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CHAPTER 1 : EXPLORE THE NETWORK, Syazwan, shahrul - Coggle Diagram
CHAPTER 1 : EXPLORE THE NETWORK
1.1.4 HOW LANs AND WANs INTERCONNECT TO THE INTERNET
:
Networks of Many Sizes:
Small home networks
Small office/home networks
Medium to large networks
World wide networks
Types of Networks
The two most common types of network infrastructures are:
Local Area Networks
Wide Area Networks
LANs separated by geographic distance are connected by a network known as a WAN
Other types of networks include:
Metropolitan Area Network (MAN)
Wireless LAN (WLAN)
Storage Area Network (SAN)
Personal Area Network (PAN)
The Internet
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
Intranets and Extranets
Different between Extranet and Intranet
Extranet
shared content accessed by groups through cross-enterprise boundaries
Intranet
shared content accessed by members within a single organization
1.3 Intepret reference model of OSI and TCP/IP
1.3.1 Describe the types of rules that
are necessary to successfully communicate
Main elements of data communication systems
Message
- It is the information to be communicated. Popular forms of information include text, pictures,audio,video, and etc
Sender
- It is the device which sends the data messages.It can be a computer,workstation,telephone handset and etc
Receiver
- It si the device which receives the data messages.It can be a computer, workstation,telephone handset etc
Transmission medium
- It is the physical path by which a message travels from sender to receiver.Some examples include twisted-pair wire,coaxial cable,radio waves and etc.
Protocol
- It is set of rules that governs the data communications. It represents an agreement between the communication devices. Without a protocol,two devices may be connected but not communicating
Rule Establishment
Protocols used in network communications also define:
Message encoding
◦ Message delivery options
◦ Message Formatting and Encapsulation
◦ Message Timing
◦ Message Size
Protocols are necessary for effective communication and include:
◦ An identified sender and receiver
◦ Common language and grammar
◦ Speed and timing of delivery
◦ Confirmation or acknowledgment requirements
The Rules
Message Encoding
Each bit is encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media
The destination host receives and decodes
the signals in order to interpret the message
Messages are first converted into bits by
the sending host.
Encoding between hosts must be in
appropriate format for the medium.
Message Formatting and Encapsulation
Putting the letter into the addressed envelope
is called encapsulation
Each computer message is encapsulated in a
specific format, called a
frame
, before it is sent over the network.
There is an agreed format for letters and
addressing letters which is required for proper delivery.
A
frame
acts like an envelope providing
destination address and source address.
Message Timing
Access Method
Hosts on a network need to know when to begin
sending messages and how to respond when collisions occur.
Flow Control
Source and destination hosts use flow control to
negotiate correct timing to avoid overwhelming the destination and ensure information is received..
Response Timeout Hosts on the network have rules that specify how long
to wait for responses and what action to take if a response timeout occurs.
Communication methods
Source (Sender) - Message sources are people, or electronic
devices, that need to communicate a message to other individuals or devices
Destination (Receiver) - The destination receives the message
and interprets it.
Channel (Media) - Provides the pathway over which the message
can travel from source to destination.
1.3.2 Why protocols are necessary in network communication
Protocol suites are implemented by
hosts and networking devices in software, hardware or both.
The protocols are viewed in terms of
layers, with each higher level service depending on the functionality defined by the protocols shown in the lower levels.
Among the protocols for successful human
communication are:
Identification of sender and receiver
Agreed-upon medium or channel (face-to-face,telephone, letter, photograph)
Appropriate communication mode (spoken, written,illustrated, interactive or one-way)
N
etwork Protocols:
Define a common format and set of rules for exchanging messages between devices.
The role of protocols
How the message is formatted or structured
The process by which networking devices share information about pathways with other networks
How and when error and system messages are passed between
devices
The setup and termination of data transfer sessions
Protocol Interaction
HTTP
- an application protocol that
governs the way a web server and a web client interact.
TCP
- transport protocol that manages
the individual conversations.
IP
– encapsulates the TCP segments
into packets, assigns addresses, and delivers to the destination host.
Ethernet
- allows communication over
a data link and the physical transmission of data on the network
media
Protocol Suites and Industry Standards
A protocol suite is a set of
protocols that work together to provide comprehensive network
communication services.
May be specified by a standards
organization or developed by a
vendor.
Development of TCP/IP
Advanced Research Projects
Agency Network (ARPANET) was the predecessor to today’s
Internet.
TCP/IP Communication Process
When sending data from a web
server to a client the encapsulation procedure would be as follows:
The webserver prepares the Hypertext Markup Language (HTML)page. The HTTP application layer protocol sends the data to thet transport layer.
The transport layer breaks the data
into segments and identifies each.
The Ethernet information is then
added creating the Ethernet Frame,or data link frame.
◦ Next the IP source and destination
addresses are added, creating an IP Packet
TCP/IP Communication Process (Cont.)
First the Ethernet header is
removed
Then the IP header
◦ Then the Transport layer header
Finally the HTTP information is
processed and sent to the client’s web browser
1.3.3 How the TCP/IP model and the OSI model are used to facilitate standardization in the communication process
The benefits of using a
layered model include:
Fostering competition because
products from different vendors can work together
◦ Preventing technology changes
in one layer from affecting other layers.
◦ Assisting in protocol design
since protocols at each layer have defined functions
◦ Providing a common language
to describe networking functions and capabilities.
The OSI Reference Model
Transport - defines services to segment, transfer, and
reassemble the data
Network - provides services to exchange the individual
pieces of data over the network between identified end devices
Session - provides services to the presentation layer to
organize its dialogue and to manage data exchange
Data Link - provides methods for exchanging data frames
between devices over a common media.
Presentation - provides for common representation of
the data.
Physical - describes the mechanical, electrical,
functional, and procedural means to transmit bits across physical connections
Application - contains protocols used for process-toprocess communications
The TCP/IP Protocol
Model
◦ Created in the early
1970s for internetwork
communications.
OSI Model and TCP/IP Model Comparison
In the OSI model, the
network access layer and the application layer of
the TCP/IP model are further divided to
describe discrete functions that must occur
at these layers.
1.1.5 FOUR BASIC REQUIREMENTS OF A RELIABLE NETWORK
Fault Tolerance
A fault-tolerant network is one that limits the effect of a failure, so that the fewest number of devices are affected by it.
It is also built in a way that enables quick recovery when such a failure occurs.
Fault-tolerant networks depend on multiple paths between the source and destination of a message.
Scalability
A scalable network 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
preventing unauthorized access to the management software that resides on those devices.
WAN AHMAD
TOPIC 1.1.1 COMPUTER NETWORK DEFINITION
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 large as several thousand computer 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.
TOPIC 1.1.2 : HOW NETWORKING TECHNOLOGIES ARE CHANGING THE HOME ENVIROMENT.
No Boundaries
Networks support the way we:
Learn
Communicate
Work
Play
ADVANTAGES OF COMPUTER NETWORK
Networks enable multiple users to share resources (devices and
data).
Saves money.
Saves time.
Network allow you to manage, or administer, resources on
multiple computers from a central location.
DISADVANTAGES OF COMPUTER NETWORK
Network Hardware, Software and Setup Costs
Hardware and Software Management and Administration Costs
Undesirable Sharing
Illegal or Undesirable Behaviour
Data Security Concerns
TOPIC 1.1.3 : HOW HOST DEVICES CAN BE USED AS CLIENT, SERVER OR BOTH.
Client / Server Element :
Client :
A computer on the network that requests resources or services
from another computer on a network.
In some cases, a client could also act as a server
Server :
A computer on the network that manages shared resources.
Servers usually have more processing power, memory, and hard disk space
than clients.
Server run network operating software that can manage not only data, but
also users, groups, security, and applications on the network
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.
Thus allowing it to communicate with other computers
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.
A backbone is sometimes referred to as “a network of networks” because of its role in interconnecting smaller parts of a LAN or WAN.
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.
Networks can be arranged in a ring, bus, or star formation, and the star formation is the most common.
Hybrid combinations of these
patterns are also possible.
Protocol :
A format for communication between networked devices.
For example, some protocols ensure that data are transferred in sequence and without error from one node on the network to another.
Transmission Media :
The means through which data are transmitted and and received.
Transmission media may be physical, such as wire or cable, or atmospheric (wireless), such as radio waves.
Fundamentals Of Network Model
PEER TO PEER NETWORK ( P2P )
The Advantage of Peer To Peer Networking (P2P)
Easy to set up
Less complexity
Lowest cost since network devices and dedicated server may not required
Can be used for simple task such as transferring and sharing printers.
The Disadvantage of Peer To Peer Networking
No centralized administration.
Not as secure.
Not scalable
All devices may act as both clients and server which can slow their performance.
Client / Server Network
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.
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