Guide to Networking Essentials

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Nov 7, 2013 (3 years and 9 months ago)

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Guide to Networking Essentials

Fifth Edition

Chapter 9

Understanding Complex Networks

Guide to Networking Essentials, Fifth Edition

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


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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: CIFS, SMB, NFS, AFP, NCP


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

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Client
-
Based Solutions

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Client
-
Based Solutions (continued)

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Client
-
Based Solutions (continued)

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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

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Vendor Options


Many NOSs are available from vendors such as
Sun, SCO, and IBM


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

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Microsoft Redirector


All Windows OSs, starting with Windows for
Workgroups, include the Microsoft redirector, Client
for Microsoft Networks


Designed to access CIFS or SMB
-
based file systems
across a network


Installing the OS installs the redirector automatically


The server component (File and Printer Sharing for
Microsoft Networks), 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

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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


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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

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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, 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
resources through a Web browser

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Novell Networks (continued)

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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

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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

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Mac OS X


Mac OS X differs from previous versions


Includes network client software to run in a
Macintosh, Windows, or UNIX environment


Negates 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

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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

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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


For more robust security, use WPA or 802.11i

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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

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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


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Understanding Terminal Services
(continued)


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



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Understanding Terminal Services
(continued)

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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

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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)


Mainframes continue to be important computing
resources today and for the foreseeable future

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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

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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


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Client/Server Model in a Database
Environment (continued)


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

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Advantages of Working in 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

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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

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

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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

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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