SIST I-ETS 300 464 E1:2003

Broadband Integrated Services Digital Network (B-ISDN); Asynchronous Transfer Mode (ATM); ATM layer cell transfer performance for B-ISDN connection types

To determine network performance parameters for B-ISDN connection types during the cell transfer phase.

Širokopasovno digitalno omrežje z integriranimi storitvami (B-ISDN) – Asinhroni prenosni način (ATM) – Celična prenosna zmogljivost na plasti ATM za tipe zvez v B-ISDN

General Information

• 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 I-ETS 300 464 ed.1 (1996-02) - Broadband Integrated Services Digital Network (B-ISDN); Asynchronous Transfer Mode (ATM); ATM layer cell transfer performance for B-ISDN connection types

Standards Content (Sample)

SLOVENSKI STANDARD
SIST I-ETS 300 464 E1:2003
01-december-2003
âLURNRSDVRYQRGLJLWDOQRRPUHåMH]LQWHJULUDQLPLVWRULWYDPL%,6'1±$VLQKURQL
SUHQRVQLQDþLQ$70±&HOLþQDSUHQRVQD]PRJOMLYRVWQDSODVWL$70]DWLSH]YH]Y
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Broadband Integrated Services Digital Network (B-ISDN); Asynchronous Transfer Mode
(ATM); ATM layer cell transfer performance for B-ISDN connection types
Ta slovenski standard je istoveten z: I-ETS 300 464 Edition 1
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
SIST I-ETS 300 464 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST I-ETS 300 464 E1:2003

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SIST I-ETS 300 464 E1:2003
INTERIM
EUROPEAN I-ETS 300 464
TELECOMMUNICATION February 1996
STANDARD
Source: ETSI TC-NA Reference: DI/NA-042119
ICS: 33.020, 33.080
ATM, B-ISDN, performance
Key words:
Broadband Integrated Services Digital Network (B-ISDN);
Asynchronous Transfer Mode (ATM);
ATM layer cell transfer performance for
B-ISDN connection types
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 1996. All rights reserved.

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I-ETS 300 464: February 1996
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
1 Scope .7
2 Normative references.7
3 Symbols and abbreviations .8
4 Performance model.8
5 ATM cell transfer outcomes .10
5.1 Successful cell transfer outcome.11
5.2 Errored cell outcome.12
5.3 Lost cell outcome.12
5.4 Misinserted cell outcome .12
5.5 Severely errored cell block outcome.12
6 ATM performance parameters .12
6.1 Severely errored cell block ratio.12
6.2 Cell error ratio .13
6.3 Cell loss ratio .13
6.4 Cell misinsertion rate .13
6.5 Cell transfer delay .13
6.5.1 Mean cell transfer delay .13
6.5.2 Cell Delay Variation (CDV).13
6.5.2.1 1-point CDV at an MP.14
6.5.2.2 Cell delay variation between two MPs (2-point CDV) .15
6.6 Cell flow related parameters .16
7 Performance objectives.16
Annex A (normative): Relationship between ATM layer NP and the NP of AAL type 1 for CBR
services .17
A.1 Possible AAL functions and their effects.17
A.1.1 Lost and misinserted AAL SDUs .17
A.1.2 Errored AAL SDUs.17
A.1.3 AAL SDUs Cell transfer delay.17
A.2 Relationships between NP parameters and binary errors.17
Annex B (normative): Cell transfer delay, 1-point CDV, and 2-point CDV characteristics .18
B.1 Components of delay associated with ATM-based user information transfer.18
B.2 Relationship between cell clumping and distributed cell queues .18
B.3 Relationship between 2-point CDV and cell loss in a shared buffer.19
B.4 Allocation of 2-point CDV values.19
Annex C (normative): Cell transfer performance measurement methods.20
C.1 Cell error ratio.21
C.2 Cell loss ratio.21

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I-ETS 300 464: February 1996
C.3 Cell misinsertion rate . 22
C.4 Severely errored cell block ratio . 22
C.5 Cell transfer delay. 22
C.6 Cell delay variation. 22
C.7 Number of non conforming cells. 23
History. 26

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I-ETS 300 464: February 1996
Foreword
This Interim European Telecommunication Standard (I-ETS) has been produced by the Network Aspects
(NA) Technical Committee of the European Telecommunications Standards Institute (ETSI).
An ETSI standard may be given I-ETS status either because it is regarded as a provisional solution ahead
of a more advanced standard, or because it is immature and requires a "trial period". The life of an I-ETS
is limited to three years after which it can be converted into an ETS, have it's life extended for a further
two years, be replaced by a new version, or be withdrawn.
Proposed announcement date
Date of adoption of this I-ETS: 16 February 1996
Date of latest announcement of this I-ETS (doa): 31 May 1996

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Blank page

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1 Scope
This Interim European Telecommunication Standard (I-ETS) defines speed and accuracy performance
parameters and values for cell transfer in the Asynchronous Transfer Mode (ATM) layer of a Broadband
Integrated Services Digital Network (B-ISDN). The defined parameters and values apply to end-to-end
ATM connections and to specified portions of such connections. The parameters are defined on the basis
of ATM cell transfer reference events which may be observed at physical interfaces between ATM
networks and associated customer equipment, and at physical interfaces between ATM networks. The
values characterize the ATM layer performance for B-ISDN connection types.
NOTE: The parameters defined in this I-ETS may be augmented or modified based upon
further study of the requirements of the services to be supported on B-ISDNs.
The defined parameters apply to compliant connections or connection portions. The
criteria for deciding a connection or a connection portion as compliant or not need to
be defined. These criteria such as the ratio of non conforming cells may be operator
specific.
It is intended that one or more ATM connection performance objectives will be
specified for each of the defined parameters.
Each value applies to ATM connections in their available state. Dependability aspects
will be considered in separate standards.
This I-ETS provides a theoretical framework for the measurement of the performance
parameter values. In some instances they may not be directly applied for real network
measurements, and need to be approximated.
2 Normative references
This I-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 I-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.826 (1994): "Error performance parameters and
objectives for international, constant bit rate digital paths at or above the primary
rate".
[2] ITU-T Recommendation I.150 (1993): "B-ISDN asynchronous transfer mode
functional characteristics".
[3] ITU-T Recommendation I.353 (1993): "Reference events for defining".
[4] ITU-T Recommendation I.363 (1993): "B-ISDN ATM adaptation layer (AAL)
specification".
[5] ITU-T Recommendation I.371 (1993): "Traffic control and congestion control in
B-ISDN".
[6] ITU-T Recommendation I.610 (1993): "B-ISDN operation and maintenance
principles and functions".

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3 Symbols and abbreviations
For the purposes of this I-ETS, the following abbreviations apply:
AAL ATM Adaptation Layer
ATM Asynchronous Transfer Mode
BER Bit Error Ratio
BIP Bit Interleave Parity
CBR Constant Bit Rate
CDV Cell Delay Variation
CEQ Customer Equipment
CER Cell Error Ratio
CLR Cell Loss Ratio
CMR Cell Misinsertion Rate
CRE Cell Reference Event
CTD Cell Transfer Delay
FS Frontier Station
HEC Header Error Control
ISC International Switching Center
ISDN Integrated Services Digital Network
MP Measurement Point
MPI International Measurement Point
MPT Measurement Point, located at the T reference point
B
NCCR Non Conforming Cell Ratio
NNI Network Node Interface
NP Network Performance
NPC Network Parameter Control
NT Network Termination
OAM Operation Administration and Maintenance
PDH Plesiochronous Digital Hierarchy
PL Physical Layer
SDH Synchronous Digital Hierarchy
SDU Service Data Unit
SECBR Severely Errored Cell Block Ratio
SN Sequence Number
SSN Signalling Switching Node
STM Synchronous Transfer Mode
TE Terminal Equipment
UNI User Network Interface
UPC Usage Parameter Control
VBR Variable Bit Rate
VC Virtual Channel
VCC Virtual Channel Connection
VP Virtual Path
VPC Virtual Path Connection
4 Performance model
ITU-T Recommendation I.353 [3] defines Measurement Points (MPs) and associated reference events
that provide a basis for ISDN performance description. ATM cell transfer performance is measured by
observing the reference events created as ATM cells cross MPs.
For B-ISDN, the MPs are ideally located at interfaces where the ATM layer is accessible. For broadband
ISDN two types of MP are defined:
- an ingress MP is located at the input of the first equipment which accesses the ATM layer in a
network operator domain;
- an egress MP is located at the output of the last equipment which accesses the ATM layer in a
network operator domain.
For B-ISDN, the location of the MPI is on the international side of the International Switching Center (ISC)
(or Frontier Station (FS), if the FS accesses the ATM layer) at:

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- the last egress MP in a given country; and
- the first ingress MP in a given country.
For B-ISDN, the Measurement Point, located at the T reference point (MPT) is conceptually located at the
B
interface (the T reference point) that separates the network operator domain and the customer
B
equipment or private network domain. Since a given ATM layer connection (VPC or VCC) is likely to
terminate within the Customer Equipment (CEQ), the ATM reference events detailed is this I-ETS may not
be directly observable at the MPT. Practical guidance on measurement at the MPT are under study.
Two possible methods are :
- locating a physical test set at the UNI; and
- approximation by measuring within the network at the nearest point to the MPT at which the ATM
layer is observable.
Figure 1 illustrates the layered nature of B-ISDN performance issues. The Network Performance (NP)
provided to B-ISDN users depends on the performance of three layers:
- the physical layer, which may be based on Plesiochronous Digital Hierarchy (PDH), Synchronous
Digital Hierarchy (SDH), or cell-based transmission systems. This layer is terminated at points
where a virtual channel or virtual path is switched by equipment using the ATM technique, and thus
has no end-to-end significance when such switching occurs;
- the ATM layer, which is cell-based. The ATM is physical media and application independent and
has end-to-end MPT significance;
- the ATM adaptation layer (AAL), which may enhance the performance provided by the ATM layer to
meet the needs of higher layers. The AAL supports multiple protocol types, each providing different
functions and different performance.
Qualitative relationships between ATM layer NP and the NP provided by the Type 1 AAL are described in
annex A. It is intended that quantitative relationships between ATM layer network performance and the
performance of the physical layer and AAL will be developed.
In the context of ITU-T Recommendation I.353 [3] and of this I-ETS:
- a cell exit event occurs when an ATM cell crosses an MP out of a TE, or crosses an MP out of an
SSN;
- a cell entry event occurs when an ATM cell crosses an MP into a TE or crosses an MP into a SSN.
NOTE: For practical measurement purposes, reference events can be observed at a physical
location that differs from the actual MP. In cases where reference events are
monitored at a physical interface, the time of occurrence of an actual exit can best be
approximated by the observation of the first bit of the unit of control or user information
out of the SSN or CEQ. The time of occurrence of an entry event can best be
approximated by the observation of the last bit of the unit of control or user information
into the SSN or CEQ.

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NP for AAL TYPE 1
NP for AAL TYPE 2
NP for AAL TYPE 3/4
NP for AAL TYPE 5
5   3/4   2   1
1   2   3/4   5
AAL AAL
NETWORK
ATM ATM
PERFORMANCE
ETS 300 464
PL
PL
ATM
PL PL
Switch or cross-connect
Physical layer
using ATM transfer mode
(CCITT Recommendation
G.826 [1] allocated)
Transmission systems SDH, PDH
"cell-based" including STM
(i.e. non-ATM) switching equipment.
Figure 1: Layered model of performance for B-ISDN
5 ATM cell transfer outcomes
In the following, it is assumed that the sequence of ATM cells on a Virtual Channel Connection (VCC) or
Virtual Path Connection (VPC) is preserved (see ITU-T Recommendation I.150 [2]). Two events are said
to be corresponding if they occur on a predefined connection and at a pair of predefined boundaries.
By considering two cell transfer reference events, CRE and CRE at MP and MP respectively, a
1 2 1 2
number of possible cell transfer outcomes may be defined. A transmitted cell is either successfully
transferred, errored, or lost. A received cell for which no corresponding transmitted cell exists is said to be
misinserted. Cell misinsertion can occur as a result of errors in the cell header. Figure 2 illustrates the cell
transfer outcome definitions.

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I-ETS 300 464: February 1996
MP1 MP2
Successfully transferred
CRE1
cell outcome
0
t < Tmax
CRE2
correct payload
and
valid header
Errored cell outcome
CRE1
t < Tmax
CRE2
incorrect payload
and/or
invalid header
CRE2
Misinserted
cell outcome
See note
Lost cell outcome
CRE1
XXX
CRE1
t > Tmax
CRE2
See note
NOTE: Outcome occurs independent of cell content.
Figure 2: Cell transfer outcomes
Methods for estimating cell transfer outcomes either in service or out of service are provided in annex C.
5.1 Successful cell transfer outcome
A successful cell transfer outcome occurs when a CRE corresponding to CRE happens within a
2 1
specified time Tmax of CRE , and (1) the binary content of the received cell information field conforms
1
exactly with that of the corresponding transmitted cell and (2) the cell is received with a valid header field.

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5.2 Errored cell outcome
An errored cell outcome occurs when a CRE corresponding to CRE happens within a specified time
2 1
Tmax of CRE , but (1) the binary content of the received cell information field differs from that of the
1
corresponding transmitted cell (i.e., one or more bit errors exist in the received cell information field) or (2)
the cell is received with an invalid header field after Header Error Control (HEC) procedures are
completed.
Most cells with header errors that are undetected or miscorrected by the HEC will be misdirected by the
ATM layer procedures with the result that no CRE occurs.
2
These cell transfer attempts will be classified as lost cell outcomes.
5.3 Lost cell outcome
A lost cell outcome occurs when a CRE fails to happen within time Tmax of the corresponding CRE .
2 1
NOTE: The characteristics of the connections are negotiated in the traffic contract (see ITU-T
Recommendation I.371 [5]). Cell losses attributable to cells non conforming to the
negotiated traffic contract shall be excluded in assessing the performance of the
network.
Cell losses attributable to customer equipment shall also be excluded in assessing the
performance of the network. Estimation of cell losses occurring in customer equipment
due to network causes is for further study.
5.4 Misinserted cell outcome
Misinserted cell outcome occurs when a CRE happens without a corresponding CRE .
2 1
5.5 Severely errored cell block outcome
A cell block is a sequence of N cells transmitted consecutively on a given connection. A severely errored
cell block outcome occurs when more than M errored cell, lost cell, or misinserted cell outcomes are
observed in a received cell block.
This definition applies to the case when all cells are conforming to the traffic contract (see ITU-T
Recommendation I.371 [5]). The definition of severely errored cell block outcome in case when some cells
are non conforming to the traffic contract is for further study.
For practical measurement purposes, a cell block will normally correspond to the number of user
information cells transmitted between successive OAM cells. The size N of a cell block and the value of M
are to be specified in a later version of this I-ETS.
6 ATM performance parameters
This clause defines a set of ATM cell transfer performance parameters using the cell transfer outcomes
defined in clause 5 (see also annex B). All parameters may be estimated on the basis of observations at
the MPs. Cell transfer performance measurement methods are described in annex C.
6.1 Severely errored cell block ratio
Severely Errored Cell Block Ratio (SECBR) is the ratio of total severely errored cell blocks to total cell
blocks in a population of interest.
NOTE: The severely errored cell block outcome and parameter provide a means of preventing
bursts of cell transfer failures from inappropriately influencing the observed values for
cell error ratio, cell loss ratio, cell misinsertion rate, and the associated availability
parameters.

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6.2 Cell error ratio
Cell Error Ratio (CER) is the ratio of total errored cells to total successfully transferred cells plus errored
cells in a population of interest. Successfully transferred cells and errored cells contained in cell blocks
counted as severely errored cell blocks should be excluded from the population used in calculating cell
error ratio (see subclause 6.1).
6.3 Cell loss ratio
Cell Loss Ratio (CLR) is the ratio of total lost cells to total transmitted cells in a population of interest. The
total number of lost cells is computed as the total number of cells which are lost in excess of the total
number of non conforming cells to the negotiated traffic contract. The total number of transmitted cells is
computed as the number of cells which are conforming to the negotiated traffic contract.
Lost cells and transmitted cells in cell blocks counted as severely errored cell blocks should be excluded
from the population used in calculating cell loss ratio (see subclause 6.1).
6.4 Cell misinsertion rate
Cell Misinsertion Rate (CMR) is the total number of misinserted cells observed during a specified time
1)
interval divided by the duration of the time interval (i.e. the number of misinserted cells per unit of time) .
Misinserted cells and time intervals associated with cell blocks counted as severely errored cell blocks
should be excluded from the population used in calculating cell misinsertion rate (see subclause 6.1).
6.5 Cell transfer delay
Cell Transfer Delay (CTD) is the time, t - t , between the occurrence of two corresponding cell transfer
2 1
events, CRE at time t . and CRE at time t ,where t > t and t - t ≤ Tmax.
1 1 2 2 2 1 2 1
NOTE 1: The value of Tmax is for further study.
NOTE 2: t and t are measured with the same reference time.
1 2
6.5.1 Mean cell transfer delay
Mean cell transfer delay is the arithmetic mean of a specified number of cell transfer delays.
6.5.2 Cell Delay Variation (CDV)
Two cell transfer performance parameters associated with Cell Delay Variation (CDV) are defined. The
first parameter, 1-point cell delay variation, is defined on the basis of observation of a sequence of
consecutive cell arrivals at a single MP. The second parameter, 2-point cell delay variation, is defined on
the basis of observations of corresponding cell arrivals at two MPs that delimit a virtual connection portion.
The 1-point CDV parameter describes variability in the pattern of cell arrival (entry or exit) events at an MP
with reference to the negotiated peak cell rate 1/T (see ITU-T Recommendation I.371 [5]), it includes
variability present at the cell source (customer equipment) and the cumulative effects of variability
introduced (or removed) in all connection portions between the cell source and the specified MP. It is
related to cell conformance at the MP, and to network queues. It is also related to the buffering
procedures used in AAL 1 of the receiving side to compensate for cell delay variation. The 2-point CDV
parameter describes variability in the pattern of cell arrival events at the output of a connection portion
(e.g. measurement point MP2) with reference to the pattern of corresponding events at the input to the
portion (e.g. measurement point MP1): it includes only variability introduced within the connection portion.
It provides a direct measure of portion performance and an indication of the maximum (aggregate) length
of cell queues that may exist within the portion. Additional information on relationships of these CDV
related parameters to cell queues and their application in ATM network performance specification is
provided in annex B.

1)
By definition, a misinserted cell is a received cell that has no corresponding transmitted cell. Cell misinsertion on a particular
connection is most often caused by an undetected error in the header of a cell being transmitted on a different connection.
Since the mechanism that most often causes misinserted cells is independent of the number of cells transmitted on the
observed connection, this performance parameter cannot be expressed as a ratio, only as a rate.

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6.5.2.1 1-point CDV at an MP
The 1-point CDV (y ) for cell k at an MP is the difference between the cell's reference arrival time (c ) and
k k
actual arrival time (a ) at the MP (figure 3) : y = c - a . The reference arrival time pattern (c ) is defined
k k k k k
as follows:
==
ca
0
00
=+ when ≥ ,
cc T c a
kk+1 k k
+ otherwise.
aT
k
Positive values of 1-point CDV ("early" cell arrivals) correspond to cell clumping: negative values of 1-point
CDV ("late" cell arrivals) correspond to gaps in the cell stream. The reference pattern defined above
2)
eliminates the effect of gaps in the specification and measurement of cell clumping or more.
Annex C illustrates one measurement method that calculates, for a cell stream received at an MP, the
number of cells that do not conform with a specified peak cell rate at a specified CDV tolerance.
It is anticipated that one or more values for maximum CDV tolerance (τ) will be specified.
NOTE: The reference instant c is defined as the arrival time of the first cell recognized by the
o
1 point CDV mechanism.
REFERENCE CLOCK MP
CELL 0
t = 0
CELL 1 a
c
1
1
T
a
2
CELL 2
c
2
T
c
3
T
a
3
CLOCK SKIP
CELL 3
a
4
c
4 CELL 4
T
a
5
c
5
CELL 5
T
c a
k
k
T
CELL K
Variables:
a = cell k actual arrival time at MP
k
c = cell k reference arrival time at MP y = c - a
k k k k
y = 1-point CDV
k
Figure 3: Cell delay variation - 1-point definition

2)
The reference clock "skips" by an amount equal to the difference between the actual and expected arrival times immediately
after each "late" cell arrival.

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6.5.2.2 Cell delay variation between two MPs (2-point CDV)
The 2-point CDV (v ) for cell k between MP and MP is the difference between the absolute cell transfer
k 1 2
delay (x ) or cell k between the two MPs and a defined reference cell transfer delay (d ) between the
k 1.2
same two MPs (figure 4) : v = x - d .
k k 1.2
The reference time at the locations of MP and MP is the same.
1 2
3)
The absolute cell transfer delay (x ) of cell k between MP and the MP is the difference between the
k 1 2
cell's actual arrival time at MP (a2 ) and the cell's actual arrival time at MP (a1 ) : x = a2 - a1 . The
2 k 1 k k k k
reference cell transfer delay (d ) between MP and MP is the absolute cell transfer delay experienced
1.2 1 2
by cell 0 between the two MPs.
Positive values of 2-point CDV correspond to cell transfer delays greater than that experienced by the
reference cell; negative values of 2-point CDV correspond to cell transfer delays less than that
experienced by the reference cell. The distribution of 2-point CDV is identical to the distribution of absolute
cell transfer delay for any specified population of transferred cells. It is anticipated that the specification of
2-point CDV objectives will be in terms of upper and lower quantiles. The specified upper and lower
quantile values may depend on the negotiated peak cell rate.
Annex C illustrates one method of estimating the
...