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Chapter 1: Explore The Network : - Coggle Diagram
Chapter 1:
Explore The Network
:
COMPUTER NETWORKS
DEFINITION
Chain of interconnected computers
A number of computers connected together for the purpose of communication of processing
A network is a set of devices (nodes) connected by media
links
• A network is a group of computers and other devices (such as
printers) that are connected by some type of transmission media
• A network can be as small as two computers connected by a cable
in a home office or as large as several thousand computers connected across the world via a combination of cable,phone lines, and cellular links.
• They might communicate through copper wires, fiber-optic cable,
or radio waves as transmission media.
HOW NETWORKING TECHNOLOGIES ARE CHANGING THE HOME ENVIRONMENT.
Learn
Communicate
Work
Play
ADVANTAGES
• Networks enable multiple users to share resources
• Saves money.
• Saves time.
• Network allow you to manage, or administer, resources on
multiple computers from a central location.
DISADVANTAGES
Network Hardware, Software and Setup Costs
Hardware and Software Management and Administration Costs
Undesirable Sharing
Illegal or Undesirable Behaviour
Data Security Concerns
HOW HOST DEVICES CAN BE USED AS CLIENT, SERVER, OR BOTH
Client:
• A computer on the network that requests resources or services from another computer on a network.
Server:
• A computer on the network that manages shared resources.
Workstation:
• A personal computer (such as a desktop or laptop), which may or may not be connected to a network; most clients are
workstation computers.
Network Interface Card (NIC):
• The device inside a computer that connects a computer to the network media
Network Operating System (NOS):
• The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other
networking functions.
Host:
• A computer that enables resource sharing by other computers on the same network.
Node:
• A client, server, or other device that can communicate over a network and that is identified by a unique number, known as its
network address.
Connectivity Devices:
• A specialized device that allows multiple networks or multiple parts of one network to connect and exchange data.
Backbone:
• The part of a network to which segments and significant shared devices (such as routers, switches, and servers) connect.
Segment:
• A part of a network. Usually, a segment is composed of a group of nodes that use the same communications channel for all their
traffic.
Topology:
• The physical layout of a computer network. Topologies vary according to the needs of the organization and available hardware and expertise.
Protocol:
• A format for communication between networked devices.
Transmission Media:
• The means through which data are transmitted and received.
FUNDAMENTALS OF NETWORK MODELS
Peer-To-Peer Networks
ADVANTAGES
Easy to set up
Less complexity
Lower cost since network devices
Can be used for simple task such as transferring files and sharing printers
DISADVANTAGES
No centralized administration
Not as secure
Not scable
-All devices may act as both clients and servers which can show their performance
Client/Server Networks
• Another way of designing a network is to use a central computer, known as a server; to facilitate communication and resource sharing between other computers on the network, which are known as clients.
• A network that uses a server to enable clients to share data, data storage space, and devices is known as a client/server network.
• A client/server architecture is sometimes used to refer to the design of a network in which clients rely on servers for resource sharing and processing.
HOW LANs AND WANs INTERCONNECTING TO THE INTERNET
NETWORKS OF MANY SIZES
Small home networks
Small office/home office networks
Medium to large networks
World wide networks
TYPES OF NETWORKS
TWO MOST COMMON
Local area network (LAN)
Wide area network ( WAN)
LANs separated by geographic distance are connected by a network known as a WAN.
OTHER TYPES
Metropolitan area ( MAN)
Wireless LAN ( WLAN)
Storage Area Network (SAN)
Personal Area Network (PAN)
THE INTERNET
LANs use WAN services to interconnect.
Home LAN
Branch LAN
Government LAN
Enterprise LAN
School LAN
Internet is connecting a computer to any other computer
anywhere in the world via dedicated routers and servers.When two computers are connected over the Internet, they can send and receive all kinds of information such as text, graphics, voice, video, and computer programs.
The World
Extranet
Suppliers, Customers, Collaborators
DIFFERENT BETWEEN EXTRANET AND INTRANET
a. Extranet
shared content accessed by groups through cross-enterprise boundaries
b. Intranet
shared content accessed by members within a single organization
Intranet
Company only
FOUR BASIC REQUIREMENTS OF A RELIABLE NETWORK.
FAULT TOLERANCE
The Internet is always available to the
millions of users who rely on it.This requires a network
architecture that is built to be fault tolerant. One that limits the effect of a failure, so that the fewest number of devices are affected by it. Built in a way that enables quick recovery when such a failure occurs s depend on multiple paths between the
source and destination of a message. If one path fails, the
messages can be instantly sent over a different link. Having multiple paths to a destination is known as redundancy.
SCABILITY
Thousands of new users and service providers connect to the
Internet each week. In order for the Internet to support this
rapid amount of growth, it must be scalable.Can expand quickly to support new users and applications without affecting the performance of the service being delivered to existing users.
QUALITY OF SERVICE
Quality of service is also an ever-increasing requirement of
networks today. New applications available to users over internetworks, such as voice and live video transmissions.
SECURITY
Securing a network infrastructure includes physically securing
devices that provide network connectivity, and preventing unauthorized access to the management software that resides
on those devices.