Network management can range from a solitary network consultant monitoring
network activity with a simple protocol analyzer, to the use of a distributed
database with auto-polling of network devices. Network management could also
include the use of high end workstations generating real time graphical views
of network topology changes and traffic. In general, network management is a
service that employs a variety of tools, applications, and devices to assist
network managers in monitoring and maintaining networks.
Most network
management architectures use the same basic structure and set of relationships.
End stations, or managed devices, such as computer systems and other network
devices, run software that enables them to send alerts when they recognize
problems. An example would be when one or more user determined thresholds are
exceeded.
Upon receiving these alerts, management entities are
programmed to react by executing one action, or a group of actions. This would
include operator notification, event logging, system shutdown, or automatic
attempts at system repair.
Management entities can also poll end
stations to check the values of certain variables. Polling can be automatic or
user initiated, but agents in the managed devices respond to all polls. Agents
are software modules that first compile information about the managed devices
in which they reside, and then store this information in a management database.
Finally agents provide information proactively or reactively to management
entities within network management systems (NMSs) via a network management
protocol. Well known network management protocols include the Simple Network
Management Protocol (SNMP) and Common Management Information Protocol (CMIP).
Management proxies are entities that provide management information on behalf
of other entities. Figure
depicts a common
network management architecture.
The International Organization for
Standardization (ISO) has contributed a great deal to network standardization.
The organization's network management model is the primary means for
understanding the major functions of NMSs. This model consists of five
conceptual areas:

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Performance management – The goal is to measure and provide various
aspects of network performance in order to maintain internetwork performance at
an acceptable level. Examples of performance variables include network
throughput, user response times, and line utilization.
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Configuration management – The goal is to monitor network and system
configuration information so that the effects on network operation of various
versions of hardware and software elements can be tracked and managed.
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Accounting management – The goal is to measure network-utilization
parameters so that individual or group use of the network can be regulated
appropriately. Such regulation minimizes network problems because network
resources can be apportioned based on resource capacities, and maximizes the
fairness of network access among users.
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Fault management – The goal is to detect, log, notify users of, and
if possible, automatically fix network problems to keep the network running
effectively. Because faults can cause downtime or unacceptable network
degradation, fault management is perhaps the most widely implemented of the ISO
network management elements.
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Security management – The goal is to control access to network
resources to prevent the network from being sabotaged or unintentionally
brought down, and to prevent sensitive information from being accessed by
unauthorized users. A security management subsystem can monitor users logging
on to a network resource and deny access to those who enter inappropriate
access codes.