home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Internet Standards
/
CD2.mdf
/
ccitt
/
1992
/
e
/
e410.asc
< prev
next >
Wrap
Text File
|
1991-12-30
|
14KB
|
214 lines
All drawings appearing in this Recommendation have been done in Autocad.
Recommendation E.410
INTERNATIONAL NETWORK MANAGEMENT - GENERAL INFORMATION
1 Introduction
The demand for international telephone service continues to increase
substantially. This increasing demand has been met by advances in both technology
and operational techniques. The growth of traffic has also required the
development of larger transmission systems and exchanges to provide the capacity
to meet the required grade of service. With the continued growth of the
international automatic service, direct supervision and control over traffic has
decreased since operators are no longer involved in establishing most calls.
In addition to the above, the introduction of larger digital transmission
and switching systems, along with common channel signalling, has resulted in an
international telephone network which is highly interconnected and interactive,
and which has become increasingly vulnerable to overload and congestion. This
overload and congestion can occur with little or no advance warning.
A number of events may arise which can have a serious effect on the
international telephone service. Among these events are:
- failures of international or national transmission systems;
- failures of international or national exchanges;
- planned outages of transmission systems and exchanges;
- abnormal increases in traffic demand. The events which give rise to
such traffic demand may be foreseen (e.g., national or religious
holidays, international sporting events) or unforeseen (e.g., natural
disasters, political crises);
- focussed overloads, and in particular, mass-calling;
- difficulties in meeting the requirements of international traffic
resulting (for example) from delays in the provision of additional
circuits or equipment;
- congestion in connected networks.
These events can lead to congestion which, if uncontrolled, may spread and
thus seriously degrade the service in other parts of the international network.
Considerable benefits can be derived for the international network as a whole if
prompt action is taken to control the effect on service of such events.
In addition, as the telephone network migrates toward ISDN, interworking
with other networks will develop. With interworking, failure or congestion in one
network, or in the interface between networks, can have an adverse impact on the
performance of the connected network(s).
The above considerations have led to the development of "international
network management", which encompasses all the activities necessary to reduce the
effect on service of any situation affecting unfavourably the international
telephone network, and in the future, the ISDN.
Note - Much of the guidance on international network management may be
applicable in national networks.
2 Definition of international network management
international network management is the function of supervising the
international network and taking action when necessary to control the flow of
traffic.
Network management requires real-time monitoring and measurement of
current network status and performance, and the ability to take prompt action to
control the flow of traffic.
3 Objective of network management
The objective of network management is to enable as many calls as possible
to be successfully completed. This objective is met by maximizing the use of all
available equipment and facilities in any situation through the application of
the principles given below.
4 Principles of international network management
4.1 Utilize all available circuits
There are periods when, due to changing traffic patterns, the demand for
service cannot be met by the available circuits in the normal routing. At the
same time, many circuits to other locations may be idle due to differences in
calling patterns caused by time zones, local calling habits, or busy season
variations. After negotiation and agreement amongst the Administrations affected,
some or all of the unusually heavy traffic can be redirected to this idle
capacity for completion.
Fascicle II.3 - Rec. E.410 PAGE1
4.2 Keep all available circuits filled with traffic which has a high
probability of resulting in effective calls
The telephone network is generally circuit-limited; therefore the number
of simultaneous effective calls is strongly influenced by the number of available
circuits. However, ineffective calls can occupy circuit capacity which would
otherwise be available for effective calls. Therefore identifying those call
attempts which are likely to be ineffective because of a situation in the network
(e.g., a failure), and reducing them as close to their source as possible, will
allow circuit capacity to be available for call attempts which have a higher
probability of being effective.
4.3 When all available circuits are in use, give priority to calls requiring a
minimum number of circuits to form a connection
When telephone networks are designed using automatic alternate routing of
calls, efficient operation occurs when traffic loads are at or below engineered
values. However, as traffic loads increase above the engineered value, the
ability of the network to carry effective calls decreases since an increased
number of calls require two or more circuits to form a connection. Such calls
increase the possibility of one multi-link call blocking several potential calls.
Thus automatic alternate routing should be restricted to give preference
to direct routed traffic during periods of abnormally high demand.
4.4 Inhibit switching congestion and prevent its spread
A large increase in switching attempts can result in switching congestion
when the switching capacity of an exchange is exceeded. If the switching
congestion is left uncontrolled, it can spread to connected exchanges or networks
and cause a further degradation of network performance. Controls should be
applied which inhibit switching congestion by removing attempts from the
congested exchange which have a low chance of resulting in a succesful call.
Note - Network management assumes that the network is adequately
engineered to meet the normal levels of traffic, the requirement for which is
described in Recommendations E.171, E.510, E.520, E.522, E.540 and E.541.
5 Benefits derived from international network management
Among the benefits to be derived from international network management
are:
5.1 Increased revenue which is derived from an increase in successful calls.
5.2 Improved service to the customer. This can lead, in turn, to:
- improved customer relations;
- stimulation of customer calling rate;
- increased customer acceptance of new services.
5.3 More efficient use of the network. This can result in:
- an increased return on the capital invested in the network;
- an improvement in the ratio of effective to ineffective calls.
5.4 Greater awareness of the actual status and performance of the network.
Such awareness can lead to:
- a basis by which network management and maintenance priorities can be
established;
- improved network planning information;
- improved information on which future capital investment in the network
can be decided;
- improved public relations.
5.5 Protection of revenue and important services, particularly during severe
network situations.
6 Network management functions
Network management encompasses all of the activities necessary to identify
conditions which may adversely affect network performance and service to the
customer, and the application of network controls to minimize their impact. This
includes the following functions:
a) monitoring the status and performance of the network on a real-time
basis, which includes collecting and analyzing relevant data;
b) detecting abnormal network conditions;
c) investigating and identifying the reasons for abnormal network
conditions;
d) initiating corrective action and/or control;
e) cooperating and coordinating actions with other network management
centres, both domestic and international, on matters concerned with
international network management and service restoration;
PAGE2 Fascicle II.3 - Rec. E.410
f) cooperating and coordinating with other work areas (e.g., maintenance,
operator services or planning) on matters which affect service;
g) issuing reports of abnormal network situations, actions taken and
results obtained to higher authority and other involved departments and
Administrations, as required;
h) providing advance planning for known or predictable network situations.
7 Cooperation and coordination
Effective network management depends on the prompt availability of
information indicating when and where a problem is occurring, and a trained group
working in cooperation with all parts of the telecommunications organization.
Just as there is a need for coordination in planning and building the network,
there also is a need for coordination in managing it. The network is such that
equipment malfunctions or overloads frequently produce unacceptable performance
at a distance from the physical location of the problem. Therefore, those who
monitor and manage the network, both nationally and internationally, must
cooperate to ensure satisfactory service.
Network management is highly technical in nature, and depends on the skill
and creativity of those who share an understanding of network management
philosophy, objectives, terminology, tools and techniques. These items are
specified in Recommendations E.410 through E.414, and provide a basis for the
cooperation and coordination which are a vital part of network management.
8 Further Recommendations on network management
8.1 Recommendation E.411 provides operational guidance for network management
including:
- status and performance parameters;
- expansive and protective traffic controls;
- criteria for application of controls.
8.2 Recommendation E.412 provides information on network management controls:
- traffic to be controlled;
- exchange controls;
- automatic controls;
- status of controls;
- operator controls.
8.3 Recommendation E.413 provides guidance on planning for events such as:
- peak calling days;
- failures of transmission systems;
- failures of exchanges;
- failures of common channel signalling systems;
- mass-calling situations;
- disasters;
- introduction of new services.
8.4 Recommendation E.414 provides guidance on the functional elements of a
network management organization which need to be identified internationally as
contact points. These comprise:
- planning and liaison;
- implementation and control;
- development.
8.5 It is emphasized that it is not necessary to meet the full scope of these
Recommendations to achieve some benefit from the application of network
management, particularly when getting started. However, the Recommendations do
provide detailed information over a wide range of techniques, some of which can
be implemented readily, whilst others may require considerable planning and
design effort. Additional information may also be found in the handbook on
Quality of service, network management and maintenance [1].
Reference
[1] CCITT Manual Quality of service, network management and maintenance, ITU,
Geneva, 1984.
Fascicle II.3 - Rec. E.410 PAGE1