etwork management systems have become an increasingly important part of today's computer networks. As the complexity of networks increases, so have the requirements of the systems managing these networks. These requirements include providing standard interfaces for information sharing among management systems, having extensibility for handling change quickly, and providing a means to minage large networks.One possible approach to handle these requirements is to design an open, standards-based, extensible, and distributed network management system using CORBA. The CORBA interface to the system facilitates easy communication with other systems. Its extensible nature allows the system to grow in future. Finally, CORBA's distributed capabilities make it possible to manage large numbers of nerwork devices in a scalable manner.ProSphere is a CORBA-based [1,8] distributed network management system for General DataComm's (GDC) Asynchronous Transfer Mode (ATM) product line. This product line includes network edge and backbone ATM switches, which are deployed in many telecommunications carriers and private networks worldwide.The ProSphere architecture consists of a set of CORBA servers, which provide Network Management Services; and Java client applications that present information from the servers in graphical interfaces. The architecture is extensible, allowing new kinds of network devices to be supported with little or no change to existing software. The architecture is open, allowing end-user (customer) integration through CORBA Interface Definition Language (IDL) interfaces. The architecture is portable-Java clients can run from any type oi host machine or Web browser. Finally, the ProSphere architecture is distributed in that the system comfxments (clients, servers, and objects) can reside in separate processes and hosts. We describe the ProSphere architecture here and show how it benefits from the use of CORBA. | i Background

ORBA onnection KRISHNAN SEETHARAMAN^Î n the early days of computing, computers operated independently of one another with no communication between them. The hardware and the system software were proprietary and supplied by a single vendor. The software applications were usually custom-developed for specific purposes. Data sharing between systems was minimal and done the oldfashioned way-by physically transporting tapes or other storage media from one system to the other. The next step was to connect the computers and devices in a network using proprietary protocols for data communications. This was followed by the development of standard protocols and open systems. The era of open systems also led to system integration in which the customers could choose various hardware components from different vendors and integrate them to create a custom configuration suiting their computing needs and cost requirements. Hardware itself was designed and built using off-the-shelf components-microprocessors, memory chips, and other such basic building blocks.