Local Area Networks: Software

Transcription

1 School of Business Eastern Illinois University Local Area Networks: Software (Week 8, Thursday 3/1/2007) Abdou Illia, Spring 2007 Learning Objectives 2 Identify main functions of operating systems Describe basic features of common Network operating systems Explain main features of Network Operating Systems: Remote Access service Directory service Software Disk Fault-tolerance Clustering Network Load Balancing Software and Support Systems 3 Workstation Operating System on workstations Network Operating System on servers - Workstation Operating System - Client application programs - Network Operating System -Utility programs - Application programs: - Word processor - Spreadsheets - Accounting 1

2 Operating Systems Program initially loaded into computer memory User Application program Operating system Hardware 4 Interfaces Manages hardware & software resources: Disks, memory, processors, application programs, etc. Key function: Ensure that each application gets necessary resources Suppose that a Web browser and a word processor are executed at the same time. Which resources the two applications might need to access to? Operating Systems 5 A special program for managing hardware and software resources that ensure each application program gets necessary resources Common OS functions: Multitasking 6 Multi-tasking (multiple prog./tasks running at the same time) OS allocates small amount of the time to each prog./task Jumps quickly from one prog./task to another. 2

3 Common OS functions: Virtual Memory, Security 7 Virtual memory management: OS feature that allows loading programs even if RAM is limited Needs enough HD space Handling: Input operations from attached devices (e.g. disks) Output operations to attached devices (e.g. disks, printers) Providing resource security E.g. Directory & files security to provide protection from unscrupulous users Network Operating Systems (NOS) 8 OS designed for Servers use (also called SOS) Same functions as Workstation OS + - Ability to manage users and other resources common to the LAN - Providing key network services Common resources managed by NOS Server(s) Printer(s) Network interconnection(s) Users Group policies to be applied to users and computers Network Operating Systems (NOS) 9 3

4 Summary Questions 10 Your organization has 12 employees, each with his or her own stand-alone PC running Windows 98. Each computer has a 10 Mbps NIC that could work with coaxial cable or twisted pair (see next slide) a) List all the additional hardware and software you would have to buy to install a 100BaseTX LAN. Be very sure that you list all the things the organization will have to buy. The organization wishes to use electronic mail, word processing, file sharing, and print sharing with four existing printers fed with parallel ports. b) How many ports should the hub or switch have? Explain. Dual-transmission NIC 11 RJ45 connector BNC Thinnet connector Ethernet standards 12 4

5 Remote Access Service 13 Remote Access Client Software Remote Access Server Remote Access Server Remote Access Service 14 User dials into a remote access server Server authenticates the user (user must prove identity) If authenticated, user may use network resources Client PC needs RAS client software Internal Server LAN RAS RAS Client Software Dial-Up Telephone Line Dial-In Client Directory Service 15 Needed in large networks with dozens or hundreds of servers Directory database contains info about all network resources Usually provides: Single login and Resource lookup. Directory Database 5

6 Disk Fault-tolerance 16 Disk Fault-tolerance could be achieved through Hardware RAID (Redundant Array of Independent Disks) Software RAID File Data spread across these disks Last disk contains ECC* data for disks 1-4 Clustering Technique for providing uninterrupted service (even in case of hardware/software failure) Combining two or more servers into one virtual server 17 Services installed on external storage Users connect to the virtual server ( in illustration) One of the clustered servers provides the service at a time Mac client Windows client Load Balancing 18 Load balancing = Distributing the load among multiple servers No External disk containing services to be provided Multiple independent servers configured to participate in the load balancing Same service with the same content on each server Users connect to the virtual server ( in illustration) Users requests are redirected to one server at a time so that the load is distributed among all the servers Virtual server Webservice Webservice Webservice Webservice Webservice 6

7 Current Network Operating Systems 19 Novell NetWare SOS Once dominant, but market share has shrunk Excellent file service Excellent directory service called NetWare Directory Services (NDS), now edirectory. NetWare strong directory service is convincing many medium firms to continue using NetWare. Version Comment NetWare 286 Released in 1986, Uses IPX/SPX NetWare 3.x 4.x Included clustering, NDS NetWare 5.x 6.x Switch to TCP/IP, Apache webserver Novell Open Enpterprise Server Released in 2005, Linux platform Current Network Operating Systems 20 Microsoft Windows Server Operating Systems Microsoft Windows NT Server Microsoft Windows Server 2000: Windows 2000 Server Windows 2000 Advanced Server Windows 2000 DataCenter Server Microsoft Windows Server 2003 Windows Server 2003 Standard Edition Windows Server 2003 Enterprise Edition Windows Server 2003 DataCenter Edition Windows Server 2003 Compute Cluster Edition Current Network Operating Systems 21 Microsoft Windows Server Operating Systems Easy to install, learn, and use because resembles desktop Windows Is dominant for small business and small department servers Windows Server OS has serious reliability problems: Tend to crash more frequently than other OS Windows 2003 Server versions promise to improve reliability, but: A path called Windows Server 2003 R2 released in

8 Current Network Operating Systems 22 UNIX Extremely reliable (speed, stability) UNIX server OS dominate the enterprise server market Many versions of UNIX exist UNIX: Must with the Single UNIX Specification Free UNIX-Like versions initiated by GNU project Different management utilities Current Network Operating Systems 23 LINUX Version of UNIX (Free UNIX-Like) Runs on Intel PCs; low cost Available free But usually pay around $50 to $150 for packaged version Reliable like other UNIX versions Open Source: Many people are developing tools to add to the LINUX core Current Network Operating Systems 24 Mac Server OS "Classic" Mac OS ( ) User-friendly, completely graphical operating system Mac OS X Workstation and Server (2001-present) based on the BSD* implementation of UNIX Mac OS X versions Date Released Mac OS X v10.0 Cheetah March 2001 Mac OS X v10.3 Panther October 2003 Mac OS X v10.4 Tiger April 2005 Mac OS X v10.5 Leopard Upcoming in 2007 * Berkeley Software Distribution or Berkeley UNIX 8

9 Summary Questions In remote access service, what kind of software does the remote PC need? What is needed on the LAN side? 2. What kind of services are provided by Directory servers? What is disk fault-tolerance? What is the difference between Clustering and Network Load Balancing? 3. What is the difference between a Workstation Operating System and a Network Operating System? 4. Name two Workstation Operating System and two NOS. 5. Name one important strength of Novell NetWare NOS that is convincing many firm to continue using it. 6. What is virtual memory? 9