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 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: – 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

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

or Messaging (continued) Numerous 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

or Messaging (continued) Numerous protocols, including: –Post Office Protocol, version 3 (POP3) – used by clients to download incoming messages –Simple Mail Transfer Protocol (SMTP) – current standard for Internet –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 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 with them on a handheld