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Explore The Network, Interpret Reference model of OSI and TCP/IP - Coggle…
Explore The Network
How LANs and WANs
interconnect to the Internet
Types of Network
Local Area Network (LAN)
Wide Area Network (WAN)
Metropolitan Area Network (MAN)
Wireless LAN (WLAN)
Storage Area Network (SAN)
Personal Area Network (PAN)
Intranet
Shared content accessed by groups through cross-enterprise boundaries
Extranet
shared content accessed by members within a single organization
Internet
Internet is connecting a computer to any other computer
anywhere in the world via dedicated routers and servers
4 basic
requirements of a reliable network
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 (QoS)
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.
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.
Security
Physically securing
devices that provide network connectivity
preventing
unauthorized access to the management software that resides
on those devices
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 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 enviroment
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
Undesirable Sharing
Illegal or Undesirable Behaviour
Hardware and Software Management and Administration Costs
Data Security Concerns
How host devices can be
used as clients, server, or both
Client/Server Network Elements
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 Device
A specialized device that allows multiple networks or multiple
parts of one network to connect and exchange data
Host
A computer that enables resource sharing by other computers
on the same network
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
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
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
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
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
Workstation
A personal computer
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
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
Transmission Media
The means through which data are transmitted
and received
Transmission media may be physical, such as wire or cable,
or atmospheric (wireless), such as radio waves
Client
A computer on the network that requests resources or services
from another computer on a network
a client could also act as a server. The term client may also refer
to the human user of a client workstation or to client software installed on the
workstation
Fundamental of network models
Peer-to-Peer
Networks (P2P)
Advantages
Easy to set up
Less complexity
Lower cost since network devices and dedicated servers may not be required
Can be used for simple tasks such as transferring files and sharing printers
Disadvantages
Not as secure
Not scalable
No centralized administration
All devices may act as both clients and servers which can slow 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
Interpret Reference model of OSI and TCP/IP
Rule Establishment
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
Protocols used in network communications also define:
◦ Message encoding
◦ Message delivery options
◦ Message Formatting and Encapsulation
◦ Message Timing
◦ Message Size
The Rules
Message Encoding
Must be in
appropriate format for the medium.
Messages are first converted into bits by
the sending host.
Each bit is encoded into a pattern of sounds, light waves, or electrical impulses
The destination host receives and decodes the signals in order to interpret the message
Message Formatting and Encapsulation
An agreed format for letters and
addressing letters which is required for proper delivery
Putting the letter into the addressed envelope
is called encapsulation
Encapsulated in a
specific format, called a frame before it is
sent over the network
A frame acts like an envelope providing
destination address and source address.
Message Size
Long messages must also be broken into smaller
pieces to travel across a network
◦ Each piece is sent in a separate frame.
◦ Each frame has its own addressing information.
◦ A receiving host will reconstruct multiple frames into the original message.
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.
Message Delivery Options
Unicast Message
One-to-one delivery
Multicast Message
One-to-many delivery
Broadcast Message
One-to-all delivery One-to-one delivery
Communication Fundamentals
Message: information to be communicated
Include text, pictures, audio, video and etc.
Sender: sends the data messages
Computer,
workstation, telephone handset and etc.
Receiver: receives the data messages
Computer, workstation, telephone handset etc
Transmission Medium: physical path by which a message travels from
Twisted-pair wire, coaxial cable,
radio waves and etc
Protocol: rules that governs the data communications.
. Without a
protocol, two devices may be connected but not communicating
Rules that Govern Communications
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)
Common language
Grammar and sentence structure
Speed and timing of delivery
Network Protocols
A common format and set of rules for exchanging messages
between devices.
Some common networking protocols are Hypertext Transfer Protocol (HTTP), Transmission Control Protocol (TCP), and Internet Protocol (IP)
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
Communication between a web server and web client is an example of an interaction between several protocols:
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
The TCP/IP protocol suite is an open standard, the protocols are freely available, and any vendor is able to implement these able to implement these protocols on their hardware or in their software.
TCP/IP Communication Process
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 the transport layer.
◦ The transport layer breaks the data into segments and identifies each.
◦ Next the IP source and destination addresses are added, creating an IP Packet
◦ The Ethernet information is then added creating the Ethernet Frame, or data link frame.
◦This frame is delivered to the nearest router along the path towards the web client. Each router adds new data link information before forwarding the packet
When receiving the data link frames from the web server, the client processes and removes each protocol header in the opposite order it was added:
◦ 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
The Benefits of Using a Layered Model
◦ Assisting in protocol design since protocols at each layer have defined functions.
◦ Fostering competition because products from different vendors can work together.
◦ Preventing technology changes in one layer from affecting other layers.
◦ Providing a common language to describe networking functions and capabilities.
The OSI Reference Model
Application - contains protocols used for process-to-process communications.
Presentation - provides for common representation of the data.
Session - provides services to the presentation layer to organize its dialogue and to manage data exchange.
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
Data Link - provides methods for exchanging data frames between devices over a common media.
Physical - describes the mechanical, electrical, functional, and procedural means to transmit bits across physical connections.
The TCP/IP Protocol
Model
◦ Created in the early 1970s for internetwork communications
◦ Open Standard.
◦ Also called The TCP/IP Model or the Internet Model.
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.
Similarities
Share similar
architecture.
Share a common
application layer
Both models have comparable transport and network layers.
Knowledge of both models is required by networking professionals
Differences
Protocol standard
Combines the presentation and session layer issues into its application layer
Combines the OSI data link and physical layers into the network access layer
A simpler model
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.