Chapter 9
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
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
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
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
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
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
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
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 platform-independent access to a NetWare network’s
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
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
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
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
Integrating PDAs into a Corporate Network
• PDAs can run Web browsers, e-mail 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
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
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
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
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
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)
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
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
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
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
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
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
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
