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All drawings appearing in this Recommendation have been done in Autocad.
Recommendation E.502
TRAFFIC MEASUREMENT REQUIREMENTS FOR SPC (ESPECIALLY DIGITAL)
TELECOMMUNICATION EXCHANGES
1 Introduction
This Recommendation applies to all SPC (especially digital)
telecommunications exchanges operating in a switched telephone network and
providing basic telephony service. This Recommendation will be the basis for
measurements in an Integrated Services Digital Network (ISDN).
Traffic measurements on exchanges and surrounding telephone network
provide the data base from which the dimensioning, planning, operation and
management of the telephone network are carried out.
Information gathered from these measurements can be used for:
- identifying traffic patterns and distributions on a route and
destination basis;
- determining the amount of traffic in the exchange and the network;
- monitoring the continuity of service and the grade of service.
The above data and information are gathered with the purpose of supporting
the following fundamental activities:
a) dimensioning, planning and administration of the exchange and
surrounding network;
b) performance monitoring of the exchange and surrounding network;
c) network management;
d) operation and maintenance of the exchange and surrounding network;
e) tariff and marketing studies;
f) forecasting;
g) dimensioning, planning and administration of the common channel
signalling network;
h) performance monitoring of the common channel signalling network.
The information generated by the exchange (see Recommendation Q.544) can
be provided to the end user in either real-time or non real-time (post
processed). The activities being performed by the end user will dictate the speed
of this response: for example, operation and maintenance will require real-time
information while the forecasting and planning information can be provided after
the event in non real-time.
For these activities, the following major processing steps can be
identified:
- generation, collection and storage of data;
- analysis and processing of data;
- presentation and use of the analysis results.
The generation, collection and output of raw data is achieved by
continuous as well as periodic and non-periodic measurements carried out in the
exchange.
The data analysis may be performed by the SPC exchange or by another
system depending on the following:
- total amount of data;
- need for analysis of data from multiple exchange;
- processor load constraints.
For further information see Recommendation E.503.
2 Traffic measurement
2.1 Traffic measurement model
This section establishes the basic structure for a traffic measurement
model that can be applied to measurements of traffic generated by the basic
telephony service.
Measurements of traffic generated by ISDN services and common channel
signalling systems is for further study.
A measurement is identified by three basic elements: time, entities,
objects. Time includes all the necessary information to define the start, the
duration and periodicity of a certain measurement. Entities describe the
quantities for which data collection must be performed with a certain
measurement. Objects are individual items on which the measurements are
performed. Some examples of entities and objects are given below:
Entities:
- traffic volume;
- number of call attempts;
Fascicle II.3 - Rec. E.502 PAGE1
- number of seizures;
- number of successful call attempts;
- number of call attempts for which a delay exceeds a predetermined
threshold value.
Objects:
- subscriber line groups;
- circuit groups;
- common control units;
- auxiliary devices;
- destinations;
- common channel signalling links;
- signal transfer points (STP).
The measurements are classified into different measurement types on the
basis of a measurement matrix in which each row represents an entity and each
column represents an object (Figure 1/E.502).
A measurement type is a particular combination of entities and objects
corresponding to certain entries in the measurement matrix. Part of these
measurement types may be standardized while the rest of them seem to be system-
and/or Administration-dependent. It should be noted that all the entries in the
measurement matrix cannot be used because some of them will be impossible and
some others may be meaningless. In all measurement types, the entities are fixed
although some entities may not be measured for some applications. Selected
objects form an object list. In some measurement types, the object list is fixed.
In other types one can choose for the actual measurement some or all of the
allowed objects. A measurement set is a collection of measurement types.
Figure 1/E.502 - CCITT 47291
2.2 Traffic measurement structure
A traffic measurement consists of:
- measurement set information;
- time information;
- output routing and scheduling information (output parameters).
Measurement set information, time information and output routing and
scheduling information may be predefined as well as object lists. It should be
noted that predefinition characteristic are system-dependent. Time data routing
and the schedule may be fixed.
2.2.1 Measurement set information
Measurement set information consists of one or several selected
measurement types with defined object (object lists) and
measurement-type-dependent parameters (e.g. sampling interval, number of events
in a certain category, destination codes, etc.).
2.2.2 Time information
Measurements may have an undetermined duration (stop date is not
prespecified), or a predetermined duration, or be taken all the time. In
addition, measurements may be performed continuously or on a non-continuous
basis.
For measurements of undetermined duration and performed non-continuously,
the recording days must be determined on a periodic basis (periodicity pattern
within a calendar week). For measurements of predetermined duration, the
recording days may be determined on a periodic basis or by defining the dates of
the recording days (see Figure 2/E.502).
Figure 2/E.502 - CCITT 82070
As shown in Figure 3/E.502, time data are measurement level, recording day
level and recording period level.
Measurement level: Contains information about dates of recording days for
non-periodic measurements or periodicity pattern for periodic measurements.
Recording day level: Contains information about the start and stop time for
recording periods within a recording day.
Recording period level: Contains information about the periodicity of the
data collection, controlled by the result accumulation period. The result
accumulation period can be shorter than the recording period; in that case,
more than one set of data is collected for each of the recording periods, to
be routed toward the output media according to the results output schedule.
Figure 3/E.502 - CCITT 33240
PAGE14 Fascicle II.3 - Rec. E.502
2.2.3 Output routing and scheduling information
Output routing information defines to what destination the produced
measurement results should be routed for the recording; the output routing may be
toward either a physical medium (e.g. printer) or a logical medium (e.g. file).
Output scheduling information defines when (days and time) the output of
the results is to be made. The output of results may be related to the end of the
result accumulation period.
3 Traffic flows
Each type of traffic flow occurring in/through the exchange can be
distinguished by association with an inlet1) or outlet2) of the exchange, or both
The different types of traffic flow for a generalized exchange, viz. one that
combines both local and transit functions and that provides operator
(telephonist) service, are illustrated as shown in Figure 4/E.502:
From Figure 4/E.502 the following relations apply:
A = E + F + G + H + Z1
B = I + J + K + L + Z2
C = O + P
D = M + N + Z3
where Z1, Z2 and Z3 account for traffic flows corresponding to calls with
incomplete or invalid dialling information, and
Q = M + F + K + O - d1
R = N + G + L + P - d2
S = H + J - d3
T = E + I - d4
where d1, d2, d3 and d4 account for traffic flows corresponding to calls that
fail within the exchange owing to any of the following reasons:
a) all suitable outlets are busy or unavailable;
b) internal congestion;
c) incomplete dialling;
d) invalid destination code;
e) service barring/blocking (as a result of network management
controls, for instance, or the operation of some
supplementary service (e.g. absentee service), or because
the calling/called party is disallowed such service).
The types of calls, viz. system-originating call and system-terminating
calls, result from the operation of some of the supplementary or value-added
services that SPC exchanges offer in addition to conventional telephone service.
In the traffic flow diagram of Figure 4/E.502, system-originating and
system-terminating calls are identified by the aggregate traffic flows C and S
respectively.
4 Basic measurement types
4.1 General
4.1.1 Depending on the activities listed in S 1, a different degree of detail
may be needed.
In order to provide bulk data for each of the above-mentioned traffic
categories, overall measurements can be performed on the totality of subscriber
lines and/or circuits.
Figure 4/E.502 - T0200261-88
Such overall measurements have been taken into account in this
Recommendation only for the traffic items from A to P in Figure 4/E.502, while
they have not been considered for items Q, R, S and T since, with the assumptions
made above, it is possible to achieve the relevant information by taking into
account the relationship between these items and the measured ones. It is
recognized that the overall measurement results might be partitioned
1) Inlet is the point on or within the boundary of the exchange system where a call
attempt arrives or arises.
2) Outlet is the point on or within the boundary of the exchange system to which a call
attempt bearing adequate and valid dialling information would tend to be routed.
Fascicle II.3 - Rec. E.502 PAGE1
to cover various Administrations' needs. As an example, in an international
transit exchange, the traffic data measured on the totality of incoming circuits
should be split into data measured on national incoming circuits and
international incoming circuits, and these in turn could be differentiated
according to the relevant country.
More detailed information on traffic data relevant to the exchange and
surrounding network performance can be provided by means of measurements on
selected sets of circuit groups, subscriber line groups, common channel
signalling links, STPs, auxiliary and control units.
Very detailed traffic data can be obtained by the analysis of call
records.
These call records should be produced by the exchange, containing all data
(e.g. time of occurrence of signalling event, dialled digits, etc.)
characterizing each individual call attempt.
The basic measurement types are given in S 4.2 below.
Their applicability will depend on the function of the exchange (local,
transit, international, etc.)
Manufacturers and Administrations are to note that the list of basic
measurement types is derived from the traffic model given in Figure 4/E.502. It
is not intended that every exchange system should contain all the different
measurement types. The measurement types are exchange- and system-dependent, and
are intended as a guide to the type of measurements required to fulfil various
functions. Measurement types may be combined into a few sets to enable
requirements to be met for specific exchange types, e.g. local. In particular
Administrations may consider that by the use of a few measurement types it is
possible to satisfy the majority of their requirements.
No single measurement type can be assumed to be exclusive to a single user
or to satisfy a single requirement. More than one user may require the same
information presented in different ways at the same time. As an example,
measurement type 22 is required for both network management and traffic
engineering purposes.
4.1.2 Network management considerations
4.1.2.1 Information on network management is contained in the E.410 Series of
Recommendations. Network management requires "real-time" monitoring and
measurement of network status and performance and the ability to take prompt
action to control the flow of traffic when necessary.
4.1.2.2 Performance reports
Performance reports can be provided by the exchange and/or its network
management operations system (OS) in the following ways, as required by the
Administration:
i) automatic data - this data is provided automatically as specified in
the exchange or OS program;
ii) scheduled data - this data is provided according to a schedule
established by the network manager;
iii) demand data - this data is provided only in response to a specific
request by the network manager. In addition to performance data, demand
data includes reference data, such as the number of circuits provided
or available for service, routing information, assigned threshold
values, numbers of installed switching system components, etc.;
iv) exception data - this data is provided when a data count for
calculation exceeds a threshold established by the network manager.
Data reports can be provided for example on a 5-minute, 15-minute or
30-minute basis. The specific interval for any data report will be determined by
the network manager. Historic data relating to the previous two or three periods
(5, 15 or 30-minute) must also be available.
4.1.2.3 In order to obtain information and apply controls which may be
instrumental in reducing exchange congestion, Administration should ensure that
network management terminals and functions should have the highest possible
priority, so that network management operations can continue uninterrupted.
4.1.2.4 Information as to which network management controls, detailed in
Recommendation E.412, are currently activated and whether the controls were
activated by manual or automatic means should be available to all necessary
points (for example, the network management centre, exchange staff).
4.1.3 Traffic engineering
Information on measurements for planning purposes is given in
PAGE14 Fascicle II.3 - Rec. E.502
Recommendation E.500. For further details about requirements on measurement
lengths over the year and the day, data reporting intervals, etc., reference
should be made to that Recommendation.
Fascicle II.3 - Rec. E.502 PAGE1
4.2 Measurements
4.2.1 Overall measurements
Type 1: Overall measurements on originating traffic (A).
Object: Totality of subscriber lines.
Entities:
a) Number of originating seizures;
b) Number of call attempts not routed due to:
i) no dialling (including permanent signal),
ii) incomplete dialling3),
iii) invalid address;
c) Number of call attempts lost due to internal congestion4).
Type 2: Overall measurements on internal traffic (E + F + H)5).
Object: Totality of subscriber lines.
Entities:
a) Number of internal seizures;
b) Number of call attempts lost due to internal congestion;
c) Number of call attempts:
i) with called-party busy,
ii) with called-party free/no answer6),
iii) answered;
iv) line out of order,
v) vacant national number,
vi) transferred subscriber;
d) Number of unsuccessful call attempts due to incomplete dialling5).
Type 3: Overall measurements on originating outgoing traffic (G).
Object: Totality of subscriber lines.
Entities:
a) Number of outgoing seizures;
b) Number of call attempts lost due to internal congestion;
c) Number of call attempts in overflow on the last choice route;
d) Number of successful call attempts getting:
3) Not enough digits to discriminate if internal or outgoing call.
4) When possible, broken down by reason of congestion, e.g. c-1 blocking through the
switching network, c-2 unavailability of common resources, c-3 system faults.
5) Entities may be broken down according to relevant traffic flows.
6) Expiring of time-outs calling-party's abandon.
7) Due to time-out expiring or calling-party's abandon or called-party busy.
PAGE14 Fascicle II.3 - Rec. E.502
i) no answer7 ),
ii) answer or metering pulse(s);
e) Number of unsuccessful call attempts due to incomplete dialling3).
Fascicle II.3 - Rec. E.502 PAGE1
Type 4: Overall measurements on incoming traffic (B).
Object: Totality of incoming circuits and both-way circuits.
Entities:
a) Number of incoming seizures;
b) Number of call attempts not routed due to:
i) incomplete dialling8),
ii) invalid address;
c) Number of call attempts lost due to internal congestion.
Type 5: Overall measurements on incoming terminating traffic (I + J + K)9).
Object: Totality of incoming circuits and both-way circuits.
Entities:
a) Number of incoming terminating seizures;
b) Number of call attempts lost due to internal congestion;
c) Number of successful call attempts:
i) with called-party busy,
ii) with called-party free/not answered,
iii) answered or metering pulse(s);
d) Number of unsuccessful call attempts due to incomplete dialling.
Type 6: Overall measurements on transit traffic (L).
Object: Totality of incoming circuits and both-way circuits.
Entities:
a) Number of incoming transit seizures;
b) Number of call attempts lost due to internal congestion;
c) Number of call attempts in overflow on the last-choice route;
d) Number of successful call attempts obtaining:
i) no answer10).
ii) no answer or metering pulse(s);
e) Number of unsuccessful call attempts due to incomplete dialling10).
Type 7: Overall measurements on system originating traffic (O + P)9).
Object: Exchange system.
Entities:
a) Number of system originating seizures;
b) Number of call attempts lost due to internal congestion;
c) Number of successful call attempts:
i) with called party busy or no free outlet,
ii) with called party free/not answered (for O),
iii) answered.
Type 8: Overall measurements on operator-originating traffic (M + N)11).
Object: Totality of operator board trunks.
Entities:
a) Number of operator originating seizures;
b) Number of unsuccessful call attempts due to:
i) incomplete dialling,
ii) invalid address,
iii) internal congestion;
8) Not enough digits to discriminate if internal or outgoing call.
9) Entities may be broken down according to relevant traffic flows.
10) Expiring of time-out or receiving a release forward.
11) Entities may be broken down according to relevant traffic flows.
PAGE14 Fascicle II.3 - Rec. E.502
c) Number of successful call attempts:
i) with called party busy or no free outlet,
ii) with called party free/not answered (for M),
iii) answered.
4.2.2 Measurement on selectable objects
Type 9: Incoming traffic measurements.
Object: Each incoming circuit group and both-way circuit
group.
Entities:
a) Number of incoming seizures;
b) Traffic volume;
c) Number of call attempts lost due to internal congestion12);
d) Number of circuits in service;
e) Number of circuits out of service.
Type 10: Outgoing traffic measurements.
Object: Each outgoing circuit group and both-way circuit group.
Entities:
a) Number of outgoing seizures;
b) Traffic volume;
c) Number of call attempts in overflow;
d) Number of seizures obtaining answer;
e) Number of circuits in service;
f) Number of circuits out of service;
g) Number of dual seizures (both-way circuits only).
Type 11: Route destination traffic measurements.
Object: For destinations on each outgoing circuit group and both-way
circuit group.
Entities:
a) Number of outgoing seizures;
b) Number of effective call attempts;
c) Traffic volume;
d) Number of call attempts, lost due to congestion on the circuit group;
e) Source (identity of incoming circuit group) - if available.
Type 12: Measurements on subscriber line groups.
Object: Set of lines composing a functional unit.
Entities:
a) Originating traffic volume;
b) Terminating traffic volume;
c) Number of originating seizures;
d) Number of terminating seizures;
12) When possible, broken down by reason of congestion, e.g. c-1 blocking through the
switching network, c-2 unavailability of common resources, c-3 system faults.
Fascicle II.3 - Rec. E.502 PAGE1
e) Number of terminating call attempts.
Type 13: Measurements on auxiliary units13).
Object: Selected groups of auxiliary units.
Entities:
a) Number of seizures;
b) Traffic volume;
c) Numbers of non-serviced call attempts;
d) Number of units in service;
e) Number of units out of service.
4.2.3 Measurements on control unit(s)
Type 14: Measurements on control unit(s).
Object: Control unit(s).
These measurements are highly system-dependent and therefore no specific
recommendations on relevant entities can be made. However, it is essential that
systems have provisions for determining the utilization of control units as
required for dimensioning, planning, and grade of service monitoring of the
exchange.
4.2.4 Measurements on call records14)
Type 15: Traffic dispersion and duration.
Object: Originating (by subscriber, exchange system, operator) and/or
incoming seizures (A + B + C + D).
Entities:
a) Source of inlet (local subscriber, exchange system or incoming/both-way
circuit group);
b) Time of seizure of inlet;
c) Dialled digits;
13) By auxiliary units it is meant multifrequency code (MFC) receivers, tone circuits,
etc.
14) The collection of the totality of call attempts could cause an excessive load for
the SPC system resources, therefore such measurements might be performed on a sampling
basis.
15) Whether the call attempt uses or seeks to use any of the supplementary facilities
of the exchange; if so, the supplementary facility concerned shall be specifically
indicated.
PAGE14 Fascicle II.3 - Rec. E.502
d) Service characteristic of call attempt1 5) for successful call attempt;
e) Identity of exchange outlet;
f) Time of seizure of outlet;
g) Time of occurrence of call attempt at exchange outlet;
h) Time of address-complete signal (if available);
i) Time of answer signal;
j) Time of release of outlet;
k) Time of release of inlet.
Fascicle II.3 - Rec. E.502 PAGE1
Type 16: Quality-of-service assessment.
Object: Originating (by subscriber, exchange system, operator)
and/or incoming seizures (A + B + C + D).
Entities:
a) Source or inlet (local subscriber, exchange system or incoming/both-way
inter-office circuit group);
b) Time of seizures of inlet;
c) Dialled digits.
For unsuccessful call attempt, specify causes of failure:
d) No dialling;
e) Incomplete dialling;
f) Invalid address;
g) No free outlet;
h) Internal congestion;
i) Due to network management action.
For successful call attempt:
j) Order of routing choice (first, second, . . ., last) (when considering
the automatic repeated attempts and/or rerouting);
k) Time of address-complete signal (undifferentiated subscriber free,
subscriber busy, backward congestion) (if available);
l) Result of call attempt (answer, release due to abandon, release due to
congestion).
4.2.5 Delay grade-of-service (GOS) monitoring
Measuring delays on a per call basis could produce severe cost penalties
to the exchange. Since the accuracy requirements from the statistical viewpoint
are not very high, call sampling procedures or test calls are normally sufficient
for GOS monitoring purposes. For this reason these measurement types are listed
separately even if types 16 and 17 should belong to S 4.1 and measurement type 18
to S 4.2.
4.2.5.1 On a per exchange basis
Type 17: Overall delay grade-of-service parameters monitoring.
Object: Totality of subscriber lines.
Entities:
a) Total number of originating seizures;
b) Total number of originating seizures for which the required information
for setting up a through connection is available for processing in the
exchange;
c) Total number of originating seizures for which sufficient address
information has been received, which are addressed to a certain
outgoing circuit group and for which the seizing signal or the
corresponding address information is sent to the subsequent exchange;
d) Total number of originating seizures for which the dial tone delay
exceeds a predetermined threshold value;
e) Seizures already counted in b) for which the through-connection delay
exceeds a predetermined threshold value;
f) Seizures already counted in c) for which the call set-up delay exceeds
a predetermined threshold value.
Type 18: Overall delay grade-of-service parameters monitoring.
Object: Totality of incoming or both-way circuit groups.
Entities:
a) Total number of incoming seizures;
b) Total number of incoming seizures for which the required information
for setting up a through connection is available for processing in the
exchange for a certain circuit group;
c) Total number of incoming seizures for which sufficient address
information has been received, which are addressed to a certain
outgoing circuit group and for which the seizing signal or the
corresponding address information is sent to the subsequent exchange;
d) Total number of incoming seizures for which the incoming response delay
exceeds a predetermined threshold value;
e) Seizures already counted in b) for which the through-connection delay
exceeds a predetermined threshold value;
f) Seizures already counted in c) for which the call set-up delay exceeds
a predetermined threshold value.
4.2.5.2 On per circuit group basis
PAGE14 Fascicle II.3 - Rec. E.502
Type 19: Delay grade-of-service parameters monitoring.
Object: Each incoming or both-way circuit group.
Entities:
a) Total number of incoming seizures;
b) Total number of incoming seizures for which the required information
for setting up a through connection is available for processing in the
exchange for a certain circuit group;
c) Total number of incoming seizures for which sufficient address
information has been received, which are addressed to a certain
outgoing circuit group and for which the seizing signal or the
corresponding address information is sent to the subsequent exchange;
d) Total number of incoming seizures for which the incoming response delay
exceeds a predetermined threshold value;
e) Seizures already counted in b) for which the through-connection delay
exceeds a predetermined threshold value;
f) Seizures already counted in c) for which the call set-up delay exceeds
a predetermined threshold value.
4.2.6 Network performance monitoring
Type 20: Network management.
Object: Total exchange and its major components, e.g.
processor.
Entities:
a) Bids;
b) Incoming call queue length and overflows;
c) Number and percentage of bids encountering switching delays;
d) Percentage of processor capacity available or in use;
e) Cross exchange delay measurements;
f) Switching loss;
g) Counts of calls blocked by automatic load shedding actions.
Type 21: Network management.16)
Object: Common channel signalling system and links.
Entities:
a) Counts of signalling units and percent occupancy of signal links;
b) Counts of outgoing Initial Address Messages (IAMs) and incoming answer
signals (ANC and ANN);
c) Counts of incoming Initial Address Messages (IAMs) and outgoing answer
signals (ANC and ANN);
d) Counts of changeovers;
e) Counts of occurrences and duration of terminal buffer overflow
conditions;
f) Counts of circuit group congestion (CGC), National Network Congestion
(NNC), and/or Switching Equipment Congestion (SEC) indications sent and
received on the signalling link;
g) Counts of calls overflowed or lost due to terminal buffer overflow;
h) Counts of Transfer-Prohibited (TFP) signals sent and received on the
link.
Type 22: Network management.
Object: Each circuit group.
Entities:
a) Bids;
b) Seizures - outgoing and incoming;
c) Answer signals received;
d) Overflows;
e) Traffic carried;
f) Number of circuits made busy to traffic;
g) Transit bids;
h) Incoming transit seizures;
16) Although measurement type 21 is identified as being for network management, it is
also required for traffic engineering purposes.
Fascicle II.3 - Rec. E.502 PAGE1
i) Counts of calls affected by network management control, by type of
control.
Type 23: Network management.
Object: Destinations.
Entities:
a) Bids;
b) Seizures;
c) Answer signals received;
d) Overflows;
e) Counts of calls affected by network management controls, by type of
control (Note - This includes code block and call gap controls).
4.2.7 Measurement of the performance of common channel signalling systems
Measurement Type 21 (see S 4.2.6) is required. Other measurement types are
for further study.
4.2.8 Measurement of the integrated services digital network and its services
For further study.
5 Related Recommendations
The use of the analysed results will be dependent on the procedures in
each Administration. The list of Recommendations below are those currently
existing and covering many operational aspects. They are offered only as a guide
rather than a comprehensive and complete set.
- Recommendation E.500 defines the traffic intensity measurement
principles;
- Recommendation E.175 defines the network model for planning purposes;
- E.410 Series of Recommendations provide information for network
management;
- E.420 Series of Recommendations describe checking the quality of the
international telephone service;
- Recommendation E.506 defines the forecasting methods for international
traffic;
- Recommendation E.543 defines the grade of service in digital
international telephone exchanges;
- Recommendation E.503 defines the traffic measurement data analysis;
- Recommendation E.504 defines the traffic measurement administration;
- the O Series of Recomendations outline specifications of measuring
equipment;
- the M Series of Recommendations detail many maintenance aspects of
international carrier and circuits;
- The Q Series of Recommendations cover all aspects relating to common
channel signalling.
- Recommendation Q.544 deals with exchange measurements.
ANNEX A
(to Recommendation E.502)
The purpose of this Annex is to identify the measurements to be made at
exchanges and the criteria needed to satisfy the basic measurement requirements,
and is produced to assist the exchange designers to ensure that these
measurements can be made.
Considering that an SPC digital exchange is mainly composed of software
with few physical entities which can be identified as specific measurement
points, it is not possible to identify exactly where measurements should be
taken. However, the basic measurement types given in S 4.2 require that it be
possible to differentiate between events occurring:
i) from a customer/previous exchange node, arriving at an exchange.
ii) from an exchange to another exchange node/customer.
iii) within an exchange.
In the three segments indicated above it is necessary to have the ability
to record the entities independently in each segment, as well as being able to
associate entities between segments.
The entities recorded are:
- bids;
- seizures;
- effective calls;
- congested bids;
PAGE14 Fascicle II.3 - Rec. E.502
- traffic volume.
An exchange should categorize failed call attempts according to the reason
for the failure. However, the information available to the exchange for this
purpose may depend on the signalling system used and the function and position of
the exchange in the network relative to the failed call attempts.
It should be noted that measurement type 15 is a call record which has to
be generated wholly within an exchange system. Also, measurement types 20, 21, 22
and 23 are specific to network management requiring slightly different criteria.
It shall be possible for any of the basic measurement types to be
amalgamated to form a unique measurement program to meet an Administration's
requirements. It shall also be possible to output measurement information to more
than one user. As an example, measurements may be in progress continuously for
traffic engineering purposes and, at a particular time (say for one hour),
measurements of the same type may be required for maintenance purposes. The
output or recording of these two measurements must not interfere with each other
or with any other measurements being made at the same time, e.g. for network
management.
Fascicle II.3 - Rec. E.502 PAGE1
