Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 Networking Basics Topics Covered 1. Computer Networks 2. Local Area Network Advantages Cost Savings Time Savings Centralized Data Security Fault Tolerance Communication 3. Types Of Network Operating Systems Peer-to-Peer Networks LANtastic Windows for Workgroups and Windows 95 Windows NT Workstation Client-Server/ Centrix type NetWare 3.12 NetWare 4.1 Banyan VINES Windows NT Server 4. Network Components Hardware Components The Server The Client Workstation Network Interface Card The Cable System Uninterruptible Power Supply Tape Backup Network Printers Software Components Network Interface Card Drivers Protocol Stacks Network Operating System Client Software The Netware Server Performance Fault Tolerance Security Login Security Trustee assignments Client Support 5. Selecting A Network Defining Network Needs Network Size Client Workstations Network Use Centralized Storage Selecting a Network Operating System 1 Local area network (LAN) Topic 1 – Networking basics 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Revision 1 Jan 2001 The Certified Novell Administrator (CNA) Understanding Netware Components And Commands Supporting Client Workstation Environments Managing Novell Directory Services Managing The Network File System Establishing And Maintaining Network Users And Security Setting Up And Maintaining Network Printing Loading And Updating Application Software Creating An Automated User Environment Developing And Implementing A Backup And Recovery System Managing The Server And Monitoring Network Performance Supporting Network Communications Chapter Summary 2 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 1. COMPUTER NETWORKS When two or more computers are connected so that they can communicate, share the resources with each other, a computer network is created. A computer network that exists in one location is called a local area network (LAN). If two or more LAN in different geographic locations are tied together, a wide are network (WAN) is created. 2. LOCAL AREA NETWORK ADVANTAGES While distributed processing can be performed by stand-alone computers not connected by a network, a LAN offers many advantages by sharing resources and improving communications. These advantages make distributed processing a strong competitor of traditional centralized minicomputer and mainframe computer systems, the traditional means of sharing resources and communicating between users. Fault Tolerance When data is stored on individual workstations there is an increased probability of data loss due to operator error, software bugs, computer viruses, or hardware failure on the workstation. Data stored on the network file servers can be placed on microcomputers that are specially designed and configured to provide protection against loss of data due to software or hardware problems. This is called fault tolerance. Communication The high-speed communication between network computers provided by a LAN creates opportunities for major changes in office management. For example, workgroup-oriented applications such as electronic mail and scheduling are commonly used on LANs. Electronic mail (e-mail) applications enable users to send messages and files directly to other users on the LAN. 3. TYPES OF NETWORK OPERATING SYSTEMS The network operating system (NOS) is the software that controls network services. Depending upon their design, NOSs can be defined as either peer-to-peer or ClientServer/ Centrix type. Peer-to-peer NOSs enable workstations to communicate and share data with each other without the need for a dedicated file server computer. Client-Server/ Centrix type NOSs use one computer as a dedicated file server, which acts as a central storage unit for client workstations. Netware is a Client-Server/ Centrix type operating system because its operation depends upon the existence of a dedicated Netware server. Peer-to-Peer Networks In peer-to-peer networks, each computer can be both a server and a client workstation, allowing any computer to share its files with other users on the network. Each computer can also function as a print server, enabling other users to share its printer. The main advantage of peer-to-peer NOSs is the ability to implement low-cost networks by saving the expense of dedicating a computer as a server. In addition, peer-to-peer systems allow users in workgroups to share data files and to communicate easily with each other. In theory this reduces the burden on the network administrator by placing more responsibility for data sharing in the hands of the users. 3 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 However, large peer-to-peer networks can be very difficult to administer because shared data can exist in several locations, making it more difficult to retrieve, secure, and back up. For example, if workstations containing data needed by other users fails to boot its system or shuts down unexpectedly, other users can lose data or will not be able to access the information they need. In this section you will learn about several peer-topeer NOSs as well as their advantage and disadvantages when compared to Novell Net Ware. Client-Server/ Centrix type Network In a Client-Server/ Centrix type network, file servers running specialized software are used to provide services to client workstation computers instead of having the workstations share data among themselves. As a result, Client-Server/ Centrix type networks, such as those using NetWare, provide the advantages of centralized data storage, reliability, and high performance that are not currently attainable with peer-topeer networks. One reason for the increased performance and reliability of Client-Server/ Centrix type networks such as Netware is that a file server’s hardware can be specialized to perform the function of file sharing by providing multiple high-speed disk channels along with a large memory capacity for file caching. Windows NT Server The Windows NT sever Client-Server/ Centrix type operating system provides client workstations with centralized and highly fault-tolerant high –speed access to data. The advantages of Windows NT are that it provides centralized management of multiple servers through the familiar Windows environment and that it supports access to TCP/IP and Netware servers as well as mainframe computers. A final advantage is its usefulness as an application server, a server that runs the server portion of client/ server applications. Many vendors offer client/server applications designed to run on the Windows NT server. Many network administrators are using Netware as their main network operating system for file and print services while using Windows NT server as application servers. 4. NETWORK COMPONENTS The Client Workstation Generally, each computer that is attached to the network for the purpose of running user applications is referred to as a client workstation. Network Interface Card As defined previously, a LAN is basically a system that enables computers of different types to communicate and share data. A network interface card (NIC) is installed in each computer attached to the network, including the servers. The NIC allows the computer to be attached to the network cable system and is responsible for the transmission and reception of data packets on the network. A packet consists of 500 to 4,200 bytes of formatted data that is framed with control bits identifying the address of the computer it is being sent to and the bits for error checking (data, address, error check). The cable system 4 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 A network’s cable system is the highway through which information travels from one computer to another. A cable system consists of the wiring that connects the computers in the network. 4.1 SOFTWARE COMPONENTS Network Interface Card Drivers Protocol Stacks The protocol stack is the software used to format the requests and information packets that are transmitted on the network. Network Operating System Each server and client workstation must have a network interface card to attach it to the cable system and to communicate on the network. A network interface card driver is software that contains the instructions that allow the processor on the computer to control card functions and interface with the application software. Netware 3.1x is a 32-bit dedicated NOS that introduced the ability to load and unload programs called NetWare loadable Modules (NLMs). This enabled network administrators to add or delete hardware drivers and additional network services without shutting down the server. Netware 4.0x was an earlier version of Netware 4.1x that contained many of the same features, including NDS, but was not widely implemented because of the scope of the changes it introduced combined with some problems that were finally fixed in Netware 4.1. The ability to provide faster support for workstations will become even more important as servers are increasingly used to store large documents, images, and multimedia files. Similarly, the increasing use of application servers to run the server portion of client/server applications is requiring more processing power from the server itself. Client Software Client workstations require the following components: 1. Their own operating systems such as DOS, OS/2, Windows 95/ 98, Windows NT, or Macintosh system 9 to control local devices and run application software. 2. Client workstations driver software to control the network interface card 3. Requester and protocol software programs to format and send requests for network file and print services to the server; the requester program works closely with DOS to provide access to network services. 5.0 THE NETWARE SERVER As explained earlier in this chapter, the main function of a server is to provide file and printer services to client workstations. As a result, the server can be enhanced with specialized hardware and software to improve performance, security, and reliability beyond what can be expected from a peer-to-peer network operating system. Performance The performance of a server is determined by how fast it can respond to requests for data from client workstations. Therefore, the major factors that affect the server’s performance are its ability to keep frequently used information in memory, the speed 5 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 of its disk system, and, if the first two are adequate, the speed of its processor unit. Some of the performance features of Netware are discussed in topic 2. Fault Tolerance Security Login security requires all users of the server to provide a valid user name and optional password before being given access to the network. Trustee assignments Preventing unauthorized access to information on the server is one of the most important responsibilities of a network administrator. Login security Fault Tolerance can be defined as the ability of a system to continue to operate satisfactorily in the event of errors or other problems. Trustee assignments enable you to assign privileges, called trustee rights, to Netware users in order to allow them to perform certain function on the network. Trustee assignments form the basis for Novell Directory Services security, which controls access to Novell Directory Services (NDS). NDS is Novell’s system for managing network resources such as printers and servers. Trustee assignments are also the basis for file system security, which controls access to the network file system (the directory structure of the hard drive and the files in that directory structure). A newly created user has no rights to access any data stored on a Netware server until you provide that user with rights to use certain parts of a file system on a Netware server in your network. Client Support Because a Netware server runs its own network operating system, it is not dependent on a specific type of client environment (unlike peer-to-peer networks) and can support many types of workstations. 6.0 SELECTING A NETWORK Selecting a network system for an organization involves three steps: 1. Deciding on the type of network operating system to use 2. Determining the cable system that will best support the needs of the network 3. Specifying any computer hardware that will be needed to implement servers and attach workstations to the network. In this section you will learn about the criteria you should consider when developing a recommendation for a network operating system. In topics 2 and 3 you will learn about computer hardware options and cable configurations that you will need to know when recommending and implementing a new network or maintaining an existing system. Defining Network Needs Before recommending or justifying a network operating system, you first need to analyze the processing needs of the organization and determine how the network will 6 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 support them. The processing needs of an organization that affect the type of network operating system to be selected include number of users, diversity of workstations, type of applications to be supported, and the need for centralized data. Network Size Client Workstations The types of client workstations that will be attached to the network are another factor to consider in determining the type of network operating system to be selected. Peer-to-peer networks are best used in networks in which all the attached clients are running the same type of operating system. For example, if all workstations will run windows, the Windows 95 system could be an attractive alternative, provided it meets the other processing needs of the network. If the client workstations are running a combination of DOS and windows, the LANtastic or a Client-Server/ Centrix type operating system such as Netware 4.1 might be the best choice, depending upon the organization’s other processing needs. Network Use An important consideration in determining whether to use a peer-to-peer or ClientServer/ Centrix type network operating system is the number of workstations that will be attached to the network. As a general rule, fewer the users, the more likely a peer-to-peer network will meet the needs of the organization. In addition to the size of the current network, you also need to look at the future growth of the organization and how this will affect the network system. If you think that the organization will expand in the next few years to include more users requiring heavy-duty file and printer sharing in order to support such applications as desktop publishing and CAD, you might want to recommend a client–server/ centrix type network operating system. Certain common uses of networks, such as printer sharing and e-mail routing, have small disk storage needs and can run nicely on peer-to-peer networks. For example, if an organization plans to use its network to support workgroup-oriented software such as e-mail and scheduling with some sharing of files and printers within small workgroups, a peer-to-peer operating system that supports its workstation operating systems might be the best choice. If an organization will be running applications that require fast access to large network data files such as desktop publishing, document imaging, and multimedia presentation packages, a Client-Server/ Centrix type network such as Netware should be selected in order to provide reliable, high-speed access to large disk systems consisting of gigabytes of data storage. If the network is using a client/server application, then a Client-Server/ Centrix type network with an application server is necessary. The Windows NT server environment provides a good platform for serving applications because the operating system is designed to support application development. Centralized Storage Another important consideration in selecting a network operating system is the need for the network to contain centralized storage for files and documents. If an organization’s employees use word processors and spreadsheet programs to access common documents and files, a client-sever network system will provide them with consistent and 7 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 reliable shared storage areas that can be routinely backed up in order to provide for disaster recovery. Client-Server/ Centrix type environments are also the best choice when users in an organization need access to large centralized databases containing inventory and customer information. These database files should be placed on a dedicated file server or application server in order to take advantage of the speed associated with file caching and the assurance of high reliability and fault tolerance that can be gained by mirroring or duplexing the disk drives. Selecting a Network Operating System The flowchart shown in Figure illustrates how to analyze the network processing needs of an organization to help select a network operating system. As shown in the flowchart, the number of user workstations to be attached to the network is the first consideration. If there are fewer than 15 workstations, a peer-to-peer system will probably be the best network alternative. However, if several of these workstations will be working with large files that need to be shared on the network, such as those used by departments running computer aided design applications, a Client-Server/ Centrix type network operating system is preferable. The choice of the peer-to-peer network operating system will also depend on the type of operating systems used by client workstations. When the number of users exceeds 15, the need for centralized data typically becomes an important factor in choosing between a Client-Server/ Centrix type and peer-to-peer system. If the network will be used mostly for sharing printer and personal communication, you will need to consider the operating systems that the client workstations will be running. If client workstations will be running different types of operating system, Netware is usually the best operating system choice because it can be configured to support communications and file sharing between different client operating environments. When centralized data storage is a major function of the network, a Client-Server/ Centrix type system such as Netware or Windows NT Server is the best choice because it provides a secure and efficient platform that helps ensure that data will be available at all times. When large database or multimedia files that are critical to an organization’s operation need to be accessed from a centralized server, Netware 4.1x is generally the best choice, depending upon the number of servers. In most situations in which performance, security, and reliability are a must, Netware is probably the best choice because it has been used extensively for many years and its performance and compatibility with many applications are well established. Other Client-Server/ Centrix type environments, such as Windows NT server, are newer to the marketplace and should be considered and researched carefully to determine their performance and compatibility in the proposed network environment. Today many network administrators are gaining the best of both peer-to-peer and ClientServer/ Centrix type networks by implementing networks consisting of combinations of network operating systems. For example, a Netware Client-Server/ Centrix type network can include clients running Windows 95, while Windows NT server is used to provide access to certain Windows NT-based client/server applications. As these operating systems gain popularity, network administrators will be increasingly called upon to implement network systems, using a combination of compatible products in order to provide the services needed by the organization’s LAN users. 7.0 THE CERTIFIED NOVELL ADMINISTRATIOR (CNA) The microcomputer-networking field in an exciting arena with new developments occurring on an almost daily basis. The rapid growth of this field has created the need for 8 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 network professionals, trained individuals who can be trusted with the responsibilities of creating and maintaining LAN and WANs. Although it is not a required prerequisite to take the CNA exam , Novell expects that all CNAs understand DOS and can use DOS commands. This is even true for the Windows 95 environment because the DOS prompt is still available and DOS commands can still be run. 7.1 UNDERSTANDING NETWARE COMPONENTS AND COMMANDS One of the fundamentals a Netware administrator needs is a solid foundation in the components that make up a Netware network and how they interoperate. 7.2 SUPPORTING CLIENT WORKSTATION ENVIRONMENTS The majority of computers attached to Netware networks today run either the DOS or Windows operating system, and therefore, as a CNA, you will need to know how to install and configure the client software used to attach DOS or Windows workstations to the network and establish communications. 7.3 MANAGING NOVELL DIRECTORY SERVICES One of the most important features in NetWare 4.1 is Novell Directory Services (NDS). On a Netware 4.1x network, a user connects to the network itself rather than to a server (or group of servers). This requires a comprehensive, logical network design, as well as tools for administering the resources (such as disk space and printers) for the entire network. Novell Directory Services (NDS) is the tool that you as a CNA will use to create, maintain, and administer the network design and resources. 7.4 MANAGING THE NETWORK FILE SYSTEM A network file system uses a directory structure to define the way in which the data storage of your server(s) is organized. 7.5 ESTABLISHING AND MAINTAINING NETWORK USERS AND SECURITY Netware has a very sophisticated security system that enables the network administrator to provide users with access to information while at the same time protecting special information from unauthorized access. 7.6 SETTING UP AND MAINTAINING NETWORK PRINTING Perhaps one of the most complex and demanding tasks of a network administrator is creating and maintaining the network-printing environment. 7.7 LOADING AND UPDATING APPLICATION SOFTWARE An ongoing and important job of the network administrator is installing and upgrading application software packages that run on the client workstations. Whenever possible you will want to install applications on the server so they can be shared and centrally maintained. 7.8 CREATING AN AUTOMATED USER ENVIRONMENT 9 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 Before the Windows environment became popular, users had to use DOS commands to log into the network or run software programs. 7.9 DEVELOPING AND IMPLEMENTING A BACKUP AND RECOVERY SYSTEM Information is the lifeblood of an organization, and as a CNA you will be the guardian of the information stored on the local area network system. One of the worst nightmares a CNA can have is a server crashing with the loss of all the network information stored on its hard drives. To prevent this catastrophe, you will need to be sure your server environment is as reliable as possible. 7.10 MANAGING THE SERVER AND MONITORING NETWORK PERFORMANCE A Netware server has its own operating system and console commands that enable a network administrator to control the server environment as well as run special software called Netware Loadable Modules (NLMs) in order to perform certain tasks or add new services. 7.11 SUPPORTING NETWORK COMMUNICATIONS In addition to allowing users to share resources on a server, an important use of a LAN is communication among users, as well as access to minicomputer or mainframe computer. 8.0 CHAPTER SUMMARY A computer network is formed when two or more computers are connected so that they can communicate electronically with each other. Local Area Networks (LANs) are located in one location, while Wide Area Networks (WANs) connect two or more LANs. The network administrator is responsible for running the network. Networks use servers, which are specialized computers that provide network services. Examples of servers are file servers, print servers, and application servers. Networks are becoming widespread in many organizations because they provide cost savings by enabling users to share expensive hardware and software, time savings by making it easier for users to work together, shared access to database and document files, a more secure environment to protect sensitive data from unauthorized access, a more reliable storage system to prevent loss of data and time, and a communication system that can be used for electronic mail and scheduling applications, as well as providing access to minicomputer and mainframe computer systems. Network operating systems (NOSs) can be classified into two types: peer-to-peer and Client-Server/ Centrix type. Peer –to-peer operating systems do not require a dedicated server but they are able to share data among the client workstations. Generally, peer-topeer operating systems such as LANtastic, Windows 95, and Windows NT Workstation are best implemented for smaller workgroups that do not require frequent access to centralized data files. Because Client-Server/ Centrix type operating systems such as NetWare and Windows NT Server have dedicated servers, they can be more efficient and reliable platforms for storage of centralized files. When selecting an operating system for your network, you need to consider such factors as the number of users and workstations, the type of operating systems and applications that will be used by the client workstations, and the need for high-speed centralized data storage. In most cases in which a Client-Server/ Centrix type network is needed, NetWare equals or exceeds the capabilities of other system such as Windows NT Server and BanyanVINE. Because each type of operating system has certain strengths, however, many organizations must be able to integrate combinations of network operating systems and workstations in order to meet their network processing needs. Windows NT Server is often chosen as the operating system for an application server. 10 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 In order to succeed as a network administrator, you will need a good understanding of the hardware and software components that make up a network system and how they interoperate. The basic hardware components of a network consist of the server, cable system, network cards, uninterruptible power supply (UPS), client workstations, and shared printers. Printers can be added to the network by attaching them to a local printer port on the server, attaching them remotely to a client workstation, or attaching them directly to the network cable. The software components of a network are: o Driver software for network interface card (NIC); o the protocol stack, which performs the formatting of the data transmitted between computers; o the DOS requester program, which provides as interface between applications and the network; and o the network operating system, which runs on the server computer and provides the shared network services. Network administration is an exciting field with a great future, and a Certified Novell Administrator (CNA) will be in a position to grow with the industry. As a CNA, your responsibilities will include such activities as supporting client workstation applications, creating and maintaining the network directory structures, creating and maintaining the Novell Directory Service (NDS) database and Directory tree, establishing network users and security, setting up and maintaining the network printing environment, managing the server console, maintaining a user-friendly environment, implementing a fail-safe backup and recovery system, and supporting network communications. ____________ 11 Local area network (LAN) Topic 1 – Networking basics Revision 1 Jan 2001 Selecting A Network Operating System Begin <15 Light to Medium Files >15 Heavy, large Files Use Mixed Size No Same Client Type Same Client Type NetWare Central Data Yes Small to Medium Mixed File Size Client type No NetWare Window s No Yes Windows Windows Yes File size NetWare NetWare Yes Windows Large Database Application s On Server No Applications on server LANtastic Windows 95 LANtastic Windows NT Server NetWare Windows NT server No Window s NT Yes Environment Windows 95 OR Windows NT Server Windows NT server Windows NT Workstation 12