3.1 network basic

Chapter Three

3.1 Network Basic

3.1.1 Basic Concept of Network

At the end of this topic, students should be able to:

Explain the concept of network

What to cover?

• Definition of network• Communication device• Transmission media• Advantages and disadvantages of network

What is a network?

A network is a worldwide collection of networks that connects millions of businesses, educational institutions and individuals. (Shelly, 2016)

Pages 470 - 471 Discovering Computers : Chapter 9

What is a network?

A network is basically a wired or wireless network that connects together a group of computing resources such as computers, printers and servers, which are located at different places.(Yew ,Low, 2014)

Pages 470 - 471 Discovering Computers : Chapter 9

Discovering Computers : Chapter 9Pages 460

Communication System

Sending device

Receiving device

Comm. device

Communication channel /

Transmission mediaComm. device

Communications System• A sending device that initiates an instruction to

transmit data, instructions, or information.• A communications device that connects the sending

device to a communications channel.• A communications channel, or transmission media on

which the data, instructions, or information travel.• A communications device that connects the

communications channel to a receiving device.• A receiving device that accepts the transmission of

data, instructions, or information.

Communication DevicesHardware or equipment which are designed to transfer signals or data from a sender to receiver.Example: Hub, switch, modem, router, repeater, access point, network interface card (NIC).

Transmission MediaTransmission media consist of materials or substances capable of carrying one or more signals.(Shelly, 2012)

• A communications channel, or transmission media on which the data, instructions, or information travel.

Types of Transmission Media1. Wired transmission media

The transmission of signals or data by means of wire, cable, or other physical connections (transmitter) between a sender and a receiver.Example: Fiber-optic cable, Cable television(coaxial cable), Internet access(broadband media) and telephone networks(twisted-pair cable)

Types of Transmission Media2. Wireless transmission media

The signals or data are transferred between a sender to a receiver by means of radio (electromagnetic) waves. The sender and receiver are not connected by any electrical or optical wires/cables.Example : cellular radio, satellite, broadcast radio, microwaves, Bluetooth, infrared.

Advantages of Using a Network?

Facilitating communications

Sharing hardware

Sharing data and information

Sharing software

Transferring funds

facilitating communicationsUsing a network, people communicate efficiently and easily via e-mail, instant messaging, chat rooms, blogs, wikis, online social networks, video telephone calls, online meetings, video conferencing, VoIP, wireless messaging services, and groupware.

Sharing hardwareIn a networked environment, each computer on the network can have access to all hardware on the network.

sharing data and informationIn a networked environment, any authorized computer user can access data and information stored on other computers on the network.

sharing softwareUsers connected to a network have access to software on the network.

transferring fundsCalled electronic funds transfer (EFT ), it allows users connected to a network to transfer money from one bank account to another via transmission media.

Discovering Computers : Chapter 9• Page 470 • Figure 9-9

• VirusesWhen computers are connected by a network, the virus can spread itself electronically, at computer speeds.

• Network failureIf the file server fails then no-one on the network can access any files or folders. This means that nobody can do any work. For an organisation, this would be extremely costly and disruptive.

• Slow serviceAs more users log onto the network and request files, send things to be printed and open more software applications, the network can start to slow down.

• CostEvery workstation needs a network interface card to enable it to be connected to the network. Other hardware such as hubs, switches and routers are often needed.

• Expert support requiredNetworks need constant monitoring to ensure that the performance is maintained and that all of the components are working properly. This requires specialist staff such as network managers and technicians who will spend all of their time ensuring that the network works efficiently whenever you need to use it. These staff add a large cost to running a network, but without them, things would start to fail.

Disadvantages of Using a Network?

Chapter Three

3.1 Network Basic

3.1.2 Network Architecture


Explain types of network architecture

What to cover?

Type of network architecture• Peer-to-peer • Client/Server

Differentiate between client/server and peer-to-peer networks, and describe how a peer-to-peer network works

Network Architecture

• The design of computers, devices, and media on a network is sometimes called the network architecture

Discovering Computers : Chapter 9 18Pages 473 – 474Figures 9-13 – 9-14

Client/server network Peer-to-peer network

Peer-to-Peer

• Each computer, called a peer, has equal responsibilities and capabilities , sharing hardware (such as a printer), data and information with other computers.

Discovering Computers : Chapter 9 19Page 475 Figure 9-15

Peer-to-peer network

Client-ServerOne or more computers act as a server, andthe other computers on the network requestservices from the server.

Discovering Computers : Chapter 9 20Page 475 Figure 9-15

Clientclients are other computers and mobile devices on the network that rely on the server for its resources.

Server server, sometimes called a host computer, controls access to the hardware, software, andother resources on the network and providesa centralized storage area for programs, data, and information.

Peer-to-peer versus client-serverNum Peer-to-peer Client-server

1. Every user is taking care of his/her own machine so could be difficult to administer the network

Centralized control by the server can be more efficient at administering the whole network.

2. Easy to install and configure for the computers in the network.

Network professionals are normally needed to manage and maintain the whole network.

3. Cost to install and maintain network is inexpensive.

Cost to install and manage the network can be expensive.

4. Each computer has equal responsibilities and capabilities.

Only servers have high responsibilities and capabilities.

Chapter Three

3.1 Network Basic

3.1.3 Network Topology


Explain types of network topology

Networks

• A network topology refers to the layout of the nodes (computers and devices) in a communications network

Discovering Computers : Chapter 9 24Pages 475 – 477Figures 9-16 – 9-18

Star network Bus network Ring network

A network topology refers to the layout ofthe computers and devices in a communications network.

It refers to both the physical and logical layout of a network.

What Is a Topology?

Physical Topology The arrangement of a cabling is the physical

topology.

Logical Topology The path that data travels between computers

on a network is the logical topology.

Layout of Network

Types of network topology.Three commonly used network topologies are:

Bus network

Star network

Ring network

Diagram of different network topologies.

Ring

Star

Bus

Bus Network Topology A bus network consists of a single central

cable (backbone), to which all computers and other devices connect.

T-Connector

Terminator

BackboneT-Connector

Nodes

Each devices is connected to the single central cable(backbone) through T-Connector.

A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable.

T-Connector

Terminator

Backbone

Bus Network Topology

transmit data, instructions, and information as a series of signal.

Those signals are sent as electrical pulses that travel along the length of the cable in all directions.


When a sending device transmits data, the address of the receiving device is included with the transmission.

If the device address does not match the intended address for the data, the device ignores the data.

If the data does match the device address, the data is accepted.

All devices receive the data but only the receiving device accept them.


Advantages:

1. Bus networks are inexpensive and easy to install. So popular on Local Area Network (LAN).

2. Computers and other devices can be attached and detached at any point on the bus without disturbing the rest of the network.

3. Failure of one device usually does not affect the rest of the bus network.


Disadvantages:

1. There might be disruption when computer or other devices are added or removed.

2. Because all systems on the network connect to a single cable or backbone, a break in the cable will prevent all systems from accessing the network.

3. It is difficult to identify the problem if the entire network shut down.


Star Network Topology All the computers and other devices on the

network connect to a central device, thus forming a star.

Two types of devices that provide a common central connection point to all the other devices on the network are a hub and a switch.

Hub / Switch

Star Network Topology

The device that provides a common central connection point for other devices on a network.

All data that transfers from one device to another passes through the hub or switch.

The hub takes a signal that comes from any device and passes it along to all the other devices in the network.

Hub / Switch

Hub / Switch


Advantages:

1. If one device fails, only that device is affected.

2. Devices can be added to or removed from network with little or no disruption.

3. Easy to troubleshoot and isolate problem.


Disadvantages:

1. If the hub or switch fails, the entire network will be inoperabled.

2. Requires more cable than most of the other topologies.

3. More expensive because of the cost of the hub/switch.


Ring Network Topology On a ring network, a cable forms a closed loop

(ring) with all computers and devices arranged along the ring.

Data transmitted on a ring network travels from device to device around the entire ring, in one direction (clockwise or counterclockwise)

Token passing is one method for sending data around a ring

Each device takes a turn sending and receiving information through the use of a token.

Ring Network Topology

The token along with any data is sent from the first device to the second device which extracts the data addressed to it and adds any data it wishes to send.

Then second device passes the token and data to the third device, etc. until it comes back around to the first device again.

Only the device with the token is allowed to send data . All other devices must wait for the token to come to them.


Advantages:

1. The transmission of data is relatively simple as packets travel in one direction only.

2. Cable faults are easily located, making troubleshooting easier.

3. The uses of token passing enables all devices in a ring topology to share the network resources fairly.


Disadvantages:

1. A failure in any cable or device breaks the loop and can take down the entire network.

2. Data packets must pass through every computer therefore, this makes it slower.

3. A ring network can span a larger distance than a bus network, but it is more difficult to install.


DEFINITION ADVANTAGES DISADVANTAGESA bus network

consists of a single central

cable (backbone), to which all

computers and other devices

connect.

Inexpensive andeasy to install.

There might bedisruption when

computer or otherdevices are added

or removed.

Other devices ca beattached or detached

without disturbingthe network.

Failure of one deviceusually does not

affect the restof the network.

The break in themain cable(backbone)

will prevent all systemsfrom accessing the

network.

It is difficult toidentify the problemif the entire network

Shut down.

Summary:

BUS NETWORK TOPOLOGY

DEFINITION ADVANTAGES DISADVANTAGES

All the computers and other deviceson the network

connect to a central device,thus forming a

star.

If one device fails,only that device

is affected.

If the hub or switchfails, the entirenetwork will be

inoperabled.

Devices can be addedor removed fromnetwork with no

disruption.

Easy totroubleshoot andisolate problem.

Requires more cablesthan most of theother topologies.

More expensive because of the

cost of hub/switch.

Summary:

STAR NETWORK TOPOLOGY

Summary:

DEFINITION ADVANTAGES DISADVANTAGES

On a ring network, a cable forms a

closed loop (ring) with all computers

and devices arranged

along the ring.

Transmission of datais simple as packets

travel in onedirection only.

A failure in any cableor device breaks the

loop and can takedown entire

network.

Cabel faults are easilylocated, makingtroubleshooting

easier.

All devices in ring topolgy share thenetwork resources

fairly.

Data packets mustpass through every

computer, thus makeit slower.

More difficult toinstall than a bus network.

RING NETWORK TOPOLOGY

Chapter Three

3.1 Network Basic

3.1.4 Classification of Network


Differentiate among Local Area Network (LAN), Metropolitan Area Network (MAN) and Wide Area Network (WAN)

Networks typically are classified as:a) LOCAL AREA NETWORK

• Definition• Types of LAN:

– Personal area network (PAN)– Home area network (HAN)

• Advantages and Disadvantages of LAN

b) METROPOLITAN AREA NETWORK • Definition• Type of MAN

– Campus network• Advantages and Disadvantages of MAN

c) WIDE AREA NETWORK • Definition• Types of WAN

– Enterprise private network– Virtual private network

• Advantages and Disadvantages of WAN

MAN

LAN

LAN LAN

MAN

LAN

LAN LAN

MAN

LAN

LAN LAN

WAN

LOCAL AREA NETWORK

LAN

• A local area network (LAN) is a network that connects computers and devices in a limited geographical area

• A wireless LAN (WLAN) is a LAN that uses no physical wires

Discovering Computers : Chapter 9 53• Page 472 • Figures 9-10 – 9-11

LAN (Local Area network)

• Normally used bus network.

Discovering Computers : Chapter 9 54• Page 472 • Figures 9-10 – 9-11

LAN (Local Area network)

Advantages

• Easy to share devices (printers, scanners, external drives)

• Easy to share data (homework, pictures)

• Cost of LAN Setup is low.

LOCAL AREA NETWORK

Disadvantages

• Power - a good LAN is required to be ‘ON’ all the times.

• Security - each computer and device become another point of entry for undesirables.

• if all computers running at once, can reduce speed for each.

• Area covered is limited

LOCAL AREA NETWORK

METROPOLITAN AREA NETWORK

MAN

• A metropolitan area network (MAN) is a high-speed network that connects local area networks in a metropolitan area such as a city or town and handles the bulk of communications activity across that region.

Discovering Computers : Chapter 9 58• Page 473 • Figure 9-12

MAN (METROPOLITAN Area network)

Example of a MAN

Example of a MAN• Surveillance System• Traffic Light Monitoring System• Cable Network TV

Type of MANCampus Area Network (CAN)

• A campus network is a computer network made up of an interconnection of local area networks (LAN's) within a limited geographical area.

• In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.

Type of MANCampus Area Network (CAN)

Example:Campus Area Network (CAN)

Academic Departments

University Library Student

Residence Halls.

Advantages• efficiency and shared access. • All the computer-owning residents of the

area have equal ability to go on line.


Disadvantages• it can be costly

(hardware, software, support, etc.). • security problems • As the network consists of many computers

over the span of a city, the connection can lag or become quite slow.


WIDE AREA NETWORK

WAN

WAN (Wide Area network)

A wide area network (WAN) is a network that covers a large geographic area (such as a city, country, or the world) using a communications channel that combines many types of media such as telephone lines, cables, and radio waves.

The Internet is the world’s largest WAN

Advantages• increased efficiency, ease of

communication, and lowered costs.

WIDE AREA NETWORK

Disadvantages• security problems • training costs• maintenance problems. Large enterprises

will dedicate personnel to maintaining their WAN.

WIDE AREA NETWORK

How Are LAN, MAN, and WAN Different?

How Are LAN, MAN, and WAN Different?

• The main differentiation among these classifications is their area of coverage.

LAN MAN WANLAN, MAN and WAN compared

CRITERIA Geographical Area Provider

LAN Connects computers and devices in a limited geographical area such as computer laboratory.

No provider

MAN Connects computers and devices in a metropolitan area such as town or city.

Single provider

WAN Connects computers and devices in a large geographical area such as country, world.

Multi-provider

Comparison:

CRITERIA Connectivity Technology

LAN Computers are located within the same building, usually connected through wires.

Ethernet, token ring, FDDI, Wifi

MAN Computers connected via telephone lines or modems, fiber optic, cable television.

ATM, SMDS, FDDI

WAN Computers connected via satellite or Internet.

Circuit Switched, Packet Switched

Comparison:

3.1 network basic

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