SIST EN 301 163-2-1 V1.1.2:2003

SLOVENSKI STANDARD
SIST EN 301 163-2-1 V1.1.2:2003
01-december-2003
3UHQRVLQPXOWLSOHNVLUDQMH70±*HQHULþQH]DKWHYHSUHQRVQHIXQNFLRQDOQRVWL
DVLQKURQHJDSUHQRVQHJDQDþLQD$70YVDPLRSUHPL±GHO)XQNFLMVNLPRGHO
UDYQLQH]DXSUDYOMDQMHSUHQRVDLQSODVWL
Transmission and Multiplexing (TM); Generic requirements of Asynchronous Transfer
Mode (ATM) transport functionality within equipment; Part 2-1: Functional model for the
transfer and layer management plane
Ta slovenski standard je istoveten z: EN 301 163-2-1 Version 1.1.2
ICS:
33.040.20 Prenosni sistem Transmission systems
SIST EN 301 163-2-1 V1.1.2:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003

---------------------- Page: 2 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
EN 301 163-2-1 V1.1.2 (1999-05)
European Standard (Telecommunications series)
Transmission and Multiplexing (TM);
Generic requirements of Asynchronous Transfer Mode (ATM)
transport functionality within equipment;
Part 2-1: Functional model for the transfer
and layer management plane

---------------------- Page: 3 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
2 EN 301 163-2-1 V1.1.2 (1999-05)
Reference
DEN/TM-01016-2-1 (aroi9idc.PDF)
Keywords
ATM, transport, B-ISDN, SDH, transmission
ETSI
Postal address
F-06921 Sophia Antipolis Cedex - FRANCE
Office address
650 Route des Lucioles - Sophia Antipolis
Valbonne - FRANCE
Tel.: +33 4 92 94 42 00  Fax: +33 4 93 65 47 16
Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88
Internet
secretariat@etsi.fr
Individual copies of this ETSI deliverable
can be downloaded from
http://www.etsi.org
If you find errors in the present document, send your
comment to: editor@etsi.fr
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 1999.
All rights reserved.
ETSI

---------------------- Page: 4 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
3 EN 301 163-2-1 V1.1.2 (1999-05)
Contents
Intellectual Property Rights.5
Foreword .5
1 Scope.6
2 References.6
3 Definitions, abbreviations and symbols.7
3.1 Definitions.7
3.2 Abbreviations .7
3.2.1 Modelling specific abbreviations.7
3.2.2 General abbreviations .8
3.3 Symbols and diagrammatic conventions.9
3.4 Introduction .9
4 Transmission path to ATM virtual path adaptation functions .11
4.1 S3 path adaptation functions .11
4.1.1 S3 path to ATM virtual path adaptation source function S3/Avp_A_So.11
4.1.2 S3 path to ATM virtual path adaptation sink function S3/Avp_A_Sk.15
4.2 S4 path adaptation functions .18
4.2.1 S4 path to ATM virtual path adaptation source function S4/Avp_A_So.18
4.2.2 S4 path to ATM virtual path adaptation sink function S4/Avp_A_Sk.23
4.3 S4-4v path adaptation functions .26
4.3.1 S4-4v path to ATM virtual path adaptation source function S4-4v/Avp_A_So.26
4.3.2 S4-4v path to ATM virtual path adaptation sink function S4-4v/Avp_A_Sk .26
4.4 S4-4c path layer adaptation functions.27
4.4.1 S4-4c path to ATM virtual path adaptation source function S4-4c/Avp_A_So.27
4.4.2 S4-4c path to ATM virtual path adaptation sink function S4-4c/Avp_A_Sk.27
4.5 Cell based adaptation functions.27
4.6 P12s path adaptation functions.27
4.6.1 P12s path to ATM virtual path adaptation source function P12s/Avp_A_So.27
4.6.2 P12s path to ATM virtual path adaptation sink function P12s/Avp_A_Sk.30
4.7 P31s path adaptation functions.34
4.7.1 P31s path to ATM virtual path adaptation source function P31s/Avp_A_So.34
4.7.2 P31s path to ATM virtual path adaptation sink function P31s/Avp_A_Sk.38
5 ATM virtual path layer network functions .41
5.1 ATM virtual path connection function Avp_C.42
5.2 ATM virtual path trail termination functions.43
5.2.1 ATM virtual path trail termination source function Avp_TT_So .43
5.2.2 ATM virtual path trail termination sink function Avp_TT_Sk .44
5.3 ATM virtual path monitoring functions.47
5.3.1 ATM virtual path non-intrusive monitoring function Avpm_TT_Sk.47
5.4 ATM virtual path segment functions .50
5.4.1 ATM virtual path segment trail termination source function AvpS_TT_So.50
5.4.2 ATM virtual path segment trail termination sink function AvpS_TT_Sk.51
5.4.3 ATM virtual path segment to ATM virtual path adaptation source function AvpS/Avp_A_So .53
5.4.4 ATM virtual path segment to ATM virtual path adaptation sink function AvpS/Avp_A_Sk .54
5.5 ATM virtual path traffic management functions .54
5.5.1 ATM virtual path traffic management trail termination source function AvpT_TT_So .55
5.5.2 ATM virtual path traffic management trail termination sink function AvpT_TT_Sk.56
5.5.3 ATM virtual path traffic management to ATM virtual path adaptation source function
AvpT/Avp_A_So.57
5.5.4 ATM virtual path traffic management to ATM virtual path adaptation sink function
AvpT/Avp_A_Sk.58
5.6 ATM virtual path loopback functions.59
5.6.1 ATM virtual path loopback source function Avplb_TT_So .59
5.6.2 ATM virtual path loopback sink function Avplb_TT_Sk.60
ETSI

---------------------- Page: 5 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
4 EN 301 163-2-1 V1.1.2 (1999-05)
6 ATM virtual path to ATM virtual channel adaptation functions.62
6.1 ATM virtual path to ATM virtual channel adaptation source function Avp/Avc_A_So.62
6.2 ATM virtual path to ATM virtual channel adaptation sink function Avp/Avc_A_Sk.63
7 ATM virtual channel layer network functions.66
7.1 ATM virtual channel connection function Avc_C.67
7.2 ATM virtual channel trail termination functions .68
7.2.1 ATM virtual channel trail termination source function Avc_TT_So .68
7.2.2 ATM virtual channel trail termination sink function Avc_TT_Sk.70
7.3 ATM virtual channel monitoring functions .72
7.3.1 ATM virtual channel non-intrusive monitoring function Avcm_TT_Sk.72
7.4 ATM virtual channel segment functions.75
7.4.1 ATM virtual channel segment trail termination source function AvcS_TT_So.75
7.4.2 ATM virtual channel segment trail termination sink function AvcS_TT_Sk.76
7.4.3 ATM virtual channel segment to ATM virtual channel adaptation source function AvcS/Avc_A_So.78
7.4.4 ATM virtual channel segment to ATM virtual channel adaptation sink function AvcS/Avc_A_Sk.79
7.5 ATM virtual channel traffic management functions .80
7.5.1 ATM virtual channel traffic management trail termination source function AvcT_TT_So.80
7.5.2 ATM virtual channel traffic management trail termination sink function AvcT_TT_Sk.81
7.5.3 ATM virtual channel traffic management to ATM virtual channel adaptation source function
AvcT/Avc_A_So .82
7.5.4 ATM virtual channel traffic management to ATM virtual channel adaptation sink function
AvcT/Avc_A_Sk .83
7.6 ATM virtual channel loopback functions .84
7.6.1 ATM virtual channel loopback source function Avclb_TT_So.84
7.6.2 ATM virtual channel loopback sink function Avclb_TT_Sk.85
8 ATM virtual channel to ATM client adaptation functions .87
8.1 ATM virtual channel to ATM client adaptation source function Avc/XXX_A_So .87
8.2 ATM virtual channel to ATM Client Adaptation Sink function Avc/XXX_A_Sk.88
Bibliography.90
History.91
ETSI

---------------------- Page: 6 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
5 EN 301 163-2-1 V1.1.2 (1999-05)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by ETSI Technical Committee Transmission
and Multiplexing (TM), in order to provide inter-vendor and inter-operator compatibility of Asynchronous Transfer
Mode (ATM) equipment.
The present document is part 2 of a multi-part EN covering the generic requirements of Asynchronous Transfer Mode
(ATM) transport functionality within equipment, as identified below:
Part 1: "Functional characteristics and equipment performance";
Part 2: "Functional model for the transfer and layer management plane".
National transposition dates
Date of adoption of this EN: 23 April 1999
Date of latest announcement of this EN (doa): 31 July 1999
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 January 2000
Date of withdrawal of any conflicting National Standard (dow): 31 January 2000
ETSI

---------------------- Page: 7 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
6 EN 301 163-2-1 V1.1.2 (1999-05)
1 Scope
The purpose of the present document is to provide specifications for Asynchronous Transfer Mode (ATM) equipment to
be used in the ETSI region. Such specifications will ensure compatibility between equipment by identifying which
functions are mandatory for interworking and which can be considered as truly optional. Of course it is not the intention
to prevent manufacturers or procurers from following an alternative specification, but the consequences should become
clear from the present document.
The document will be in two parts, producing a list of functions and processes in the first part and a formal
representation of transfer transport and layer management functions in the second part. The specification will take
advantage of the work done in ITU but will take the work further with an ETSI European view. This means: the
identification of ITU options to be mandatory in Europe, deletion of options not required for Europe, creation of new or
revised descriptions where necessary, identification of guideline or benchmark performance parameters for classes of
equipment.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
• A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
[1] ETS 300 147: "Transmission and Multiplexing (TM); Synchronous Digital Hierarchy (SDH);
Multiplexing structure".
[2] ETS 300 298-1: "Broadband Integrated Services Digital Network (B-ISDN); Asynchronous
Transfer Mode (ATM); Part 1: B-ISDN ATM functional characteristics
[ITU-T Recommendation I.150 (1995)]".
[3] ETS 300 298-2: "Broadband Integrated Services Digital Network (B-ISDN); Asynchronous
Transfer Mode (ATM); Part 2: B-ISDN ATM layer specification".
[4] ETS 300 300 (1997): "Broadband Integrated Services Digital Network (B-ISDN); Synchronous
Digital Hierarchy (SDH) based user network access; Physical layer User Network Interfaces (UNI)
for 155 520 kbit/s and 622 080 kbit/s Asynchronous Transfer Mode (ATM) B-ISDN applications".
[5] EN 300 301 (V1.2): "Broadband Integrated Services Digital Network (B-ISDN); Traffic control
and congestion control in B-ISDN".
[6] ETS 300 337: "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".
[7] ETS 300 354: "Broadband Integrated Services Digital Network (B-ISDN); B-ISDN Protocol
Reference Model (PRM)".
[8] ETS 300 404: "Broadband Integrated Services Digital Network (B-ISDN); B-ISDN Operation And
Maintenance (OAM) principles and functions".
[9] EN 300 417-1-1 (V1.1): "Transmission and Multiplexing (TM); Generic requirements of transport
functionality of equipment; Part 1-1: Generic processes and performance".
ETSI

---------------------- Page: 8 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
7 EN 301 163-2-1 V1.1.2 (1999-05)
[10] ITU-T Recommendation G.707: "Network node interface for the synchronous digital hierarchy
(SDH)".
[11] ITU-T Recommendation G.803: "Architecture of transport networks based on the synchronous
digital hierarchy (SDH)".
[12] ITU-T Recommendation G.804: "ATM cell mapping into plesiochronous digital hierarchy (PDH)".
[13] ITU-T Recommendation G.805: "Generic functional architecture of transport networks".
[14] ITU-T Recommendation G.832: "Transport of SDH elements on PDH networks: Frame and
multiplexing structures".
[15] ITU-T Recommendation I.150: "B-ISDN asynchronous transfer mode functional characteristics".
[16] ITU-T Recommendation I.321: "B-ISDN protocol reference model and its application".
[17] ITU-T Recommendation I.326: "Functional architecture of transport networks based on ATM".
[18] ITU-T Recommendation I.361: "B-ISDN ATM layer specification".
[19] ITU-T Recommendation I.371: "Traffic control and congestion control in B-ISDN".
[20] ITU-T Recommendation I.432: "B-ISDN user-network interface - Physical layer specification".
[21] ITU-T Recommendation I.432.1: "B-ISDN user-network interface - Physical layer specification:
General characteristics".
[22] ITU-T Recommendation I.432.2: "B-ISDN user-network interface - Physical layer specification:
155 520 kbit/s and 622 080 kbit/s operation".
[23] ITU-T Recommendation I.610: "B-ISDN operation and maintenance principles and functions".
[24] ITU-T Recommendation I.732: "Functional characteristics of ATM equipment".
3 Definitions, abbreviations and symbols
3.1 Definitions
For the purposes of the present document, the terms and definitions given in EN 300 417-1-1 [9] apply.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3.2.1
Modelling specific abbreviations
A Adaptation function
a consequent action
AI Adapted Information
AP Access Point
APId Access Point Identifier
C Connection function
c defect cause
CI Characteristic Information
CK ClocK
CP Connection Point
D Data
d defect correlation
ETSI

---------------------- Page: 9 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
8 EN 301 163-2-1 V1.1.2 (1999-05)
G Group
L Layer
m monitoring function
MI Management Information
P12s 2 048 kbit/s PDH path layer with synchronous 125 ms frame structure
P31s 34 368 kbit/s PDH path layer with synchronous 125 ms frame structure
RI Remote Information
S Segment
S4 VC-4 path layer
Sk Sink
So Source
SSF Server Signal Fail
T Traffic management
TI Timing Information
TT Trail Termination function
vc virtual channel
vp virtual path
3.2.2
General abbreviations
AAL ATM Adaptation Layer
ACS ATM Cell Start
AIS Alarm Indication Signal
ATM Asynchronous Transfer Mode
BRPM Backward Report Performance Monitoring
CBDS Connectionless Broadband Data Service
CC Continuity Check
CCAD Continuity Check Activation/Deactivation
CLP Cell Loss Priority
CNGI CoNGestion Indication
dLCD Loss of Cell Delineation defect
EFCI Explicit Forward Congestion Indicator
EMF Element Management Function
F_DS Far-end Defect Second
FS Frame Start signal
GFC Generic Flow Control
HDLC High-level Data Link Control procedure
HEC Header Error Check
Hex Hexadecimal
ID IDentifier
LAN Local Area Network
LB LoopBack
LLID Loopback Location IDentifier
LOC Loss of Continuity
MA Maintenance and Adaptation
N_DS Near-end Defect Second
NE Network Element
N-ISDN Narrowband Integrated Services Digital Network
NNI Network Node Interface
NPC Network Parameter Control
OAM Operation, Administration and Maintenance
OCD Out of Cell Delineation
PDH Plesiochronous Digital Hierarchy
PLM PayLoad Mismatch
PM Performance Monitoring
PMAD Performance Monitoring Activation/Deactivation
POH Path OverHead
PRM Protocol Reference Model
PTI Payload Type Identifier
QoS Quality Of Service
ETSI

---------------------- Page: 10 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
9 EN 301 163-2-1 V1.1.2 (1999-05)
RDI Remote Defect Indicator
RLCD Remote Loss of Cell Delineation
SDH Synchronous Digital Hierarchy
SLOC Segment Loss Of Continuity
SSF Server Signal Fail
TP Timing Point
TP Transmission Path
TSF Trail Signal Fail
UNI User Network Interface
UPC Usage Parameter Control
VC Virtual Channel
VC Virtual Container
VCC Virtual Channel Connection
VP Virtual Path
VPC Virtual Path Connection
VPI Virtual Path Identifier
3.3 Symbols and diagrammatic conventions
For the purposes of the present document, the symbols and diagrammatic conventions described in EN 300 417-1-1 [9]
apply.
3.4 Introduction
The atomic functions used in the Transmission Path (TP) convergence, ATM Virtual Path (VP) and Virtual Channel
(VC) Layer Networks and their associated Adaptation functions are defined in the present document.
The document is structured in the following manner:
• Transmission Path to Avp Adaptation Functions:
- SDH Adaptation Functions;
- Cell Based Adaptation Functions;
- PDH Adaptation Function.
• VP Layer Network, including Connection, Trail Termination, Segment, Traffic Management, Monitoring and
Loopback Functions;
• Avp to Avc Adaptation Functions;
• VC Layer Network, including Connection, Trail Termination, Segment, Traffic Management, Monitoring and
Loopback Functions;
• Avc to ATM Client Layer Adaptation Functions.
The Layer Networks and Adaptation functions are defined for the purpose of the user to group them into a higher level
grouping, if required. The decomposition of the atomic function sequence into Layer Networks and Adaptation functions
correspond to the view of ITU-T Recommendation G.805 [13]. It also represents the common basis view from the
Synchronous Digital Hierarchy (SDH) and ATM history perspective, since ITU-T Recommendation G.803 [11]
(defining SDH networks) as well as ITU-T Recommendation I.326 [17] (defining ATM networks) are both based on
ITU-T Recommendation G.805 [13].
For the SDH view, the grouping used in ITU-T Recommendation G.803 [11] is the Network Layer (or simply called
Layer). It associates the Layer Network and the Adaptation function in Client Layer direction into the grouping called
"Network Layer".
For the ATM view, the grouping used in ITU-T Recommendation I.326 [17] is the Transport Assembly, also called VP
Level resp. VC Level. It associates the Layer Network and the Adaptation function in Server direction into the grouping
called respectively "VP Level" and "VC Level".
ETSI

---------------------- Page: 11 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
10 EN 301 163-2-1 V1.1.2 (1999-05)
Figure 1 shows the grouping of the Adaptation function to the Layer Network according to the two views.
.
SDH view Atom ics G.805 ATM view
G.803 I.326
Avc/XXX
Avc
Avc
Avp/Avc
Avp
Avp
TP/A vp
Figure 1: Different views for the grouping of the adaptation functions
ETSI
TP Layer Avp Layer Avc Layer
Avc Layer Network
Avp Layer N etwork
VP Level VC Lev el

---------------------- Page: 12 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
11 EN 301 163-2-1 V1.1.2 (1999-05)
4 Transmission path to ATM virtual path adaptation
functions
4.1 S3 path adaptation functions
4.1.1 S3 path to ATM virtual path adaptation source function
S3/Avp_A_So
Symbol:
Avp_CI
S3/Avp
S3_T I
S3/Avp_A_So_MI
S3/Avp_RI
.
S3_AI
Figure 2: S3/Avp_A_So symbol
Interfaces:
Table 1: S3/Avp_A_So input and output signals
Input(s) Output(s)
per Avp_CI for each VP configured: S3_AI_D
Avp_CI_D S3_AI_CK
Avp_CI_ACS S3_AI_FS
Avp_CI_SSF
S3_TI_CK
S3_TI_FS
S3/Avp_RI_RLCD
S3/Avp_A_So_MI_Active
S3/Avp_A_So_MI_CellDiscardActive
S3/Avp_A_So_MI_TPusgActive
S3/Avp_A_So_MI_GFCActive
S3/Avp_A_So_MI_VPI-KActive
The S3/Avp_A_So function provides adaptation from the ATM Virtual Path to the VC-3 path. This is performed by a
grouping of Specific Processes and Common Processes as shown in figure 3.
Activation: The function shall access the access point when it is activated (MI_Active is true). Otherwise, it shall not
access the access point.
ETSI

---------------------- Page: 13 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
12 EN 301 163-2-1 V1.1.2 (1999-05)
Avp_CI Avp_CI Avp_CI
N
VPI=0 VPI=1 VPI=2 -1 Specific
processes
.
Common
processes
S3/Avp_A_So
S3_AI
Figure 3: S3/Avp_A_So atomic function decomposed into Specific and Common processes parts
NOTE 1: The sequential order of the processes within the atomic functions is important. For the correct order, refer
to the ordering of the processes given below.
Specific Processes:
These Processes include VPI setting as well as VP asynchronous multiplexing. Each of these Specific Processes is
N
characterized by the Virtual Path Identifier number K, where 0 £ K £ 2 - 1.
VPI-K Activation: The Specific Processes perform the operation specified below when it is activated (MI_VPI-KActive
is true).
The format of the Characteristic Information (Avp_CI) is given in figure 4.
Cell Header
VPI=K
VPI=K VPI=K VPI=K
CI_ACS CI_ACS CI_ACS CI_ACS
Bit Header O ctet
1 2 3 4 5 6 7 8
VPI 1
VPI
2
3
CLP 4
5
Figure 4: Avp_CI (NNI format)
VPI setting is based on the activation of the Specific function by MI_VPI-KActive and inserts the value of "K" as VPI.
NOTE 2: The value of N represents the number of bits in the VPI field and is an integer number. Its maximum value
is equal to 12 for the ATM NNI. Its maximum value is equal to 8 for the ATM UNI.
VP multiplexing: Asynchronous multiplexing is performed for each active Specific function.
ETSI

---------------------- Page: 14 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
13 EN 301 163-2-1 V1.1.2 (1999-05)
Common Processes:
The Common Processes include: Congestion control (selective cell discard (CLP based)), GFC processing, TP usage
measurement, cell rate decoupling, HEC processing, cell information field scrambling, cell stream mapping and
processing of the payload specific bytes C2 and H4, as well as bits 6 and 7 of G1, to the VC-3 Path OverHead (POH).
The logical ordering of the processes from input to output shall be maintained.
Bit Header O ctet
1 2 3 4 5 6 7 8
GFC
1
2
3
4
HEC
5
Figure 5: Cell header information processed in S3/Avp_A_So
12 85
1
2
3
4  ATM Cell
5
6
7
8
9
Figure 6: ATM cell stream mapping into Container-3 structure
12 3 85
1
2
3C2
4G1
(5-7)
5 VC-3 payload ( 9x84 bytes )
6H4
7
8
9
Figure 7: S3_AI_So_D
ETSI

---------------------- Page: 15 ----------------------

SIST EN 301 163-2-1 V1.1.2:2003
14 EN 301 163-2-1 V1.1.2 (1999-05)
Congestion control: If enabled by MI_CellDiscardActive, this function shall perform selective cell discard according to
CLP value. In the event of congestion, cells with CLP = 1 are subject to be discarded prior to cells with CLP = 0. See
EN 300 301 [5] (ITU-T Recommendation I.371 [19]) for further details about the use of the CLP. In the event of
congestion, the Explicit Forward Congestion Indicator (EFCI) marking in the Payload Type Identifier (PTI) field is set
according to ETS 300 298-2 [3] (ITU-T Reco
...