COMPUTER

NETWORKING

By: Dr. Noor Dayana Abd Halim

Defining Computer Network

Computer network is a collection of computers and

other hardware devices so that network users can

share hardware, software, data and they can

communicate with each other electronically.

Defining Computer Network

Computer networking is connecting a computer with

other computers or other devices to enable them to

communicate with each other, between

– computer devices/equipments

– transmission media to send/control data/signals

– communication devices to transmit/send data from

sources to destinations

– softwares

Type of Network

Many types of network depending on the

geographical area.

Type of Network

Type of Network : Local Area Network, LAN

Covers relatively small geographical area. Eg.

Home, schools, office building

Client/ server network is example of LAN

Allows file exchange, emails, printer sharing or

accessing the internet

Type of Network : Metropolitan Area Network, MAN

Network designed to service a metropolitan area, a

city or a county

Owned or provided by a city or network provider

For local people‟s access to internet

Example in Malaysia? 3 network of LAN for Mid

Valley City

Type of Network : Wide Area Network, WAN

network that covers large / broad geographical area

Ex: telecommunications network that links across

metropolitan, regional, or national boundaries) using

private or public network transports.

In essence, this mode of telecommunication allows a

business to effectively carry out its daily function

regardless of location.

Internet: world‟s largest WAN

Type of Network : Wide Area Network, WAN

Network Component

What you need to set up a network?

1. Hots / End Nodes

2. Transmission Media

3. Network Electronics Devices

4. Software / Application

5 Network Architecture Standards & Protocols

Network Component : 1. Hots /End Nodes

Refers to the data source and the data destination.

Examples:

– Personal computers

– Terminals

– Workstations

– Automatic Teller Machine

Network Component : 2. Transmission Media

For transmitting data and control signals

Responsible for sending electric or signal through

spesific media. It can be bounded (wired) or

unbounded (wireless) media

Network Component : 3. Network Electronic Device

Responsible to control data from source to destination

Provide interface between different media transmitter or for different protocol

• To connect multiple network together or to connect computer or network to the internet

•Examples:

– Bridges

– Routers

– Multiplexers

– Switches

– Hubs

– Gateways

– Front End Processors

Network Component : 3. Network Electronic Device

Network Component : 4. Applications/ Software

The applications at the end nodes (what is end

node?) normally involves technique and protocols

The protocol determines the rules and procedure to

send data, terminate data, interpret data, present

data and control mistakes

Software in the network functions to ensure data is

delivered at respective destination

to control data transmission

Network Component : 5. Network Architecture

Standard & Protocol

NAS: The blueprint of standards that define:

– How device in a network typically connect

– How the device can communicate

To ensure interoperability between various devices

and equipment made by different vendors.

To enable devices made by different companies to

work or communicate with each other.

Network Component : 5. Network Architecture

Standard & Protocol

Example : TCP/IP, Ethernet (802.3), Wi-Fi (802.11),

WiMAX etc

Networking Architecture

Network architecture is the way they are design to

communicate

2 types :

1. Client/Server Networks

2. Peer to Peer Networks

Networking Architecture : 1. Client/Server

Networks

1) Client/ server:

Client = computers that request or utilize network

resources

Server = processing the request by client

What is network server? Provide access to software,

files etc being shared in the network

Retrieves file from server: download

Transfer from client to server : upload

Networking Architecture : 2. Peer to Peer

Networks

2) Peer to peer

No central server

Have direct access to other devices attached to the

network

As long as they are declared as „shared devices‟

Internet peer to peer: eg. iTunes, Bluetooth between

handphone

Network Topology

Network topology is the study of the arrangement

or mapping of the elements (links, nodes, etc.) of a

network, especially the physical (real) and logical

(virtual) interconnections between nodes

How the hardware/ devices are placed and

arranged

2 types

1. Physical

2. Logical

Network Topology: 1. Physical

1. Physical topology :

• The physical layout of devices on a network. or the way that the devices on a network are arranged and how they communicate with each other

• The way that the workstations are connected to the network through the actual cables that transmit data

• 5 Types :

1. Linear Bus

2. Ring / Star-wired

3. Star

4. Tree / Hybrid

5. Mesh

Physical Network Topology: 1. Linear Bus

1. Linear Bus

consists of central cable to which all devices are connected with a terminator at each end. ƒ

All nodes (file server, workstations, and peripherals) are connected to the linear cable.

Data transmitted through the bus line from one device to the other.

Network cannot function when the bus line fails.

Ethernet and LocalTalk networks use a linear bus topology.

The message is transmitted along the cable and is visible to all computers connected to that cable.

Physical Network Topology: 1. Linear Bus

Physical Network Topology: 2. Ring

2. Ring

• Each of the systems is connected to its respective neighbor forming a ring.

• Sometimes called “star-wired network”

• The main difference between the bus and ring is that the ring topology does not require termination. Because the systems are connected all together in a loop, there is no beginning and end point as there is with the bus topology.

• No terminator and no bounce back signal.

Physical Network Topology: 2. Ring

Physical Network Topology: 3. Star

3. Star

• All networked devices are connected directly to the central

device (hub) / concentrator

• From central device, all network transmissions are sent

• Data on a star network passes through the hub or concentrator

before continuing to it destination. The hub or concentrator

manages and controls all functions of the network. It also acts

as a repeater for the data flow.

Physical Network Topology: 3. Star

Physical Network Topology: 4. Tree / Hybrid

4. A tree (hybrid)

• Can incorporate structures such as ring, star and bus network in

one large network

• It consists of groups of star-configured workstations connected

to a linear bus backbone cable.

• Allow for the expansion of an existing network, and enable

schools to configure a network to meet their needs.

Physical Network Topology: 4. Tree / Hybrid

Physical Network Topology: 5. Mesh

5. Mesh

• Computers have redundant physical connections to one

another

• When the mesh network is a WAN (such as the

Internet), or a LAN that is divided into multiple

subnets, routers make decisions about which of the

multiple available paths will be taken.

• Decide based on which one is the most „effective‟

Network Topology: 2. Logical

2. Logical topology :

• how the systems communicate across the physical topologies

• the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.

• 2 types:

1. shared media topology

2. token-based topology

Logical Network Topology: 1. Shared Media

1. Shared media

• In a shared media topology, all the systems have the ability to access the physical layout whenever they need it.

• Advantage : the systems have unrestricted access to the physical media.

• Disadvantage : Collisions - If two systems send information out on the wire at the same time, the packets collide and kill both packets. If add more systems to the network, there is a greater opportunity for collisions.

• To help reduce the number of collisions, many networks are broken up into several smaller networks with the use of switches or hubs, and each network is then referred to as its own collision

•Example: Ethernet

Logical Network Topology: 2. Token Based

2. Token-Based

• Have a token that travels around the network.

• When a system needs to send out packets, it grabs the token off of the wire, attaches it to the packets that are sent, and sends it back out on the wire.

• As the token travels around the network, each system examines the token.

• When the packets arrive at the destination systems, those systems copy the information off of the wire and the token continues its journey until it gets back to the sender.

• When the sender receives the token back, it pulls the token off of the wire and sends out a new empty token to be used by the next machine.

Logical Network Topology: 2. Token Based

Advantage : Do not have the same collision problems that Ethernet-based networks do because of the need to have possession of the token to communicate.

• Disadvantage : Latency – Because each machine has to wait until it can use the token, there is often a delay in when communications actually occur.

• Token-based network are typically configured in physical ring topology because the token needs to be delivered back to the originating machine for it to release.

• The ring topology best facilitates this requirement.

Thank You!