Explore The Network, Explore The Network 1.3 Interpret reference model…
Explore The Network
4 Basic Requirement Of A Reliable Network
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.
requires a network
architecture that is built to be fault tolerant
A fault-tolerant network is one that limits the effect of a failure, so that the fewest number of devices are affected by it
built in away that enables quick recovery when such a failure occurs.
Fault-tolerant networks 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.
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.
How Networking Technologies are changing the home enviroment
Advantage of Computer Network
Networks enable multiple users to share resources (devices and data)
Network allow you to manage, or administer, resources on multiple computers from a central location.
Disadvantage of computer network
Network Hardware, Software and Setup Costs
Hardware and Software Management and Administration Costs
4.Illegal or Undesirable Behaviour
Data Security Concerns
Networks support the way we :
HOW LAN AND WAN INTERCONNECT TO THE INTERNET
Small Home Networks
Small Office/Home Office Networks
Medium to Large Networks
World Wide Networks
Types of Networks
Local Area Network (LAN)
Wide Area Network (WAN)
Metropolitan Area Network (MAN)
Wireless LAN (WLAN)
Storage Area Network (SAN)
Personal Area Network (PAN)
Extranet and Intranet
-Shared content accessed by groups through cross-enterprise boundaries.
-Shared content accessed by members within a single organization
Define the Computer Network
Computer Network Definition
“A number of computers connected together for the
purposes of communication of processing” – Knott, Waites and Callaghan, Comp. Studies
“A network is a set of devices (nodes) connected by media links” – Forouzan, Data Communications and Networking
“Chain of interconnected computers” –Oxford Dictionary
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.
Describe how host devices can be used as clients, server, or both.
Client/Server Network Element
Network Interface Card (NIC)
Network Operating System (NOS)
:check: A computer on the network that requests resources or services from another computer on a network.
:check: In some cases, 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.
:check: A computer on the network that manages shared resources.
:check: Servers usually have more processing power, memory, and hard disk space than clients.
:check: Server run network operating software that can manage not only data, but also users, groups, security, and applications on the network.
:check: 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)
:check: The device inside a computer that connects a computer to the network media
:check: Thus allowing it to communicate with other computers
Network Operating System (NOS)
:check: The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions.
:check: Ex: Microsoft Windows Server 2008 R2, Mac OS X Server, Unix and Linux OS.
:check: A computer that enables resource sharing by other computers on the same network.
:check: 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.
:check: A specialized device that allows multiple networks or multiple parts of one network to connect and exchange data.
:check: The part of a network to which segments and significant shared devices (such as routers, switches, and servers) connect.
:check: A backbone is sometimes referred to as “a network of networks” because of its role in interconnecting smaller parts of a LAN or WAN.
:check: 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.
:check: The physical layout of a computer network. Topologies vary according to the needs of the organization and available hardware and expertise.
:check: Networks can be arranged in a ring, bus, or star formation, and the star formation is the most common.
:check: Hybrid combinations of these patterns are also possible.
:check: A format for communication between networked devices.
:check: For example, some protocols ensure that data are transferred in sequence and without error from one node on the network to another.
:check: The means through which data are transmitted and received.
:check: Transmission media may be physical, such as wire or cable, or atmospheric (wireless), such as radio waves.
Fundamental of network models
Peer-to-Peer Networks (P2P)
Peer-to-Peer Networks (P2P)
:check: Easy to set up
:check: Less complexity
:check: Lower cost
:check: Can be used for simple task such as transferring file and printer
:check: No centralized administration
:check: Not as secure
:check: Not scalable
:check: All device may act as both clients and servers which can slow their perfomance
:check: 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.
:check: A network that uses a server to enable clients to share data, data storage space, and devices is known as a client/server network.
:check: 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.
Explore The Network
Interpret reference model of OSI and TCP/IP
Types of rules that are necessary to successfully communicate.
Main elements of data communication system
It is the information to be communicated. Popular forms of information include text, pictures, audio, video and etc.
It is the device which receives the data messages. It can be a
computer, workstation, telephone handset etc.
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.
It is the device which sends the data messages. It can be a computer, workstation, telephone handset and etc.
It is a set of rules that governs the data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating.
(Message Source) -> (Transmitter) -> (Transmission Medium) -> (receiver) -> (Message Destination)
Relationship between the Five Components
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 delivery options
Message Formatting and Encapsulation
1 . Message Encoding
Encoding between hosts 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 depending on the network media
The destination host receives and decodes the signals in order to interpret the message.
Message Formatting and Encapsulation
There is an agreed format for letters and addressing letters which is required for proper delivery.
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.
A frame acts like an envelope providing destination address and source address.
Humans break long messages into smaller parts or sentences.
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.
Hosts on a network need to know when to begin sending messages and how to respond when collisions occur.
Source and destination hosts use flow control to negotiate correct timing to avoid overwhelming the destination and ensure information is received.
Hosts on the network have rules that specify how long to wait for responses and what action to take if a response timeout occurs.
5 . Message Delivery Options
one - to - one delivery
One - to - many delivery
One - to - all delivery
Message sources are people, or electronic devices, that need to communicate a message to other individuals or devices.
The destination receives the message and interprets it.
Provides the pathway over which the message can travel from source to destination.
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
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
7) Application -
contains protocols used for process-to- process communications.
6) Presentation -
provides for common representation of the data.
5) Session -
provides services to the presentation layer to
organize its dialogue and to manage data exchange.
4) Transport -
defines services to segment, transfer, and reassemble the data.
3) Network -
provides services to exchange the individual pieces of data over the network between identified end
2) Data Link -
provides methods for exchanging data frames between devices over a common media.
1) Physical -
describes the mechanical, electrical,functional, and procedural means to transmit bits across physical connections.
The 7 Layers of OSI
The TCP/IP Protocol Model
Also called The TCP/IP Model or the Internet Model.
Created in the early 1970s for internetwork
OSI Model and TCP/IP Model Comparison
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
Combine 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
Why protocols are necessary in tetwork communication ?
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
1 . 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)
Grammar and sentence structure
Speed and timing of delivery
Networking protocols define 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).
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
example of an interaction between several protocols
- an application protocol that governs the way a web server and a web client interact.
- transport protocol that manages
the individual conversations.
– encapsulates the TCP segments into packets, assigns addresses, and delivers to the destination host.
- 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.
:check: 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.
:check: ARPANET was funded by the
U.S. Department of Defense for use by universities and research laboratories.
TCP/IP Protocol Suite
Network Access Layer
TCP/IP Communication Process
Sending data from a web server to a client
:check: Hypertext Markup Language (HTML) page. The HTTP application layer protocol sends the data to the transport layer.
:check: The transport layer breaks the data
into segments and identifies each.
:check: and destination addresses are added, creating an IP Packet.
:check: Ethernet information is then added creating the Ethernet Frame, or data link frame
TCP/IP Communication Process (Cont.)
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
:check: First the Ethernet header is removed
:check: Then the IP header
:check: Then the Transport layer header
:check: Finally the HTTP information is processed and sent to the client’s web browser
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