Chapter 9 Understanding Complex Networks

Transcription

1 Chapter 9 Understanding Complex Networks

2 Objectives Explain how to implement a multivendor network environment Discuss the differences between centralized and client/server computing Define the client/server networking environment Discuss the basics of Web-based computing environments Guide to Networking Essentials, Fifth Edition 2

3 Implementing Multivendor Solutions For a multivendor environment to work effectively, server s OS, clients OSs, and redirectors must be compatible Different OSs use different methods to access files across a network Two basic ways to get the file systems from different OSs to communicate: from the client end and from the server end Depends on which vendors products to interconnect Guide to Networking Essentials, Fifth Edition 3

4 Client-Based Solutions Guide to Networking Essentials, Fifth Edition 4

5 Client-Based Solutions (continued) Guide to Networking Essentials, Fifth Edition 5

6 Client-Based Solutions (continued) Guide to Networking Essentials, Fifth Edition 6

7 Server-Based Solutions To implement a server-based multivendor solution, software must be loaded on the server to provide services for a particular client If a Windows Server 2003 network includes Macintosh hosts, the administrator can add Services for Macintosh to any of the Windows server OSs Windows Server 2003 NOSs include this service Then, Macintosh clients can connect to resources on the Windows server Similarly, Windows servers can be outfitted with Windows Services for Unix Guide to Networking Essentials, Fifth Edition 7

8 Vendor Options This chapter focuses on the four most popular PC operating system product vendors: Microsoft, Linux, Novell, and Apple In an effort to ease connectivity between different NOSs, these companies include utilities in their OSs to allow simple connectivity between clients and servers from different vendors Guide to Networking Essentials, Fifth Edition 8

9 Microsoft Redirector All Windows OSs, starting with Windows for Workgroups, include the Microsoft redirector, Client for Microsoft Networks Designed to access CIFS (Common Internet File System) or SMB (Server Message Block)-based file systems across a network Installing the OS installs the redirector automatically The server component used for sharing files and printers via CIFS or SMB, is installed automatically Allows users of Windows PCs to easily share their own files and printers with other network users Guide to Networking Essentials, Fifth Edition 9

10 Microsoft in a Novell Network To connect a Windows client to a Novell NetWare network running IPX/SPX: NWLink and Client Service for NetWare (CSNW) must be loaded on that Windows machine To connect a Windows Server 2003 system to a NetWare network: NWLink and Gateway Service for NetWare (GSNW) must be loaded on server GSNW allows Windows clients running Client for Microsoft Networks to access NetWare resources by using the Windows server as an intermediary Guide to Networking Essentials, Fifth Edition 10

11 MS-DOS Clients MS-DOS has no built-in network capabilities Each NOS vendor offers utilities to allow MS-DOS clients to connect to servers of all four types Microsoft, Novell, Linux, and Apple Each utility can coexist with other utilities to provide MS- DOS client connections to all servers In an Apple Macintosh network: AppleShare PC software, LocalTalk card In Linux-based network: Sun Microsystem s PC-NFS, or Linux can run Samba Guide to Networking Essentials, Fifth Edition 11

12 Novell Networks NetWare provides file/print services for other OSs Windows clients: Microsoft Client for NetWare or Novell Client Macintosh clients: Novell Client for Mac OS; if necessary, NetWare servers can support AppleTalk With Novell NFAP (Native File Access Pack): Windows CIFS/SMB clients, UNIX/Linux NFS clients, and Macintosh clients (AFP) can have network file access to NetWare resources Novell NetStorage (NetWare 6.5) provides platformindependent access to a NetWare network s resources through a Web browser Guide to Networking Essentials, Fifth Edition 12

13 Linux/UNIX Networks Network File System (NFS) permits networked machines to export portions of their file systems After a NFS volume is published on the network, authorized users can mount it in the local file systems Mount point Also supports printer sharing To access NFS, PC clients need additional SW Administrators prefer to add Samba to their Linux servers instead Is open source and allows Linux/UNIX machines to masquerade as a native Microsoft network server Guide to Networking Essentials, Fifth Edition 13

14 Apple Macintosh Included in every Macintosh are the OS files and the hardware required to communicate in an AppleTalk network The AppleShare networking software automatically provides file sharing and includes a print server that allows computers to share printers Guide to Networking Essentials, Fifth Edition 14

15 Mac OS X Mac OS X differs from previous versions Includes network client software to run in a Macintosh, Windows, or UNIX environment Removes the need for Windows servers to install special services for Macintosh computers or AppleTalk (provides SMB services) Built on a UNIX core Backward-compatible support for traditional Macintosh file sharing through other Macs, Windows, or NetWare servers providing Macintosh services Guide to Networking Essentials, Fifth Edition 15

16 Handheld Computing Environment There s no clear HW/SW standard on which to rely Lack of compatibility between manufacturers Handheld computers rarely connect to the LAN Options for connecting include Ethernet, but also USB, Wi-FI, Bluetooth, and serial links Handhelds connect directly to PCs to synchronize Maintaining a working and secure environment for handhelds is a latest challenge for administrators Server-based SW can handle synchronization, backup, and application loading for handheld computers in a company Guide to Networking Essentials, Fifth Edition 16

17 Integrating PDAs into a Corporate Network PDAs can run Web browsers, clients, etc. The majority come equipped with a Wi-Fi connection, allowing them to synchronize data with the user s PC and access corporate data and the Internet directly through a Wi-Fi access point Administrators are being asked to set up wireless access points and special Web content, and even write new applications to accommodate PDAs Security is also a concern Wired Equivalent Privacy (WEP) may not be enough For more robust security, use WPA or i Guide to Networking Essentials, Fifth Edition 17

18 Centralized Versus Client/Server Computing In centralized computing, mainframes perform all processing Dumb terminals connect directly to the mainframe PCs and thin clients can also access a mainframe Generally character-based, these applications require little input from the PC, thin client, or terminal Traffic increases greatly because for every keystroke, a packet is sent across the network to the mainframe Then, mainframe sends a (maybe large) response Client/server computing is used instead of centralized computing applications Guide to Networking Essentials, Fifth Edition 18

19 Understanding Terminal Services Halfway through the Windows NT Server product cycle and with the release of Windows 2000 Server, Microsoft included Terminal Services Makes it possible for older, less capable PCs, thin clients, or narrow-bandwidth remote users to run large or complex Windows applications For each user, the server running Terminal Services runs a software-based virtual PC The only processing that the local client handles is user input and displaying program output Guide to Networking Essentials, Fifth Edition 19

20 Understanding Terminal Services Well suited for: Providing access to modern Windows applications on older PCs or thin clients Providing access to centralized applications or services (instead of installing them on client PCs) Allowing remote clients using narrow bandwidth connections to access powerful Windows applications Remotely administering computers Guide to Networking Essentials, Fifth Edition 20

21 Thin-Client Computing Some OSs include capabilities for thin clients to connect to the server, access resources, and run applications, all with considerably fewer resources than a typical desktop computer Thin clients add the following benefits to the computing environment: No removable storage No hard drive Lower total cost of ownership Guide to Networking Essentials, Fifth Edition 21

22 Back to the Future: The Mainframe Environment The mainframe computers introduced to users in the late 1950s and early 1960s also introduced the centralized computing model, which is the basis of terminal services Today, certain transaction-intensive applications such as large-scale airline, hotel, and rental car applications work well with mainframes and terminals (or terminal emulation) Guide to Networking Essentials, Fifth Edition 22

23 Client/Server Environment Client/server model is currently the most popular Easy to implement and scalable Client/server computing generally refers to a network structure in which the client computer and server computer share processing requirements Some services provided by file servers are often not considered client/server e.g., shared-file storage Doesn t make full use of a server s potential Does not solve the problem of network traffic A prominent use of client/server model is the WWW Guide to Networking Essentials, Fifth Edition 23

24 Client/Server Model in a Database Environment Database management systems (DBMSs) are an example of efficient use of the client/server model The client uses Structured Query Language (SQL) to create requests that the database can understand Major components Front end or client Back end or server Guide to Networking Essentials, Fifth Edition 24

25 Client/Server Model in a Database Environment Requesting data from a server in SQL: 1. The user requests the data 2. The client software translates that request into SQL 3. The SQL request is sent across the network to the server 4. The server processes the request 5. The results are sent back across the network to the client software 6. The results are presented to the user Guide to Networking Essentials, Fifth Edition 25

26 Advantages of a Client/Server Environment Uses client and server computers more efficiently Makes better utilization of network bandwidth Client PC s configuration can be less complex Smaller processor and less RAM than server Drive space can be reserved for local applications Network bandwidth is conserved (in contrast to a shared-file database application) Centralized location Better for security and backup process Guide to Networking Essentials, Fifth Edition 26

27 Web-Based Computing Environments Many traditional OSs make file and print services available over a standard Web browser NetWare s NetStorage WebDAV allows a Web browser to carry out traditional file system tasks ASPs (Application Service Providers) offer businesses access to their tools and applications through a Web browser Customers pay as they go for using the application Developed using standards as Java and XML Reduces reliance on in-house IT staff Guide to Networking Essentials, Fifth Edition 27

28 Summary Interconnectivity between multiple-vendor operating systems is often necessary in networking A client-based multivendor network environment relies on the client computer s redirectors to decide which server should be sent the request In a server-based solution, the server supports multiple client types Using the processing power of a mainframe computer creates a centralized computer environment Guide to Networking Essentials, Fifth Edition 28

29 Summary (continued) Server-based terminal services can provide useful access to networks and centralized server-based resources for remote users or single-use workstations Handheld computing environment is growing rapidly In a client/server computing environment, the PC and server share processing and use the resources of both machines more efficiently Most DB management systems use SQL for queries The trend in today s networking environment is to remove the obstacles and incompatibilities of working in a multivendor environment Guide to Networking Essentials, Fifth Edition 29