Operating Systems on the Network

• Approaches to managing network resources– Peer-to-peer model

• All the computers on the LAN have the same authority and each can act as a server to the other computers

– Client/server model• One or more computers control the resources for all

computers on the network• These servers require a network operating system (NOS)• Also called the domain model

Example of a Peer-to-Peer Network

Example of a Network Operating System (NOS)

Operating Systems for the Client

• On a LAN, each PC must have an operating system that is capable of interfacing with a network interface card and the resources available on the network

• Options for a personal computer OS– Windows 9x (most popular)– Windows NT

• Windows NT Workstation• Windows NT Server

– Linux

Windows 9x

• Low-level; primarily used for personal computers• Backward compatible with DOS,

Windows 3.x, and legacy hardware devices• Supports network access• Can be used in a peer-to-peer or client/server

network

Windows 9x

Windows 9x

Windows NT Workstation

• Works well as a stand-alone OS or as an OS on a PC that is part of a peer-to-peer network or client/server network

• Like Windows 2000, does not support legacy software or hardware; expects hardware and software to follow the rules of relating to a true 32-bit OS

The Windows NT Desktop

Linux

• A scaled-down version of UNIX• Small enough to run on a 486 computer, but has

network capabilities similar to a full-fledged commercial version of UNIX

• Appropriate for – A small company environment with low-volume traffic

for internet services– Internet-in-a-box devices– A web server or proxy server for a LAN

Largest Drawbacks to Using Linux

• Lack of support and standards

• Lack of application software written for it

• Lack of experienced technical people

An Operating System

The Shell and the Kernel

• Operating system kernel– Core portion of the OS that loads applications

and manages files, memory, and other resources

• Operating system shell– Responsible for providing an interface for

users to enter OS commands

Different Approaches to a Shell

• Windows– Uses a GUI shell as the default shell

• Linux and UNIX– Use a command-line shell as the default shell,

and a GUI as an add-on feature

A Windows Shell

A Linux Shell

Network Operating Systems

• Reside on the controlling computer in the network

• Control software, data, and devices a user can access

Criteria to Consider When Selecting a NOC

• Reliability• Performance• Adaptability• Ease of use and ease of installation• Affordability• Security• Scalability

Popular Network Operating Systems

• Windows NT Server and Windows NT Enterprise Server

• Windows 2000

• Netware by Novell

• UNIX and Linux

Windows NT Server and Windows NT Enterprise Server

• Designed to create and support a client/server network for a LAN called a domain

• One computer is designated the primary domain controller (PDC)– Server that controls a database of user accounts,

group accounts, and computer accounts– Database is also called a directory database or

security accounts manager (SAM) database

• Backup domain controller (BDC)– A server that contains a read-only copy of the domain

database

A Windows NT Domain

Windows 2000

• Includes four operating systems– Windows 2000 Professional– Windows 2000 Server– Windows 2000 Advanced Server– Windows 2000 Datacenter Server

Netware by Novell

• A popular NOS that can provide fast file and database access

• Uses a suite of protocols called IPX/SPX, which generally correspond to the TCP/IP protocols

UNIX

• Provides services over the Internet; can also support a LAN as a file and database server

• Used by 48% of today’s web servers on the Internet

• The accepted mainstay for the firewall market• TCP/IP and Java were developed in a UNIX

environment• Several hardware manufacturers offer their own

version of UNIX

Advantages and Disadvantages of UNIX

• Advantages – Highly reliable– Highly scalable– High performing– Powerful

• Disadvantages– Not easy to learn– Requires experienced, well-trained administrative and

technical staff

Linux

• Originally an OS for a personal computer; fast becoming a viable option as a NOS

• Performs at about 40% of the speed of Windows NT Server

Network Services

• Wide range of possible network services

• Two primary services are printers and directory shares

• Others services include:– Groupware applications– Mail packages– Shared whiteboard applications– Web servers

Installing, Removing, and Configuring Network Services

• Driver or network itself provides network service • Most NOSs have administrative tool for installing

and removing network services• Control network services in two ways:

– Through global services administrative tool– Through console plug-in related to specific

service– Add new tools under the Microsoft

Management Console (MMC)

Network Bindings

• Process of linking network components from various levels of network architecture to ensure communication between them– Associates upper-layer services and protocols

to lower-layer network adapter drivers

• Bind the most frequently used protocol, service, or adapter first to speed network connections

Network Printing

• Redirector intercepts printer requests and forwards them to print servers or network-connected printers

• Network printing involves installing printer– Some clients require local printer drivers– Others access printer drivers from print server

• New local printer points to print share

Printer Management

• Manage printers from local direct access or through network printer share; – Windows 2000/2003/XP lets you manage

printers through Web browser• Printer management includes:

– Granting and restricting user access to printers– Monitoring print queue– Limiting access by time frame, department, or

priority– Updating local and remote printer drivers– Maintaining printers; managing printers

remotely

Sharing Fax Modems

• Feature not usually default component in NOS– Use third-party add-on product

• Once drivers are installed, manage and administer fax shares like printer shares

Network Directory Shares

• Let clients access and interact with storage devices on network

• Three ways to access shared directory:– Map unused local drive letter to directory share– Use UNC name to reference directory share– Select directory share from list of available shares

• Manage directory share by granting or restricting user access levels

• Linux uses either NFS or Samba to share files; NFS is the native Linux/Unix file sharing service whereas Samba is compatible with Windows systems

Network Applications

• Designed for multiple simultaneous users on numerous computers on network

• Three essential types of network application tools:– E-mail or messaging– Scheduling or calendaring– Groupware

• Easier to administer• Poor network performance or limited

bandwidth degrades application performance

Network Applications (continued)

• If network is down, application is unusable

• Three types of architecture for network applications:– Centralized – applications operate only on

server– File-system sharing – application on client, but

share database or storage directory– True client/server – some resides on server and

some on client; group activities processed on server

E-Mail or Messaging

• Distributes messages across network or Internet– Internet mail standards include SMTP, POP3,

and/or IMAP– See Simulation 8-1 for a visual explanation of

how e-mail operates

• Includes many sophisticated abilities, such as attaching files, filtering, using distribution lists, and address book

E-Mail or Messaging (continued)

• Numerous e-mail protocols, including:– X.400 – hardware- and software-independent

message-handling protocol– Internet Message Access Protocol (IMAP) –

includes advanced message controls and fault tolerance

– Message Handling System (MHS) – Novell standard similar to X.400

E-Mail or Messaging (continued)

• Numerous e-mail protocols, including:– Post Office Protocol, version 3 (POP3) –

used by e-mail clients to download incoming messages

– Simple Mail Transfer Protocol (SMTP) – current standard for Internet e-mail

– X.500 – similar to X.400, but offers improved directory services

Scheduling or Calendaring

• Provides easy coordination of meetings and appointments

• Most offer private and public calendars, appointment books, task lists, and contact address books

• May offer reminders of special events• Often integrated into e-mail programs• May print daily, weekly, monthly, and yearly

schedules

Groupware

• Lets multiple users interact simultaneously with single file, document, or project

• Most popular multiuser multimedia authoring tools include Lotus Notes, Novell’s GroupWise, and DEC’s TeamLinks

• Able to synchronize users and coordinate distributed data and activities

• PDA integration into groupware is exploding so that users can take their calendars and e-mail with them on a handheld