equivalent (i.e. no external envelope is
added to the cell flow), a Synchronous Digital Hierarchy (SDH) envelope, a Plesiochronous Digital
Hierarchy (PDH) envelope, a CCITT Recommendation G.703 [8] envelope, etc.
6.1.2.3 Cell delineation
Cell delineation is the process which allows the receiving side to recover cell boundaries. The HEC field of
the cell header is used to achieve cell delineation according to the self-delineating mechanism defined in
ITU-T Recommendation I.432 [4]. In the transmit direction, the ATM payload part only of the cell stream is
1)
scrambled. Scrambling is used to improve the security and robustness of the HEC cell delineation
mechanism as described in ITU-T Recommendation I.432 [4], § 4.5.1.1. In the receive direction, cell
boundaries are identified and confirmed (using the HEC mechanism) and the cell flow is descrambled.
6.1.2.4 HEC sequence generation and cell header verification
In transmit direction, it calculates the HEC sequence and inserts it in the header. In receive direction, cell
headers are checked for errors and, if possible (see ITU-T Recommendation I.432 [4]), header errors are
corrected. Cell whose headers are determined to be errored and non-correctable are discarded.

1)
Any scrambler specification shall not alter the ATM header structure (as described in ITU-T Recommendation I.361 [3]),
header error control (as described in ITU-T Recommendation I.432 [4], § 4.3), and the cell delineation algorithm (as
described in ITU-T Recommendation I.432 [4], § 4.5.1.1).

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6.1.2.5 Cell rate decoupling
Cell rate decoupling includes insertion and suppression of idle cells, in order to adapt the rate of valid ATM
cells to payload capacity of the transmission system.
6.1.3 Physical layer model
The model of the PL is shown in figure 3. The following assumptions are made:
One PL-SAP is introduced between the PL and the ATM layer.
Associated with the PL-SAP there is one Connection End-point (CE).
The TC Sub-Layer Entity (SLE) exchanges information with the ATM-Layer Entity (LE) across the PL-SAP
by means of service primitives.
The TC-SDU crossing the PL-SAP (see figure 4) is the ATM Protocol Data Unit (ATM-PDU) where the
Protocol Control Information (PCI) does not include the HEC value. This value is inserted at the TC sub-
layer in the relevant field and represents the TC-PCI.
The TC-PDU consists of the complete 53 octets of the TC-SDU with the related TC-PCI.
The presence of a SAP between TC and PM is for further study, however internal primitives, invoke and
signal, between the two sublayers are defined.
The PM-SDU crossing the boundary between the TC sub-layer and the PM sub-layer is a logical bit or
symbol.
The PM-PDU is PM dependent and is associated with waveforms suitable for the medium.
A SAP is identified between the PL and the PL management.
Associated with the PLM-SAP there are different CEs.
In the adopted model a fixed association between a PL management entity and the related CE within the
PLM-SAP is assumed. Each PL-LME is assumed to include a specific set of management functions (e.g.
OAM section and path related functions, Activation/Deactivation, etc.).
A PL-SLE discriminates the related layer management CE by means of preassigned address values (first
2)
four octets of TC-SDU) .
A PL-SLE exchanges information with a PL-LME across the PLM-SAP by means of service primitives.

2)
According to OSI, a (N)-entity has not access to the meaning of a (N)-SDU. The incongruities here are caused by the ATM
related functions allocation in the adopted PRM.

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ATM LAYER ATM LAYER MANAGEMENT
CE P M
PL-SAP
L A
ERROR
A N
HANDLING
N A
TC-SLE
-  CELL_RATE DECOUP
E G
ASSIGN
ENTITY
-  HEC GEN./VER.
E
-  CELL DELINEATION
M
T-PATH
ENTITY
F3
E
F2
N
D-SECTION
ENTITY
PM-SLE
T
-  BIT TIMING
F1
R-SECTION
ENTITY
ACTIV.
ENTITY
PLM-SAP
PHYSICAL LAYER PL MANAGEMENT
Figure 3: Functional model of PL
In figure 3, the following management entities appear:
- assign entity: this associates the layer resources to form the internal link for the transfer of the PL
information;
- T-Path entity (Transmission Path entity): this handles the F3 flow;
- D-Section entity (Digital Section entity): this handles the F2 flow;
- R-Section entity (Repeater Section entity): this handles the F1 flow;
- activation entity: this activates/deactivates the PM;
- error handling: this handles HEC error conditions.

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ATM-PCI
ATM -SDU (48 octets)
(5 octets)
ATM-PDU
ATM layer
53 octets (note)
TC SL-ATM border
PL-SAP
TC sublayer
TC-PCI
1 octet
TC-PCU
53 octets
PM SL-TC SL border
PM-SDU Logical bit
PM sublayer
PM -PDU
Waveform
Legend:
PCI fields ATM layer related.
PCI field TC sublayer related (HEC field).
NOTE: The use of the last octet of the ATM-PCI is reserved to the TC-sublayer.
Figure 4: PL data units
6.1.4 Physical layer primitives
On the basis of the model identified in the above section, two types of primitives are defined in the PL: the
primitives across the PL-SAP, between the PL (TC sub-layer) and the ATM layer, and the primitives
across the SAP between the PL and the PL management.
In addition internal primitives between the TC sub-layer and the PM sub-layer are defined. As no SAP is
introduced between the two sub-layers (see figure 3), the conventions used for the names of the primitives
exchanged across this boundary are not the standard Open Systems Interconnection (OSI); invoke and
signal type of primitives are used in place of request and indication.

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6.1.4.1 Primitives between the PL and the ATM layer
PL_UNITDATA.request
Function:
This primitive requests the transfer of an ATM-PDU (TC-SDU) from a local ATM-LE.
Semantics of service primitive:
PL_UNITDATA.request (
Data
)
The Data parameter contains the TC-SDU to be transferred.
When generated:
This primitive is generated by a ATM-LE to transfer an ATM-PDU to a peer ATM-LE or to peer ATM-LEs.
Effect on receipt:
In the case of the cell based option, the receipt of this primitive causes the TC-SLE to:
- perform the Cyclic Redundancy Check (CRC) calculation over the first four octets of the TC-SDU to
generate the HEC of the ATM-PCI;
- apply the Distributed Sample Scrambler (DSS) over the entire TC-PDU;
- modify the first two bits of the HEC field according to DSS synchronization mechanism.
Additional comments:
The name UNITDATA has been chosen coherently with the name used in case of unacknowledged
information transfer.
PL_UNITDATA.indication
Function:
This primitive indicates the delivery of a TC-SDU to a local ATM-LE. In the absence of errors, the
delivered TC-SDU will be identical to the ATM-PDU sent by the corresponding remote peer ATM-LE in a
PL_UNITDATA.request primitive.
Semantics of service primitive:
PL_UNITDATA.indication (
Data
)
The Data parameter contains the received TC-SDU where the fifth octet is not significant at the ATM
layer.
When generated:
This primitive is generated by the TC-SLE when a TC-SDU has to be delivered to a local ATM-LE.
TC-SDUs addressed to the PL-LME do not cause the primitive generation.
Idle cells are not TC-SDUs and are neither passed to the ATM-LE nor to the PL-LME.
Effect on receipt:
The receipt of this primitive causes the ATM-LE to activate the ATM-PDU reception procedure.

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Additional comments:
A TC-SDU is obtained by a valid TC-PDU. Valid TC-PDUs are peer TC-PDUs that have been received
with no error or with correctable error in the ATM-PCI according to the HEC verification process.
Depending on the two states HEC verification process a TC-SDU is issued:
- when no errors are detected in the first 4 octets of TC-PDUs, both in Error Detection (ED) and Error
Correction (EC) mode;
- after single bit error correction in EC mode.
6.1.4.2 Primitives between the TC sublayer and the PM sublayer
PM_UNITDATA.invoke
Function:
This primitive requests the transfer of a PM_SDU from a local TC-SLE.
Semantics of service primitive:
PM_UNITDATA.invoke (
Data
)
The Data parameter contains the PM-SDU to be transferred.
When generated:
This primitive is generated by a TC-SLE to transfer a TC-PDU to a peer TC-SLE.
Effect on receipt:
The receipt of this primitive causes the PM-SLE to generate the PM-PDU.
PM_UNITDATA.signal
Function:
This primitive indicates the delivery of a PM-SDU to a local TC-SLE.
Semantics of service primitive:
PM_UNITDATA.signal (
Data
)
The Data parameter contains the received PM-SDU.
When generated:
This primitive is generated by the PM-SLE when a PM-SDU has to be delivered to a local TC-SLE.
Effect on receipt:
The effect of this primitive is dependent upon the state of the TC-SLE HEC cell delineation procedure.
6.1.4.3 Primitives between the PL and the PL management
For further study.

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6.1.5 OAM related to the PL
The required OAM functions relating to the PL are outlined in ITU-T Recommendations I.432 [4] and
I.610 [5].
6.2 ATM layer
The characteristics of the ATM layer are independent of the PM.
6.2.1 ATM layer functions
6.2.1.1 Cell multiplexing and demultiplexing
In the transmit direction, the cell multiplexing function combines cells from individual Virtual Paths (VPs)
and Virtual Channels (VCs) into a non-continuous cell flow. In the receive direction, the cell demultiplexing
function directs individual cells from a non-continuo
...