sc161-lecture4part2

Chapter 4

S C 1 6 1 : P r i n c i p l e s o f I n f o r m a t i o n T e c h n o l o g y

Communication and NetworkPart 2: Computer Network

Thiti Theerathean

Center for Teaching Excellence University of the Thai Chamber of Commerce

E-mail : [email protected]

2

• Introduction to Computer Network.- Types of Computer Network.- The basic Configurations of Computer Network.- The Benefits of Computer Network.

• Network Architecture Model.- OSI Model.- Internet Model.

• Local Area Network.- The Components of LAN.- Topologies of LAN.

• Wide Area Network.- Transmission Facility.- Modulation.- Multiplexing.

SC161: Principles of Information Technology

3SC161: Principles of Information Technology

A Computer network is an interconnection of computers and computing equipment using either wire and wireless over small or large geographic areas.

Twisted pair, Radio wave

Coaxial, Fiber Optic

Fiber Optic, Microwave


Personal Area Network : PAN

A personal area network is a computer network organized around an individual person. PANs typically involve a mobile computer, a cell phone or a handheld computing device such as a PDA.

Bluetooth PANs are also called piconet.


The Big Picture of Computer Network.


The Basic Configurations of Computer Network.

PCs to LAN

LAN to LANs


The Basic Configurations of Computer Network.

PC to WAN

LAN to WAN


The Benefits of Computer NetworkPeople and Organizations use networks for the following reason, the most important of

which is the sharing of resource.

• Resource sharing• Data and information sharing • Better Communications • Reduced Cost• On-line services• Electronic data interchange


How do you sends a message to your friends ?

Message.

Department.

Company.

POST Code.

Country.

Thiti Theerathean.

Faculty of Science.

University of the Thai Chamber of Commerce. Vibhavadee-Rangsit Rd. Dindang

Department of Information & Communication Technology.

Bangkok 10400

Thailand

Application Set

Transport Set


The Open Systems Interconnection Reference Model

The architectural model adopted by the International Standards Organization (OSI) .

Bits

Frame

Packet

Segment

Data

Application Set

Transport Set


The Open Systems Interconnection Reference ModelApplication Interface.

Web browser, File Transfer, e-MailApplication Layer

Presentation Layer Encryption Data.

ASCII, EBCDIC, UNICODE

Session Layer Transmission Control.

Simplex, Half-duplex, Full-duplexApplication Set

Transport Set

Transport Layer Flow Control.

Connection-Oriented, Connectionless

Network Layer Routes data.

IP Address

Data Link Layer Node to Node Transmission.

MAC Address

Physical Layer Send and Receive Bits.

Signal and Media.

https://www.expansys.com/d.aspx?i=112043

https://www.expansys.com/d.aspx?i=112043


The Internet ModelThe Internet model is a most widely used that it is accepted as a network architecture. The

Internet’s Protocol suite is called Transmission Control Protocol/Internet Protocol (TCP/IP).

OSI Model Internet Model Protocols

HTTP FTP POP3 DNS

TCP UDP

IPv4 IPv6 ICMP

Not Specified

User Data

Datagram

Packet

Segment

Encapsulation


The Internet Model in Action.

Router

Router

Link Layer

Internet Layer

Transport Layer

Application Layer

Application Layer

Transport Layer

Internet Layer

Internet Layer

Internet Layer

Link Layer

Link Layer Link Layer

Link Layer

Link Layer


A Local Area Network (LAN) is a communication network that interconnects a variety of data communicating devices within a small geographic area and broadcasts data at high data transfer rates with very low error rates.


Client/ServerMicrocomputer users, or clients, share

services of a centralized computer called aserver.

Peer-to-PeerComputers share equally with one

another without having to rely on a central server.


A Topology is the physical layout of nodes in a network, which often dictates the type of communications protocol used by the network.

Topologies of LANs.

Three Network Topologies.


T-Connector

BUS

Desktop ComputerTerminator

• All nodes are connected to a single wire or cable, called a Backbone.• Node is connected to a backbone with T-connector.• Terminators are required at both ends of the backbone cable.• A message (signal) that is sent by a node travels along the bus through all other nodes.


Server

Desktop Computer

RING

• All the nodes are connected in a closed circle of cable.• Electronic messages are passed around the ring.• The Token determines which user on the network can send information. It is called

“Token passing”


• All devices connected with a central Hub.• The Hub monitors the flow of traffic.• The Hub also acts as a repeater for the data flow and then retransmits the signals to

all other nodes.

Server

HUB

Desktop Computer


A Wide Area Network (WAN) is a data communications network that covers a relatively broad geographic area and that often uses transmission facilities provided by common carriers such as telephone companies.

A WAN is contrasted to smaller Local Area Networks (LANs) and Metropolitan Area Networks (MANs).

Home Network

Company Network

Internet Service Provider(ISP)

InternetSatellite


Transmission Facility.

What is the most efficient way to send message over a WAN network ?



Circuit switching : Best for voice.

Message



Packet switching : Best for data.

1

2

3


Modulation.The telephone system transmit analog signals, the transfer of a computer’s digital data over a

telephone line requires conversion of the data to an analog signal.

• The technique of converting digital data to an analog signal is called “modulation”.• The technique of converting analog signal back to digital data is called “demodulation”

Analog signal

Digital signal

Modem Modulates Signal

Modem Demodulates Signal


Multiplexing.The multiplexing is a technique of transmitting multiple signals over a single medium. It is

performed at the physical layer of the OSI model. For multiple signals to share one medium. The medium must be divided.

Frequency Division Multiplexing Time Division Multiplexing

sc161-lecture4part2

Technology

communication network

network topologies

types of computer network

network architecture

wide area network

local area network lan

mobile computer

centralized computer