Evolution of PC_LANS and Networks Prithvi N. Rao Carnegie Mellon University

Objectives Describe the evolution of corporate management structures. List the characteristics of a centralized network system. Recognize the challenges of building an enterprise-wide network. List some of the critical issues facing network managers.

Introduction Communication is fundamental to organizational effectiveness. Management structure determines structural requirements for communication. Evolution from function oriented steep hierarchies to flatter process focused structures. Functional structures require hierarchical communication based on centralized architectures. Process structures require more de-centralized communication.

Steep Functional Hierarchy Manufacturing Sales Executive Management Senior Management Middle Management Staff Line

Flat Process Orientation Executive Management Project Leader Team Members: Sales/Marketing/Mfg./Operations/Customer Svc.

Introduction Effective organizations must have a communication system that links all of its resources: people, information and tools. Evolution of roles increases the importance of communications. Creates new demands on systems for supporting complex organizations and communications requirements. Computers link people, information and tools. Meet flat process structural standard. Vendors must communicate with each other. Software tool compatibility is important.

Evolution Networks facilitate effective communicate using computers. Information on networked computers must be accessible. Vendors work closely with customers and each other to ensure that an open communications environment is maintained. Open environment facilitates the use of heterogeneous hardware and software infrastructures as well as various types of cabling. Network operating systems facilitate sharing. Database Systems, Electronic mail systems facilitate sharing.

Computer System Evolution Move towards smaller, faster, cheaper hardware. PCs are getting cheaper and faster Memory speed is increasing. Applications are demanding more resources. Audio, Video, Speech…. Operating systems have also evolved. Operating systems cannot keep up with hardware advances. Result over 20 years is inversion of cost/performance. Vacuum tube -> high cost, low performance. VLSI -> low cost, high performance.

Computer System Evolution Evolution of computer systems occurred in distinct phases PhaseType of MIS Environment Equipment Justification Phase 1Centralized Mainframes Organizational- wide Functional Automation Phase 2Distributed/Depa rtmental PC’s/Minis Personal/Departm ental Effectiveness Phase 3Distributed/Enter prise Networks Workgroup Productivity

Mainframe Architecture Mainframe based network systems were centralized. Tightly controlled of computer and shared peripherals. Terminal devices connected (dumb terminals). Star networking design. Few computer to computer integration requirements.

Mainframe Architecture Mainframe Channel-to-Channel Or Link Attached FEP Channel-to-Channel Or Link Attached Dumb Terminals

Distributed Networks First networks enabled simple file and resource sharing (printers). PC networks used originally to support communication at departmental level. PC networks contrasted mainframe phase: Local area network Shared resources: data, programs, peripherals Distributed processing Intelligent workstations Bus or ring network topology

Network Topology: Token Ring Server Shared Resource (printers) PC Token Ring

Network Topology: Ethernet terminator WS Ethernet Thinnet: 185 meters (~600 feet) Thicknet: 500 meters (~1700 feet)