Network Connectivity

Abstract

It is essential that users see the network as transparent as possible, yet ensuring high level of confidentiality and security. As in many similar cases, all the network resources can be considered virtual objects, hence ensuring the required transparency. In practice, there are two ways to implement transparency: either by server’s OS, for instance, using the built-in support by MS Windows 2000, or following the DCE concepts rely on an enterprise NOS such as Novell NetWare. The Open Software Foundation (OSF) Distributed Computing Environment (DCE) proposal represents a comprehensive integrated set of tools and services, which support creation, use, and maintenance of distributed applications in a heterogeneous computing environment. Yet, the full acceptance of OSF DCE is still uncertain. Sun has introduced its own Open Network Computing (ONC) as an alternative to the OSF DCE. Neither Novell nor IBM has fully endorsed DCE. Microsoft has supported only part of DCE. Still, it is important to review the OSI X.500, OSF DCE, and C2 network standards in order to understand the DCE: X.500 is the industry standard for global network directory, based on replicated distributed database, designed to run under the OSI communication protocol. X.500 network directory follows Object Orientation. Each object in the directory belongs to a member class. Any client or server derives its attributes using appropriate API from the class hierarchy. The communication among clients and servers makes use of directory agents, DUA and DSA, the user and server agents respectively. They require appropriate protocols, DAP and DSP, respectively. In addition to X.500, TCP/IP and IPX/SPX can coexist as important proprietary standard alternatives, still in wide use by enterprise networks. Periodically, time agents synchronise clocks within the systems to maintain and handle the unique time across the network. Similarly, DCE makes use of time clerks.

There is always a chance that things will go wrong, and do go wrong moreover at the worst possible moment’.

Murphy’s law