Tech Guide B The Details of Networking © John Wiley & Sons Canada, Ltd.B-1

Tech Guide B Tech Guide B The Details of The Details of NetworkingNetworking

© John Wiley & Sons Canada, Ltd. B-1

What We Will Cover

• Network Architecture

• Network Layer Model

• Different Kinds of Networks


NETWORK ARCHITECTURENETWORK ARCHITECTUREA network architecture refers to the design

of a computer system or network. The term usually covers the overall combination of the hardware and software that makes up the network infrastructure. ◦ An open architecture is one where anyone can

know the design, thus allowing anyone to develop software and hardware to work with it.

◦ A closed architecture network has a proprietary design, making it difficult for outsiders to design programs that work with the network.

Most of today’s computer systems are open to allow for easy growth.


CLIENT/SERVER CLIENT/SERVER ARCHITECTUREARCHITECTURE

The most common network architecture is the client/server architecture.


CLIENT/SERVER CLIENT/SERVER ARCHITECTUREARCHITECTURE

• Processing is shared among multiple small computers known as clients that are connected via a network to a host computer known as a server.

• Clients are typically PCs and workstations, a type of high-powered small computer built for specialized applications.

• Servers are computers running server software, with each server typically focusing on a specific task.

• Because both the client and the server are capable of processing, it is shared between the two computers.


THREE-TIERED THREE-TIERED ARCHITECTUREARCHITECTURE

© John Wiley & Sons Canada, Ltd.

Three-tiered client/server architecture uses a client, an application server, and a database server.

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TYPES OF SERVERSTYPES OF SERVERS

Server Type

Purpose

File Provides both software and data files to users

Database Handles queries to a large database and returns matching records

Application

Handles high-speed processing

Web Handles requests for web pages

Mail Sends and receives e-mail for the entire organization

Fax Sends and receives faxes for the entire organization


SERVERS ON A NETWORKSERVERS ON A NETWORK


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CLIENT/SERVER CLIENT/SERVER ADVANTAGES AND ADVANTAGES AND DISADVANTAGESDISADVANTAGESAdvantages Disadvantages

Computing burden can be shared among servers and clients

Programming relationship between clients and servers is more complex

Servers can be specialized to one particular type of task

System upgrades require that all clients and servers be upgraded regardless of location

Upgrading system can be done in small steps

More complex computer and network security issues due to increased numbers of users and client machines with access to networked resources, including data.

Loss of client does not stop other clients from accessing server


PEER-TO-PEER NETWORKSPEER-TO-PEER NETWORKS• It is possible to set up a peer-to-peer

network where each computer in the network is on the same level as other computers, and each computer is equally responsible for overseeing the functions of the network.

• Any two computers in a peer-to-peer network can communicate directly with one another or through intermediate peer computers.

• Peer-to-peer networks may be easier to setup, but are not as efficient as client/server networks.


COMPARING CLIENT/SERVER COMPARING CLIENT/SERVER AND PEER-TO-PEER AND PEER-TO-PEER NETWORKSNETWORKS


NETWORK LAYER MODELNETWORK LAYER MODELA network layer model will

help you understand how the following three elements work together.

The simplified network layer models are:◦application software layer◦network connections layer◦data component layer


NETWORK LAYER MODELNETWORK LAYER MODEL


APPLICATION SOFTWARE APPLICATION SOFTWARE LAYERLAYER

• Application software is the software on each computer on the network that the user sees and uses to send and receive messages and data between computers (Web browsers, e-mail, etc.)

• Application layer protocols: simple mail transfer protocol (SMTP) for e-mail, hypertext transfer protocol (HTTP), electronic data interchange (EDI)

• Message may also be encrypted


NETWORK NETWORK CONNECTION LAYERCONNECTION LAYER

The message from the application software layer is formatted according to whatever protocol will be used to send it over the network.

Transmission control protocol/Internet protocol (TCP/IP) is commonly used.


CONVERTING DATA CONVERTING DATA INTO PACKETSINTO PACKETS• An IP Address is a unique identifier given

to each device directly connected to the network.

• It consists of four groups of numbers in the range 0 to 255 separated by periods.

• The message is divided into smaller digital units called packets, each of which contains a specific number of bytes.


PACKET SWITCHINGPACKET SWITCHING• Packet switching means that individual

packets are routed through the network based on the destination address contained in each packet.

• The same data path can be shared among many computers in the network, and if a computer on the network is inoperable, the packet finds another way to reach its destination.

• A router is a special type of computer that has the sole purpose of accepting packets and determining the best way to send them to the destination computer.

• The sequence order allows the receiving computer to reconstruct the message.


THE FLOW OF PACKETS THE FLOW OF PACKETS THROUGH INTERMEDIATE THROUGH INTERMEDIATE ROUTERSROUTERS


DATA COMPONENT LAYERDATA COMPONENT LAYER• Twisted pair: consists of twisted pairs of

copper wires; similar to that used in telephone systems

• Coaxial cable: used to transmit cable television signals into your home; widely used in networks

• Fibre-optic cable: consists of hundreds of glass fibre strands that can transmit a large number of signals at extremely high rates of speed

• Microwaves: high-frequency radio transmissions that can be sent between two stations

• Wireless: several technologies that allow data to be transmitted without wires


COAXIAL CABLE COAXIAL CABLE COMPARED WITH GLASS COMPARED WITH GLASS FIBRE CABLEFIBRE CABLE


DATA COMPONENT MEDIADATA COMPONENT MEDIA

Media Cost Error Rates Speed

Twisted pair

Low Low Low-high

Coaxial cable

Moderate

Low Low-high

Fibre optics High Very Low High-very high

Radio Low Moderate Low

Infrared Low Moderate Low

Microwave Moderate

Low-moderate

Moderate

Satellite Moderate

Low-moderate

Moderate© John Wiley & Sons Canada, Ltd. B-21

SIGNAL TYPESIGNAL TYPEThe signal type is how data are

sent over the network. A signal can be digital or analog.


ANALOG ANALOG VS.VS. DIGITAL DATA DIGITAL DATA TRANSMISSIONTRANSMISSION

Analog DigitalAdvantages • Reflect natural

phenomena; sound, light, and electricity are all analog

• Low-cost, existing infrastructure for analog transmission

• Less susceptible to noise, resulting in a lower error rate

• Allows transmission of multiple signals over one line at the same time (called multiplexing)

• Faster rate of transmission

• Less-complex and lower-cost circuits

Disadvantages

• More susceptible to noise, distortion, and interference

• Analog phenomena require conversion to digital signals


DATA RATE AND DATA RATE AND BANDWIDTH ISSUESBANDWIDTH ISSUES• The data rate is measured in bits per second (bps).• A digital subscriber line (DSL) transmits computer

data in a digital form along the same telephone line that is used for analog voice communications.

• T-carrier circuits are dedicated digital lines that are leased from a telecommunications company to carry data between specific points.

• The term bandwidth is often used in relationship to data rate and is a measure of how fast data flows on a transmission path.o Baseband: only a single digital signal is carried through

the mediao Broadband: a variety of different analog signals are

being transmitted


MAXIMUM DATA RATESMAXIMUM DATA RATESTransmission Method

Maximum Data Rate

Comments

Standard telephone service

56 Kbps Available everywhere

Digital Subscriber line (DSL)

6 Mbps in; 640 Kbps out

Becoming more available; does not slow down as more people sign up

Cable As high as 55 Mbps, but averages between 200 Kbps and 2 Mbps

Cable must support two-way communication; available in many locations but slows down as more people use it

T-1 to T-4 1.544 Mbps–274 Mbps

Leased lines used for commercial telecommunications


LOCAL AREA NETWORKSLOCAL AREA NETWORKS

• Local area network (LAN): a network connected over a small geographic area

• LANs are popular for o Sharing informationo Sharing resourceso Sharing softwareo Sharing hardware

• Most LANs are client/server networks• LANs can also be implemented

through peer-to-peer networks© John Wiley & Sons Canada, Ltd. B-26

LAN TERMINOLOGYLAN TERMINOLOGY• Ethernet protocol is the

technology standards for connecting computers into a LAN.

• A bus network uses a main cable, called a bus, to connect all clients and servers on the network.

• A gateway is the combination of hardware and software that connects two dissimilar computer networks.

• A bridge connects two similar networks.


WIRELESS LANSWIRELESS LANS Wireless LANs (WLANs) replace cabling

with wireless transmissions that use radio frequencies to transmit information between individual computers.

The individual computers do not communicate directly with each other, but instead through a wireless network hub or router.

Wi-Fi (wireless fidelity), also called IEEE 802.11b standard, the current popular standard for wireless networking, supports data rate of 11 megabits/second, with a typical range through open air of about 200–1000 metres.


LAPTOPS CONNECTED LAPTOPS CONNECTED TO A WIRELESS LANTO A WIRELESS LAN


BLUETOOTH AND PANSBLUETOOTH AND PANS• Personal area network (PAN) is a

technology that enables wireless devices to communicate over a short distance—less than 10 metres.

• Bluetooth embeds a low-cost transceiver chip in each device, making it possible for wireless devices to be totally synchronized without the user having to initiate any operation.

• The overall goal of Bluetooth is to enable pervasive connectivity between personal technology devices without the use of cabling.


THE INTERNET: A THE INTERNET: A NETWORK NETWORK OF NETWORKSOF NETWORKS• Originally developed in the 1960s and 1970s as a

way of sharing information and resources among universities and research institutions, the Internet began its dramatic growth in 1991.

• No one can say exactly how many people are using it, with estimates ranging as high as over 1.10 billion in 2005, and by March 2011, 2.09 billion people were online, representing over 30 percent of the world’s population.*

• A primary reason for the explosive growth of the Internet is the tremendous amount of data, information, and resources that people can access.


*Internet World Stats, “Internet Usage Statistics,” www.internetworldstats.com/stats.htm , retrieved November 15, 2011.

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WHAT IS THE INTERNET?WHAT IS THE INTERNET?• The Internet is a network of networks. • To connect to the Internet, your computer

will usually first connect to a LAN through a network interface card (NIC) or to an ISP through a modem and telephone line.

• The LAN, mainframe, or ISP is connected to a regional network via a high-speed (T-1) telephone line. The regional network links into the backbone of the Internet.


• With each network, there is at least one host computer that is connected to the Internet with full two-way access to other computers on the Internet and with a unique Internet address.

• Each host computer that connects to the Internet uses the TCP/IP protocol for assigning addresses and uses packet switching for exchanging information.


WHAT IS THE INTERNET?WHAT IS THE INTERNET?

CONNECTING TO CONNECTING TO THE INTERNETTHE INTERNET


E-MAIL ADDRESSESE-MAIL ADDRESSES• An e-mail address is composed of two

parts: the user name and the server address.

• The user name is assigned to a person or organization that is connected to a server, and it is separated from the server address by the “at” symbol @.

• The server address (a.k.a. domain name) is the IP address of the e-mail host and serves as an easy-to-remember version of the IP address.


INTERNET OPERATIONSINTERNET OPERATIONSInternet Operations

Purpose

E-mail Asynchronously exchange electronic messages with other Internet users

FTP Download files (software, documents, or data) from or upload files to a server located on the Internet

Newsgroups Participate in a wide variety of online discussion groups

Telnet Work on a computer elsewhere on the Internet

Internet relay chat

Synchronously exchange electronic messages with other Internet users

World Wide Web

Transfer text, images, video, and sound to your computer; search for information on the Internet© John Wiley & Sons Canada, Ltd. B-36

USE OF AN FTP CLIENTUSE OF AN FTP CLIENT


THE WORLD WIDE WEBTHE WORLD WIDE WEB• The Web is a special type of client/server

network.• The Web is a body of software and a set of

protocols and conventions based on hypertext and multimedia that make the Internet easy to use and browse.

• Hypertext is a method of linking related information in which there is no hierarchy or menu system.

• Multimedia is an interactive combination of text, graphics, animation, images, audio, and video displayed by and under the control of a computer.


USING A BROWSERUSING A BROWSER• To access the Web, the client computer uses

software called a browser that initiates activity by sending a request to a Web server for certain information. The Web server responds by retrieving the information from its disk and then transmitting it to the client.

• Browser: application layer software used for sending requests and displaying the results

• Hypertext markup language (HTML): tags in World Wide Web documents that are part of a special publishing language

• Documents on the Web are referred to as web pages, and their location is a website


A WEB PAGE ANDA WEB PAGE ANDSOURCE CODESOURCE CODE


The web page’s appearance…

… is determined by the HTML code

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WEB ADDRESSESWEB ADDRESSES


There are three parts to a URL (uniform resource locator), which is the standard means of consistently locating web pages or other resources on the Internet.

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INTERNET PROTOCOLSINTERNET PROTOCOLS

Protocol Purpose

http Retrieve web pages

File Retrieve files from local hard disk

Telnet Log on to a remote computer connected to the Internet

FTP Download or upload files from an Internet FTP server

mailto Send outgoing e-mail

News Display newsgroup


WIRELESS NETWORKSWIRELESS NETWORKSThe fastest-growing trend in networks is

wireless networks, both WANs and LANs, because it enables devices connected to the network to go virtually anywhere.

In the case of wireless WANs, a mobile telephone client is the most popular method of connecting to the Internet and Web.

A number of mobile telephone companies have collaborated to create a special protocol, called wireless application protocol (WAP), just so their telephones can connect to the Internet.


WIRELESS NETWORKSWIRELESS NETWORKSShort message service (SMS)

is a service for sending text messages up to 160 characters long to mobile telephones

Global system for mobile communication (GSM) protocol is the most widely used standard mobile telephone protocol in the world.


RECAPRECAP

1. What is client/server architecture, and how does it work?

2. How does the network layer model describe a wide area network?

3. How are local area networks configured?

4. How does the Internet work?5. What makes the World Wide Web

valuable to business professionals?
