chapter major network functional architectures. chapter objectives discuss the characteristics,...

CHAPTER CHAPTER

Major Network Major Network Functional Functional

ArchitecturesArchitectures

Chapter Objectives• Discuss the characteristics, features etc of

Peer-to-peer and client-server networks• Discuss the emerging concept of thin-

clients• Examine the network operating system in

terms of the client and sever components• Provide an overview of the desirable

characteristics of the server and client hardware

Chapter Modules

• Peer-to-Peer Networks• Client-Server Networks • Server and Client Operating

Systems• An Overview of Client and Server

Hardware

Key Words

• Peer-to-peer, client-server• User level security, resource level

security• hard-resource and soft resource

sharing • scope

– file/folder level access control (client-server)

– folder level access control (peer-to-peer)

MODULE

Peer-to-Peer Network Architecture

Questions

• What are the characterizing features of peer-to-peer architecture?

• Name some application areas of peer-to-peer architecture?

• What are the two different types of access controls that could be imposed on peer-to-peer networks? Focus on the networks that could be set up with Windows 9x and the Windows 2000 or the Windows XP Client operating systems?

Peer-to-Peer Configuration

WorkstationWorkstation Printer

• Share and share alike among peer stations• Absence of a server

Characteristics of a Peer-to-Peer Network

• Simple and inexpensive• Each user

– Manages his or her resources on workstation

– User is also the administrator of his or her resources

• Multi-user applications cannot be implemented

• Limited potential for expansion in terms of applications

Security

• Limited security– If an operating system such as Windows

9x is used for setting the peer-to-peer network

– Uses FAT32• Better Security

– If an operating system such as Windows XP is used for setting the peer-to-peer network

– Uses NTFS

Peer-to-Peer Implementation

• Any number of computers can be connected as long as they are not used for multi-user applications– An example of a multi-user application

is the SQL database application

• Limiting factor – Narrow scope of directory

implementation and peripheral sharing

Peer-to-Peer Sharing

• Simple sharing of resources• Share

– Files– Printers– Sharing an Internet connection– etc.

• Simple messaging • Unsuitable for multi-user business applications• Limited number of connections and limited

sharing

Windows XP Professional

• File and printer sharing• A web server could also be run on

an XP client– However, the connection is limited to

only 10 concurrent users

Limitations in Windows

• Windows XP– 10 concurrent users at any time

• Windows Home Edition– 5 concurrent users at any time

Peer-to-Peer OS

• Windows 7• Windows Vista• Windows XP• Linux

Printer(Password)

Typical Peer-to-Peer Security

Folder(Password)

Network

Workstation (Name)

Peer-to-Peer Security

• No administrator to administer the overall security of the network resources

• Resources are independently administered by the user on each peer computer (client)

• No centralized control on the resources

Operating Systems Supporting Peer-to-Peer

Networking

• Nearly all the client operating systems of today support peer-to-peer networking

Operating Systems Supporting Peer-to-Peer

Networking

• Support for peer-to-peer networking is built into the newer desktop operating systems– Windows 98/95/Me– Windows NT Workstation– Windows 2000 Professional – Windows XP Professional – Windows Vista– Windows 7– Ubuntu Linux (Server and Client OS)– Fedora Linux– Macintosh OS

• A network operating system per se is not required for implementing the peer-to-peer network

Peer-to-Peer Networks

Peer-to-Peer Networks

Windows 9X Windows NT WorkstationWindows 2000 ProfessionalWindows XP Professional

Windows Vista

Share-level accesscontrol

User-level accesscontrol

Peer-to-Peer Networks Based on Windows 9x

• Only share level access control is possible– Access to a resource such as a printer, for

example, can be controlled based on passwords only and not based on user names

• User level access control is not possible where access to the resources could be controlled based on user names– Each user may be given a different type of

access to the resource

A Note on Windows NT, Windows 2000 and

Windows XP

• It is possible to configure peer-to-peer networks with Windows NT Workstation, Windows 2000 Professional, Windows XP Professional, and Windows 7

• Such networks offer better security compared to the same configured with Windows 95/98

• User-level access control is enforced in this case

File Systems

• Windows– FAT32– NTFS 5.0

• Linux– .ext2

• Mac OS– HFS – older version – HFS+ - Later version

Advanced Peer-to-Peer Networks

(Windows 2000/XP Based)

Printer(User)

Folder(User)

Network

Workstation (User)

Peer-to-Peer Sharing of Hard and Soft Resources:

An Example

Folder(Password)

Printer(Password)

Network

Workstation (Name)

Share by attaching as alogical printer to localstation

Shareby accessingat location orcopying to local station

END OF MODULEEND OF MODULE

MODULEMODULE

Client-Server Network Architecture

A Typical Client-Server Physical Architecture

Client Client

ServerPrinter

Note: This is simply a physical client-server architecture.

File ServerApplication ServerThin-client Server

Logical Client-Server Application Architectures

• File server• Application server• Thin-client

Network Servers

• Basic network operating system• DNS server• DHCP server etc.

Client-Server Network Architecture and

Applications• The presence of a client-server physical

network architecture does not necessarily imply that client-server applications are running on the network

• Distinguishing between client-server physical network architecture and client-server applications is important

• A client-server network physical architecture is required to support client-server applications

Client-Server Access Control

• Possible to exercise control at the user level

• Access control can be imposed based on user names

• Different levels of access can be given to different users– Read and Write– Read Only etc.

Client Server Access Control On a Folder

Server

Client Client

TariffUser1 R & WUser2 R

User1 User2 User3

Client-Server Characteristics

• One or more servers are present• Server is the lifeline of the network• The server is optimized for performance• Higher level of security

– User level and share level access control– Login password, station restrictions etc.

• Architecture of choice for most business applications

The Scope

• Networks based on powerful client-server operating systems can support a large number of users and workstations

• Very large networks can be configured by linking smaller client-server network segments together– Active Directory based networks

• Windows 2003 Server

Client-Server Network Application Architecture

• File Server • Application server • Thin-Client

Functional Architectures

Peer-to-Peer Client-Server

File Server

Application Server

Thin-Client

Functional Architectures

Share-Level

Access Control User Level

Access Control

Physical and Application Architectures

Client Client

ServerPrinter File Server

Application ServerThin-client Server

Factors Used in the Comparison of Architectures

• Place of execution for application• Network traffic implications• TCO • Enforcing security• Software requirements

– Server side– Client side

MODULEMODULE

File Server Networks

File Server and Application Servers

• File server is the simplest architecture

• Application server is the more advanced architecture– Forms the core of the implementation

of the client server technology

• Thin-client is also an advanced architecture

Questions to be Asked

• Place of execution for application• Network traffic implications• TCO • Enforcing security• Software requirements

– Server side– Client side

Client

Functional Features of a File Server Running a

DatabaseDepository of shared data, shared applications etc.

Processing of data data takes place at the client

Data files and application files

Database search is performed on the client

Server

Word Execution Alternatives

Client

Server

Microsoft Word stored on local hard disk

(Dedicated application)

Microsoft Word stored on logical hard disk(Shared application)

File Server in a Nut Shell

• The file server basically operates as one large shared storage space for the clients

• Any client with the permission to access the resources on the file server can share folders etc. on the file server

• In effect, the file server functions as a logical disk (network drive) as far as the client is concerned– Compared to a local disk, the difference is that

the logical disk can be shared by other clients as well

The Logical Drive Concept

PhysicalDrive c:

Logical or NetworkDrive f:

Logical drive is physically located at the server.

Client Station

Physically presenton the client

Shared storage from the server

File Server Characteristics

• Shared data is stored on the server and brought to the client for processing

• Shared application software are also stored on the server

• Entire execution takes place at the client• Consequently, considerable network traffic

is generated as the files are ported to the client for processing– Application server networks overcome this

drawback by executing part of the application on the server

Some File Server Concerns

• Powerful clients are necessary as the execution takes place at the client– Total Cost of Ownership (TCO) is high

• More network traffic is generated

File Server Features

• Advantage– Easy to set up

• Disadvantage– Higher network traffic– Higher TCO

MODULEMODULE

Application Servers and the Client-Server Technology

A Note

• Presence of a physical client-server network architecture does not necessarily imply the presence of applications running based on the client-server technology

Client-Server Network and Technology

• Client-Server Network– Physical architecture of a network

• Client-Server Technology– Logical implementation of the

technology for running applications– Presence of an application server is

required to indicate that the client-server technology is in operation

Client

Functional Features of an Application Server

Shared Data and Database Engine

Front-end software

Request for data

Cooperativeand sharedprocessing

ApplicationServer Retrieved

data

Software Examples of the Components of Client-Server

Technology

• Database engine– Microsoft SQL server

• Front-end tool– Microsoft Office suite

Client

Network Traffic in Application Server

Networks

Server

Database data

Retrieved Data

Request for data, not for the entire file

Requested data only

Retrieved data can be processed by anfront end tool such as Excel

Advantages of Client-Server Technology

• Reduction in network traffic– Only the requested data and not the

entire data file is transmitted over the network

• Data can be better administered and controlled– Located on a centralized server and

processed on the server itself

Application Server Characteristics • Server

– Network operating system– Data and database engine– Data search is performed at the server by the

database engine resulting in a reduction in the network traffic

– Better control is exercised on the centralized data

• Client– Front-end software formulates the query– Process and manipulate the data retrieved

Some Application Server Issues

• Because Front-End software is still executed on the client, powerful clients are still required – Total Cost of Operation (TCO) is still

high

MODULEMODULE

Terminal Server and the Thin-Client Concept

A Note

• Terminal server is not synonymous with thin-client– Microsoft’s implementation is terminal

server

• There are other implementations of the thin-client concept as well– Sun Microsystems implementation

(Network Computer ??? Java Machine ??)

General Implementation Architectures

• Network PC (NetPC)• Network Computer• Task:

– Perform an Internet search to study the difference between the two types of implementations

NetPC

• Industry specification for thin-client computing

• Typical use is for OLTP• Basic bare minimum terminal that

would access a powerful thin-client server– It is also known as server based computing

• Access Dell and find the properties of a thin-client

Network Computer

• Proposed by Oracle and Sun• No CD-ROM players, diskette

drives, and expansion slots,• Managed centrally• Likely to be based on a non-Intel

microprocessor• Unlike Windows, this may be based

on a Java based operating system

Terminal Server and Remote Execution Software

• PCAnywhere– This is not a terminal server

application– It is a remote execution software

Thin-Client Architecture

• Presence of a thin-client server is often required

• A server that supports the thin-client architecture

Client

Operation of an Thin-Client Server

Shared Data and Database Engine

MinimalSoftware

Keystrokes and mouse clicks

Screen images

Thin-ClientServer

Commercial Examples

• Microsoft Terminal Server• Citrix MetaFrame• www.sun.com

– Explore Sun’s thin-client solution

Web Research

• Explain the features of the following two thin client implementations– Network Computer– NetPC

• Visit www.compaq.com and obtain information about Compaq’s thin client offerings

• Visit www.citrix.com and obtain an exploratory information on Citrix’s implementation of thin-clients also know as Metaframe

Key Words

• Embedded OS• Application Service Providers• Virtual Private Network

Multiple Architectural Configurations

NFS File Server

SQL Database Engine

Unix Machine

File Server

Application Server

Terminal Server

Module

Client Server Technology

Basis for Client-Server Technology

– Client-server networks– Application servers– Information storage and retrieval is at

the server– Manipulation of the retrieved

information is at the client

Client-Server Advantages

• Centralized administration and control

• Better security• Powerful network operating system• Support for Internet and Intranet

Client-Server Scope

• Large number of users– As per network OS License

• Large number of servers and clients

• Larger networks can be supported– Clustering and linking or workstations

Security

• Centralized and powerful• User and share level access control• Login password• Station and time restrictions• etc.

Client-Server Reliability

TapeDisk DiskMirror

Redundancy Backup

Different levels of RAID implementation are available to ensure reliability.

MODULEMODULE

Server and Client Hardware

Server Hardware

• Powerful hardware should be used – Because it is engaged in multitasking– Largely limited by the scale of

economy

• Hardware changes rapidly• It is not possible to give specific

examples as to the exact type hardware that should be used

Guideline for Server: CPU

• Highest speed at the time of implementation

• Consider using a server with multiple processors

Guide for Server: Memory

• 1G Bytes –16G Bytes is not unusual • Higher memory is recommend• Better memory technology

– SDRAM, RDRAM, DDR, DDR2 RAM etc.

• Higher front-side bus speed– newer computers operate at a speed of 800

M HZ– There are newer memory chips that support

this bus speed as well

Guideline for Server: Storage

• Require storage in Gigabytes• Use a faster and better storage

technology– ATA/66,100,133– Serial ATA– SCSI 1, 2 and 3– SCSI 3 operates at 160M Bytes per second

• Cutting edge of storage technology– Fiber channel storage

RAID Storage

• Multiple disk arrays for fault tolerance

Storage Area Network (SAN)

• Storage Area Network– Built on fiber channel

Advantage of Fiber Channel Technology

• Operates at a speed of 200M Bps• Storage bus can span several miles• A large number of storage devices

can be clustered together– Possible to support terabytes of

storage

Client Hardware• Rule of thumb

– As powerful as a single user microcomputer required to run the applications

• Reason– A number of applications are still

executed at the workstation• Exception

– Thin clients• Terminals supported by the Windows

Terminal Server

A Guideline for Choosing Client Hardware

• Largely determined by the client operating system and the network applications

• Example: Windows XP, Windows Vista– Choose the hardware to satisfy Windows XP

requirements on a single desktop

• Exception is a thin client– Network PC– Network Computer based on a Java oriented

network architecture

Microsoft-Intel Hardware Specifications

• Released on a yearly basis• Combined effort between Microsoft

and Intel• Sample specifications for a

particular year– Access Microsoft’s website

Web Research

• Visit a server vendor such as www.compaq.com and obtain the special features of a server– RAID storage– Hot-swappable components– I/O technology– UPS

In Summary

• In a file server or client-server environment:– the client must be powerful to run the

client OS and the associated applications

• In a thin client environment: – CPU, memory and the hard disk

storage space could be kept to a minimum

MODULEMODULE

Practical Network Operating Systems

Overview of Operating Systems in a Network

• Basic network operating system– Windows 2008 – Windows 2003 Server R2– Windows 2003 Server– Windows 2000 Server– Windows NT Server– Mac OS – Linux

• Client operating system– Windows Vista, Windows XP, Windows 2000

Professional, Windows ME, Windows 95/98, Windows NT Workstation, Linux etc.

Examples of Basic Network Operating System• Windows 2008

– Replacement for Windows 2003 Server

• Windows 2003 Server– Replacement for Windows 2000 Server

• Windows 2000 Server– Successor to Windows NT

Network Operating Systems (Continued)

• Novell NetWare– Still a popular OS– Market share is being eroded by the

Windows NT Server operating system• OS/2

– Released by IBM• Unix/ Linux

– A true multi-user operating system

Observations on Practical Operating Systems

• Most popular current NOS is Windows 2003/2000– Outsells both Unix and Novell

• Supports the hosting of specialized server operating systems

• Unix, however, has been popular for a considerable period of time mainly on mini and mainframe computers– By way of Linux, it is now emerging as a

viable networking operating system for the microcomputer as well

MODULEMODULE

Unix

UNIX the Multi-user Operating System

• A popular operating system• Not considered as a classical

network operating system• Difference is in the method of

execution of the applications

Client(Terminal)

Execution Process in a True Unix Environment

TCP/IP

Central UNIX Unit

Shared spreadsheet data

Spreadsheet software (Excel)

Input (information) from the terminal

Output (results) to the terminal

Shared data and execution

Display and input of data

Comparison with File Server and Execution

Server Environment

• File server– Entire execution takes place at the

client• Application server

– Execution is shared between the server and the client

• True Unix operating environment– Entire execution takes place at the

central unit

Advantages

• Clients need not be powerful– They operate only as a terminal

• Operation and data are confined to a central unit– Entire computer system can be managed at

a lower cost

• Central storage and execution is gaining popularity– Microsoft Terminal Server

Unix as a File Server

Unix FileServer

Windows95/98

Windows NTWorkstation

UnixClient

Storage device

NFS

Linux as a File Server

Linux withSAMBAServer

Windows95/98

Windows NTWorkstation

UnixClient

Storage device

Difference Between the Two Implementations of

Unix

• True Unix implementation– Execution of the application takes place

on the (Unix) server– Shared data is also stored on the server

• Unix as a file server– Only the shared data is stored on the

Unix server– Execution of the application is

performed on the workstations (Clients)

Popular Unix Implementations

• SCO Unix• Red Hat Linux• AIX• Mac OS 10

SCO Unix

• Popular implementation of Unix on LANs– Especially on the Ethernet network

• Supports the implementation of a true multi-user Unix environment

• Could also be used to configure a Unix file server

Linux

• Released as a shareware• Refined by many commercial

companies– Linux is available as a professional

network operating system

• Available at a very low price• For example: Apache web server is

often hosted on Linux• Apache is also a shareware

Popular Linux Implementations

• Ubuntu Linux• Red Hat• Mandrake• Corel• Open Systems (Caldera)• SuSe

AIX

• IBM’s version of Unix• Often implemented on IBM’s RS

6000 series of computers• RS 6000

– Designed for Unix– In power, on par with mini computers

Processor Types and UNIX

• Processor type– Reduced Instruction Set Computers (RISC)– Complex Instruction Set Computers (CISC)

• UNIX – Usually implemented on RISC processor

• Linux– If not the only UNIX version optimized for

non-RISC processors – An example in this case is Intel based

machine where Intel cannot be classified as a RISC processor

UNIX Implementations

• Sun – Sun Solaris• IBM RS 6000 – AIX• Intel PCs - Linux• Mac - Mac OS 10

– A version of Unix based on the BSD version?

Finally

• Unix is also implemented on mini and mainframe computers as well

MODULEMODULE

Practical Server Types

Functional Servers

• Example:– Web server

• Purpose of a a web server– Host a web site

Some Server Types

Server

ClientClient

Database

Server

File

Server

Communication

Server

Messaging

Server

Web www.serverwatch.com

Implementation of File Server

• Basic network operating system • This could well be the Windows NT

Server operating system

Implementation of Specialized Servers

• Requires additional server software• Application server

– SQL server– Basic network operating system

• Web server– Internet Information server– Basic network operating system

• Messaging server– Exchange server– Basic network operating system software

Implementation of Two Different Specialized Servers

ClientClient

Basic Operating System

Client

SQL Server

Messaging Server


Basic Network Operating System

Specialized Server Implementation on a Single

Physical Server

SQL Server

Client

Speci

aliz

ed

Serv

ers

Basic NetworkOperating System

Messaging Server

Basic Network Operating System

Hosting of Two Servers Example

Web Server

Client

Speci

aliz

ed

Serv

ers

Basic NetworkOperating System

SQL Server

Factors Deciding the Hosting of Servers

• Load on the server• Types of applications hosted on

the server

Web Research

• Visit www.serverwatch.com to obtain more information on the different types of servers and their functions

• Storage Area Network– www.unisoninfo.com

MODULEMODULE

Practical Specialized Server Operating Systems

Specialized Server Types• Web server

– Microsoft Internet Information Server– Lotus Domino Server– Apache Server

• Messaging server– Microsoft Exchange Server– Lotus Notes Server

• Database server– Microsoft SQL Server– Oracle SQL Server

Other Specialized Server Operating Systems

• Mainframe Gateway Server– Microsoft SNA server

• Network Management Server– Microsoft System Management Server– Client management is an important aspect

• Firewall Servers– Microsoft Proxy Server– Prevent unauthorized access from either

direction

Internet e-commerce Related Server Operating

Systems

• Internet Commerce Server– Microsoft Merchant Server

• Transaction and Load Balancing Server– Microsoft Transaction Server

• Suite of Servers– Microsoft Site Server

Example of an Actual Implementation of the

Different Servers

ClientClient


Client

Application Server

Messaging Server


File and Printer Servers

ClientClient

Server

File

Server

Other

Printer

In most cases, File Servers also act as Print Servers.

Servers and Services within Windows 2000

• File Server• Print Server• Application Server• WWW Server• Media Server etc.

END OF MODULE END OF MODULE

END OF CHAPTEREND OF CHAPTER

chapter major network functional architectures. chapter objectives discuss the characteristics,...

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