Basic Concepts of Computer Networks : Internet, Intranet. Extranet

INTERNET

The Internet, or the Net, is the worldwide, publicly accessible system of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP).

It consists of millions of smaller business, academic, domestic and government networks, which together carry various information and services, such as electronic mail, online chat, and the interlinked Web pages and other documents of the World Wide Web.

Internet is one of the uses of communication. Through the Internet, society has access to global information and instant communication.

INTRANET

An Intranet (intra means within) is an internal network that uses Internet technologies and it is a small version of the Internet that exists within an organisation.

An intranet is a private computer network that uses Internet protocols, network connectivity and possibly the public telecommunication system to securely share part of an organisation’s information or operation with its employees.

Intranet generally makes company information accessible to employees and facilitates working in groups.

Simple intranet applications include electronic publishing of organisational materials such as telephone directories, event calendars and job postings.

EXTRANET

An extranet is a private network that uses Internet protocols, network connectivity, and possibly the public telecommunication system to securely share part of a business’s information or operations with suppliers, vendors, partners, customers or other businesses.

Package shipping companies, for example, allow customers to access their network to print air bills, schedule pickups, and even track shipped packages as the packages travel to their destinations.

COMPARISON BETWEEN INTRANET AND INTERNET

COMPARISON BETWEEN INTERNET AND EXTRANET

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Others Lesson : | click lesson to view |

• Definition
• Types of Networks
• Network Architecture
• Network Topology
• Protocol
• Internet, Intranet, Extranet

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Basic Concepts of Computer Networks : Protocol

Protocols provide the rules on how computers communicate. They define how devices intercommunicate in a network environment.

THE IMPORTANCE OF PROTOCOLS

Before protocols were developed, intercommunication between devices was not possible. Protocols are important as they define how devices, applications or computers communicate in a network.

When two computers on a network perform a single exchange of data or information, they will be busy looking for the best communication process between them.

For example, there will be a protocol to specify the format that the information bits or packets must contain when travelling across this connection.

There are also protocols that are responsible for ensuring that the information bits or data packets are sent or received in a proper sequence.

All these protocols work together as a group to prepare and process data for an exchange of information over a network. We call such a group a protocol stack or a protocol suite.

SOME TYPES OF PROTOCOLS

Hypertext Transfer Protocol (HTTP)

This protocol is used to access, send and receive Hypertext Markup Language files (HTML) files on the Internet.

Simple Mail Transfer Protocol (SMTP)

This protocol is used for transferring e-mail between computers.

File Transfer Protocol (FTP)

FTP is responsible for allowing files to be copied between devices.

Transmission Control Protocol (TCP)

This protocol ensures the delivery of information packets across network.

Internet Protocol (IP) – This important protocol is responsible for providing logical addressing called IP address to route information between networks.

TRANSMISSION CONTROL PROTOCOL / INTERNET PROTOCOL

TCP/IP (Transmission Control Protocol / Internet Protocol) is the internet communication protocol. It is a standard that sets the rules computers must follow in communicating with each other on a network. Some refer TCP/IP as the Internet Protocol Suite.

When you use any applications or programs to access the Internet, these application will use TCP/IP to achieve the task. For example, when you want to surf a network, you will use the internet browser. Your browser then uses TCP/IP to request services from Internet servers. These servers will use TCP/IP

to send the web pages you requested back to your browser.

TRANSMISSION CONTROL PROTOCOL

TCP (Transmission Control Protocol) is the protocol that sets the communication rules between computers. Here, TCP establishes connection between two computers, protects against data loss and data corruption.

TCP is responsible for breaking the data into packets before they are sent. TCP then assembles the packets when they reach a destination.

INTERNET PROTOCOL

IP (Internet Protocol) is the protocol that transfers data from node to node. Here, IP takes care of delivering data packets between two computers. IP is responsible for sending the packets from sender to receiver.

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Others Lesson : | click lesson to view |

• Definition
• Types of Networks
• Network Architecture
• Network Topology
• Protocol
• Internet, Intranet, Extranet

Read More

Basic Concepts of Computer Networks : Network Topology

In networking terms, the structure you are planning to connect the computers to, is called network topology.

Network topology is also referred to as the configuration of a network.

It usually refers to the physical arrangement of the computers and other networking devices that are linked together.

It defines how nodes are connected to one another in a communication network. A network topology must show the nodes and the links between them. The nodes must be an active device connected to the network, such as a computer, printer, hub or a router.

There are three main types of network topology. They are :

1. bus topology,
2. star topology and 
3. ring topology.

BUS TOPOLOGY 

Bus networks are very common in Local Area Networks (LAN). A bus network must have a common backbone (the central cable) to connect all devices.

All nodes share the backbone to communicate with each other on the network. Sometimes, a bus network has more than one server. Sometimes, a server is not needed on the network.

ADVANTAGES OF BUS TOPOLOGY

• Easy implementation. New devices can be added to the backbone or to the existing nodes.
• Failure of a node doesn't affect the entire LAN.
• No disruptions to the network when connecting or removing devices.
• Network can easily be extended, by adding new devices to the backbone or existing nodes.

DISADVANTAGES OF BUS TOPOLOGY

• If the backbone fails, the entire bus network will be affected.
• Network speed decreases when the number of nodes increases.
• Troubleshooting is difficult when one of the nodes fails.

RING TOPOLOGY

 A ring topology consists of all computers and other devices that are connected in a loop. Ring topology is also known as a ring network.

A ring network can be found in Local Area Networks. In a ring network each node 

directly connect to two neighbouring nodes.

A server may exist in a ring network, but it will not connect to all the nodes in the network.

The server, like other nodes, will only communicate to its two neighbouring nodes.

ADVANTAGES OF A RING TOPOLOGY

• Troubleshooting is easy when one of the nodes fails.
• Repair or remove the failing nodes and the network will continue to function.

DISADVANTAGES OF A RING TOPOLOGY

• Implementation is difficult. Network administrator has to terminate the entire network to install a new node between existing nodes.
• A failing node will affect the entire LAN.
• Connecting or removing devices is difficult because network administrator needs to terminate the network in order to do it.
• Network speed decreases when the number of nodes increases.

STAR TOPOLOGY

In the early days of computer networking, all computers were connected to a centralised mainframe computer.

All resources and management of information were centred in this main computer.

The idea of a centralised mainframe computer is where the basic concept of a star topology comes from.

A star topology consists of a central host which acts as the centre, and all nodes connect to the host. A star topology is also known as star network.

• A star network is found in a Local Area Network setting.
• A star network must have a host which acts as the centre.
• The host can be a server, hub or router.
• In a star network, every node will not connect to the neighbouring nodes.
• Every node must connect to the host in order to communicate.
• The host will control the flow of communication in the network.

ADVANTAGES AND DISADVANTAGES OF STAR TOPOLOGY

Advantages

• It is easy to implement. You only add nodes to the host.
• The failure of a node does not affect the entire LAN.
• There are no disruptions to the network when connecting or removing devices.
• The network can be extended by adding new devices to the host or nodes.
• Troubleshooting is easy when the host fails. Simply repair or replace the host and the network will continue to function.

Disadvantages

• If the host fails, the entire LAN will be affected.
• Network speed decreases when the number of nodes increases.
• Troubleshooting is difficult when one of the nodes fails.
• A host must be installed to control the network.

DIFFERENCES OF NETWORK TOPOLOGIES

	Bus Topology	Ring Topology	Star Topology
Structure	there is a single central cable (backbone) and all computers and other devices connect to it	all computers and other devices are connected in a circle	there is a central host and all nodes connect to it
Host existence	depends on network needs	depends on network needs	yes
Connection between nodes	It has no connection between the nodes.	yes	no
Host failure	network can still run	network will fail	network will fail
Node failure	network can still run	network will fail	network can still run
Ease of troubleshooting	Difficult. Need to search for the problematic node one by one	Depends on backbone. If there is a backbone, troubleshooting is difficult. If there is no backbone, the focus is on the two nodes not communicating	Depends on the host. Itis easier to repair the problematic host. However, if the nodes fail, then each node has to be searched
Ease of adding or removing nodes	easy	difficult	average
Number of nodes when extending network	many	limited	limited

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Others Lesson : | click lesson to view |

• Definition
• Types of Networks
• Network Architecture
• Network Topology
• Protocol
• Internet, Intranet, Extranet

Read More

Basic Concepts of Computer Networks : Network Architecture

Network architecture is the overall design of a computer network that describes how a computer network is configured and what strategies are being used.

Network architecture mainly focuses on the functions of the networks. Network architecture is also known as network model or network design.

There are two main network architectures: 

• client/server network
• peer-to-peer network

 

CLIENT/SERVER NETWORK

A client/server network is a network in which the shared files and applications are stored in the server but network users (clients) can still store files on their individual PCs.

A server is a computer that shares information and resources with other computers on a network. A client is a computer which requests services or files from a server computer.

PEER TO PEER NETWORK

Peer-to-peer or P2P network is a network with all the nodes acting as both servers and clients. A PC can access files located on another PC and can also provide files to other PCs.

All computers in the peer-to-peer network have equal responsibilities and capabilities to use the resources available on the network.

With peer-to-peer network, no server is needed; each computer in the network is called a peer.

THE DIFFERENCES BETWEEN CLIENT/SERVER AND PEER-TO-PEER

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Others Lesson : | click lesson to view |

• Definition
• Types of Networks
• Network Architecture
• Network Topology
• Protocol
• Internet, Intranet, Extranet

Read More

Basic Concepts of Computer Networks : Type Of Network

TYPES OF NETWORKS

Three types of networks:

1. Local Area Network or LAN
2. Metropolitan Area Network or MAN 
3. Wide Area Network or WAN

LAN - Local Area Network

Local Area Network (LAN) is the smallest network compared to the other two networks.

The simplest form of LAN is to connect two computers together.

LAN is operated within a limited physical area, such as at home, school, a single building or several buildings.

A network which consists of less than 500 interconnected devices across several buildings, is still recognised as a LAN.

Inexpensive hardware used in LAN previously include twisted pair, coaxial cables and the higher end is fiber optic or wireless. However, coaxial cables are now being replaced by a higher speed cabling system such as CAT5 using RJ45 connectors.

LAN is a very high speed network (from previously 10Mbps) to 100Mbps, which is faster than MAN and WAN.

Local Area Network is a group of computers and network devices connected together, usually within the same building.

MAN - Metropilitan Area Network

First, you have to understand the word metropolitan. Metropolitan describes

important cities such as Kuala Lumpur, Manila, Singapore, Tokyo, London and New York.

MAN is a network of computers located at different sites within a large physical area, such as a city. Companies that have several branches within the Kuala Lumpur city such as banks, might find a MAN useful to them.

In this case, setting up a MAN across long distances can be best connected using fiber optics. Sometimes, a MAN can be a collection of several LANs within the same city.

MAN often acts as a high speed network (although not as fast as a LAN) to allow

sharing of regional resources.

MAN can be defined as a group of computers and network devices connected together within a large physical area.

WAN - Wide Area Network

 

Wide Area Network (WAN) is the largest network of all network types. The Internet is the largest WAN in the world. WAN generally covers large distances such as states, countries or continents.

An example in the society using WAN is the banking organisation. Local banks have always maintained their business online by connecting all computers of their branches in the countries. International banks also use WAN to connect their computers all over the world.

Actually, WAN is a group of MANs or LANs or the mixture of both networks.

A device called a router is needed to connect the MANs and LANs all over a large physical area. A router is a special networking device that connects two or more different networks and keeps data flowing between them.

A router makes all the different networks communicate, such as connecting LAN to LAN, LAN to WAN or WAN to WAN.

The transmission media in WAN uses the fibre optic cable.WAN is still considered a fast network with speeds 20 – 2000 Kbps, but slower than LAN and MAN.

DIFFERENCES BETWEEN TYPES OF NETWORK

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Others Lesson : | click lesson to view |

• Definition
• Types of Networks
• Network Architecture
• Network Topology
• Protocol
• Internet, Intranet, Extranet

Read More