EXPLORE THE NETWORK
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Rules that are necessary to succesfully communicate
Cleagean G.
Firdaus Musa
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Stephen A.
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Afif Asyraf
Explain LANs, WANs and The Internet
Communication fundamentals
1.3.3
Computer Networks Definition
Computer communication
Message source>Transmitter>Transmission medium>Receiver>Message destination
assisting in protocol design
fostering competition
preventing technology
providing a common language
Main element of data communication system
Message - Information that is communicated. Such as text, pictures, audio, video and etc.
The OSI reference model
“Chain of interconnected computers” –Oxford Dictionary
“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
Application
Sender - Device that sends data, Such as a computer,
workstation, telephone handset and etc.
Presentation
provides for common representation of
the data
Receiver - Device that receives data. Such as a
computer, workstation, telephone handset etc.
Session
provides services to the presentation layer to
organize its dialogue and to manage data exchange
Transport
contains protocols used for process-toprocess communications
Transmission medium - Physical path for message to travel from sender to receiver. Such as twisted-pair wire, coaxial cable,
radio waves and etc.
defines services to segment, transfer, and
reassemble the data
Network
Protocol - Set of rules of data communication. Without protocols, two device may not be communicating
provides services to exchange the individual pieces of data over the network between identified end devices
Rule establishment
Data Link
Protocols are necessary for effective communication and include:
Physical
provides methods for exchanging data frames
between devices over a common media
describes the mechanical , electrical , functional and procedural means to transmit bits across physical connections
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
Message Encoding
Encoding between hosts must be in
appropriate format for the medium. Messages are first converted into bits by
the sending host.
Message Formatting and Encapsulation
Agreed format for letters and addressing letters
which is required for proper delivery
Putting letters in envelope is encapsulation
Each encapsulated data is stored in a specific format
Rules
Computer Network
Message size message size is broken into smaller parts
Message timing appropriate time, appropriate timing and appropriate sign out
A network is a group of computers and other devices (such as printers) that are connected by some type of transmission media
Message delivery option: unicast message , multicast message, broadcast message
can be as small as two computers connected by a cable in a home office or as large as (more than two thousand) computers connected across the world via a combination of cable, phone lines, and cellular links
Communication method has 3 elements in common: source (sender), destination (receiver), channel (media)
they might communicate through copper wires, fiber-optic cable, or radio waves as transmission media
message
message
message
segment
Why protocols are necessary in network communication
packet
Rules
Protocol are implemented by hosts. Protocols are viewed in layers. Which lower services is defined by lower services
Communication protocols that are succesful
-Known sender and receiver -Agreed medium - Appropriate communication -Common language -Timing
Networks protocols - Defined a common format or sets of rules
Common network protocols are HTTP, TCP, IP
Protocol interaction Communication between a web server and a web client
Advantages
Disadvantages
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
Network Hardware, Software and Setup Costs
Hardware and Software Management and Administration Costs
Undesirable Sharing
Illegal or Undesirable Behaviour
Data Security Concerns
Client/Server Network Elements
Client
Server
Workstation
Network Interface Card (NIC)
Network Operating System (NOS)
Host
Node
Connectivity Device
Backbone
Protocol
Transmission Media
How LANs and WANs
interconnect to the internet
- 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. The term client may also refer to the human user of a client workstation or to client software installed on the workstation.
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- 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.
- 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 of many sizes
Topology
- The device inside a computer that connects a computer to the network media
- Thus allowing it to communicate with other computers
HTTP - protocols that governs a web server and web client interact with each other
TCP - transport protocols that governs the individual conversation
- The software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions.
IP - encapsulates TCP segments into packets/assign address and delivers to communication hosts
- A computer that enables resource sharing by other computers on the same network.
Ethernet - allows communication over data link
Basic Requirements Of A Reliable Network
Protocol suites and industry standards - A set of protocols that works together to provide comprehensive network communication service
- 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.
One that limits the effect of a failure so that few number devices affected by it
- A specialized device that allows multiple networks or multiple parts of one network to connect and exchange data.
TCP/IP suite is an open standard and any vendor are able to implement these protocols on their hardware and software
- The part of a network to which segments and significant shared devices (such as routers, switches, and servers) connect.
- 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.
Scalability
Fault Tolerance
Security
Quality of Service
- The physical layout of a computer network. Topologies vary according to the needs of the organization and available hardware and expertise.
- A format for communication between networked devices.
- The means through which data are transmitted
Development of TCP/IP
Advanced Research Projects Agency Network is the predecessor of todays internet
TCP/IP
Communication services - when sending data from a web server to a client the encapsulation would be as follows: Web server prepares the HTML page > HTTP application layer protocol sends data to the transport layer > Transport layer breaks the data into segments and identifies each > IP source address is added, creating an IP packets > The ethernet info is then added creating the ethernet frame
Segment
Scalable network can expend
quickly to support new users
and applications without affecting
the service performance
delivered to existing user
Securing a network infrastructure include
physically securing devices that
provide network connectivity, preventing
unauthorized access to the software management
Communication services - when receiving data link frame form web servers, the client process and removes each protocol header in the opposite order it was added: Ethernet header is removed > IP header removed > Transport layer header removed > The HTTP information is processed and sent to the client web browser
Fundamental of network models
Peer-to-Peer (P2P)
Client/Server Networks
bit
frame
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The TCP/IP Protocol
Model
created in the early 1970s internetwork communications
Advantages
Disadvantages
open standard
also called the TCP/IP Model or the internet model
Less complexity
TCP/IP MODEL
Easy to set up
application
internet
transport
Lower cost since network devices and dedicated servers may not be required
network access
represents data to the user, plus encoding and dialog control
control the hardware devices and media that make up the network
determines the best path through the network
supports communication between diverse devices across diverse networks
Can be used for simple tasks such as transferring files and sharing printers
TCP/IP Protocol Suite
HTTP, DNS, DHCP, FTP
•Small Home Network
•Home Office Network
•Medium to Large Network
•World Wide Network
No centralized administration
Not as secure
Not scalable
All devices may act as both clients and servers which can slow their performance
Type of 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.
•Metropolitian Area Network
•Wireless LAN
•Storage Area Network
•Personal Area Network
OSI model
TCP/IP model
application
application presentation session
transport
Internet
Intranet
Extranet
network
data link
physical
shared content accessed by groups through
cross- enterprise boundaries
transport
internet
network access
TCP, UDP
IPv4, IPv6, ICMPv4, ICMPv6
PPP, Frame Relay, Ethernet
shared content accessed by members within
a single organization
Model comparison
connecting a computer to any computer
anywhere in the world via routers and servers
Similarities
Differences
share similar
architecture
share a common
application layer
both models have comparable transport and network layers
Local Area Network 
knowledge of both models is required by networking professionals
Protocol standard
combines the presentation and session layer issues into its application layer
Wide Area Network 
combines the OSI data link and physical layers into the network access layer
a simpler model
