garding network performance. It maintains and enforces network security, such as link encryption and issuance and use of passwords. It gathers and files data on network usage. It performs a configuration management function. It also performs an administrative management function. 21.2 THE BIGGER PICTURE Many seem to view network management as a manager of data circuits only. There is a much bigger world out there. Numerous enterprise and government networks serve for the switching and transport of multimedia communications. The underlying network will direct (switch) and transport voice, data, and image traffic. Each will have a traffic profile notably differing from the other. Nevertheless, they should be managed as an entity. If Fundamentals of Telecommunications, Second Edition, by Roger L. Freeman ISBN 0-471-71045-8 Copyright © 2005 by Roger L. Freeman NETWORK MANAGEMENT for no other reason, it is more cost-effective to treat the whole rather than piecemeal by its parts. There is a tendency in the enterprise scene to separate voice telephony, calling it telecommunications, and another world, that of data communications. Perhaps that is why network management seems to often operate on two separate planes. One is data and very sophisticated, and the other is voice, which may have no management facilities at all. This next section treats network management as a whole consisting of its multimedia parts: voice, image, and data, which includes facsimile, telemetry, and CAD/CAM. 21.3 TRADITIONAL BREAKOUT BY TASKS There are five tasks traditionally involved with network management: Fault management Configuration management Performance management Security management Accounting management 21.3.1 Fault Management This is a facility that provides information on the status of the network and subnetworks. The "information on the status" should not only display faults, meaning failures, and their location, but should also provide information on deteriorated performance. One cause of deteriorated performance is congestion. T