As with performance management, the first step toward appropriate accounting management is to measure utilization of all important network resources. Analysis of the results provides insight into current usage patterns, and usage quotas can be set at this point. Some correction, of course, will be required to reach optimal access practices. From this point, ongoing measurement of resource use can yield billing information, as well as information used to assess continued fair and optimal resource utilization. Because faults can cause downtime or unacceptable network degradation, fault management is perhaps the most widely implemented of the ISO network management elements.
Fault management involves first determining symptoms and isolating the problem.
Then the problem is fixed, and the solution is tested on all important subsystems. Finally, the detection and resolution of the problem is recorded. A security management subsystem, for example, can monitor users logging on to a network resource, refusing access to those who enter inappropriate access codes. Security management subsystems work by partitioning network resources into authorized and unauthorized areas. For some users, access to any network resource is inappropriate, mostly because such users are usually company outsiders.