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CHAPTER 3 : INTERNET TECHNOLOGY (3.1 Network Basics) (NETWORK (advantages,…
CHAPTER 3 : INTERNET TECHNOLOGY (3.1 Network Basics)
NETWORK
definition
A collection of computers and devices connected together via communication devices and transmission media
Communication devices
refers to any hardware that transmits data, instructions, and information between a sending device and a receiving device
examples
Network Cards, Modems, Wireless Access Points, Routers, Hubs and Switches
Transmission media
refers to the materials or substances capable of carrying one or more signals
types
–Physical transmission media (wired)
use wire, cable, and other tangible materials to send communications signals
examples
–Twisted-pair cable
–Coaxial cable
–Fiber-optic cable
–Wireless transmission media
send communications signals through the air or space using radio, micro wave, and infrared signals
examples
–radio waves
–microwaves
–infrared
examples
cable, radio signal, satellite signal
advantages
•Share data and information
•Share hardware and software
•Facilitates communications
•Transfer fund
disadvantages
•Theft of personal information
•Virus threat
•Pornography
•Social disconnect
NETWORK ARCHITECTURE
definition
refers to the design of computers, devices, and media on the network
types
•Peer-to-Peer (P2P
)
•A network in which each computer (called peer) have equal capabilities and responsibilities to share hardware, data or information with other computers on the network.
•Each computer stores files on its own storage devices.
•Suitable for small network where high level security is not necessary.
advantages
•Easy and inexpensive to set up the network.
•More reliable because failure of one peer will not affect other peers.
•All the peers can share their resources to others.
disadvantages
•Lack of security control or other management functions.
•Data recovery or backup is very difficult. Each computer have to maintain its own backup system.
•Client/Server
definition
•A network in which one or more computers act as a server, and the other computers, called client, request services from the server.
–A server, or host, is a computer that controls access to hardware, software and other resources on the network and provides a centralized storage for programs, data and information.
•Efficient for large network which handle sensitive and confidential data.
–Clients are other computers or devices on the network that rely on the server for its resources.
advantages
•Centralized control by the server promotes better security and management of the network.
•Data backup and recovery is easier since all data is stored in the server.
disadvantages
•Less reliable because too dependent on the server; failure of server will affect the network.
•Network congestion may occur if too many clients request services from server at the same time.
•High cost to set up and maintain the network.
NETWORK TOPOLOGY
definition
refers to the layout of the computers and devices in a communications network
types
•Ring Topology
Data Transfer:
•Data transmitted on a ring network travels from one device to another around the entire ring in one direction.
•When a device sends data, the data travels to each computer on the ring until it reaches its destination.
Advantages:
•Can span a larger network than a bus network.
•Cable faults are easily located, making troubleshooting easier.
•The transmission of data is relatively simple as data travels in one direction only.
Layout:
•All computers and devices are arranged along a cable that forms a closed loop.
Disadvantages:
•More difficult to install compared to bus network.
•Failure of any cable or node will affect the operation of the entire network.
•Slower data transmission as the data sent will go through all the nodes.
•Star Topology
Data Transfer:
•All data that transfers from one node to another passes through the hub or switch.
•The hub takes a signal that comes from any device and passes it to other devices in the network.
Advantages:
•Failure of one node will not affect the entire network.
•Devices can be added to or removed from the network with little or no disruption to the network.
•Easy to identify problems, making troubleshooting easier.
Layout:
•All computers and devices are connected to a central device (hub or switch).
•Hub or switch are devices that provide a common central connection point for nodes on the network.
Disadvantages:
•Failure of hub or switch will shut down the entire network.
•Requires more cable than the other topologies.
•More expensive due to the cost of the hub/switch.
•Bus Topology
Layout:
•All computers and devices are connected to a single central cable (called bus).
•The bus is a physical cable that connects the computers and other devices.
•Terminators are required at both ends of the backbone cable.
Data Transfer:
•Data transmitted on a bus network travels along the bus in both directions.
•When a sending device transmits data, the address of the receiving device is included with the transmission so that the data is sent to the appropriate receiving device.
•If the device address does not match the intended address for the data, the device ignores the data.
•If the data address match the device address, the data is accepted.
Advantages:
•Easy and inexpensive to set up.
•Adding and removing nodes can be done without disturbing the rest of the network.
•Failure of one node does not affect the rest of the network.
Disadvantages:
•Failure of the central cable will shut down the entire network.
•Only suitable for small size network.
•Data collision may occur because data transmitted will travel in both directions.
CLASSIFICATIONS OF NETWORKS
•Metropolitan Area Network (MAN)
a high-speed network that connects local area networks (LAN) in a metropolitan area such as a city or town
Usually managed by a consortium of users or by a single network provider that sells the service to the users.
•Example of MAN:
–Traffic light system in a city
•Wide Area Network (WAN)
Involve many types of transmission media such as telephone lines, cables, or radio waves
owned by a group of organizations including network service providers which provides network services
a network that covers a large area such as a country or the world
•Example of WAN
:
•The Internet (the biggest WAN)
•Local Area Network (LAN)
a network that connects computers and devices in a small area such as a home, school computer lab, office building or closely located buildings
owned by a single organization, such as school, college, university or company
used to link computers and to share expensive devices such as laser printer and file server
•Example of LAN:
–A network that connects computers on three floors in an office building.
•A wireless LAN (WLAN) is LAN that uses radio signals to connect computers and other devices
