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Local Area Networks: Software
© Abdou Illia, Spring 2007
School of BusinessEastern Illinois University
(Week 8, Thursday 3/1/2007)
2Learning Objectives
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
3Software and Support Systems
- Workstation Operating System- Client application programs
- Network Operating System-Utility programs- Application programs:
- Word processor- Spreadsheets- Accounting
• Workstation Operating System on workstations• Network Operating System on servers
4Operating Systems
Program initially loaded into computer memory
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 ?
User
Application program
Operating system
Hardware
Interfaces
5Operating Systems
A special program for managing hardware and software resources that ensure each application program gets necessary resources
6Common OS functions: Multitasking
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.
7Common OS functions: Virtual Memory,Security 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
8Network Operating Systems (NOS)
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
9Network Operating Systems (NOS)
10Summary Questions
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.
11Dual-transmission NIC
BNC “Thinnet” connector
RJ45 connector
12Ethernet standards
13Remote Access Service
Remote Access ServerRemote Access Server
Remote Access Client
Software
14Remote Access Service
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
LAN
InternalServer
RAS
Dial-InClient
Dial-UpTelephone
Line
RASClient
Software
15Directory Service
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
16Disk Fault-tolerance
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
17Clustering Technique for providing uninterrupted service (even in case of
hardware/software failure)
Combining two or more servers into one virtual server
Services installed on external storage
Users connect to the virtual server (167.10.11.5 in illustration)
One of the clustered servers provides the service at a time
Server Server
HubHub
Virtual server167.10.11.5
SharedFolder- Web service- Email service
Win 2000 Pro WorkstationWin 98 Workstation
External Disk
Mac client Windows client
18Load Balancing
Hub
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 (167.10.11.5 in illustration)
Users’ requests are redirected to one server at a time so that the load is distributed among all the servers
Server
Webservice
Server
Webservice
Server
Webservice
Server
Webservice
Server
Webservice
Virtual server167.10.11.5
19Current Network Operating Systems
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.
NetWare 286 Released in 1986, Uses IPX/SPXVersion Comment
NetWare 3.x – 4.x Included clustering, NDSNetWare 5.x – 6.x Switch to TCP/IP, Apache webserver
Novell Open Enpterprise Server Released in 2005, Linux platform
20Current Network Operating Systems
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
21Current Network Operating Systems
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 2005
22Current Network Operating Systems
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
23Current Network Operating Systems
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
24Current Network Operating Systems
Mac Server OS– "Classic" Mac OS (1984-2001)
User-friendly, completely graphical operating system – Mac OS X Workstation and Server (2001-present)
based on the BSD* implementation of UNIX
* Berkeley Software Distribution or Berkeley UNIX
Mac OS X versions Date ReleasedMac OS X v10.0 “Cheetah” March 2001Mac OS X v10.3 “Panther” October 2003Mac OS X v10.4 “Tiger” April 2005
Mac OS X v10.5 “Leopard” Upcoming in 2007
25Summary Questions
1. 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?