communication and networking parallel and distributed computing

Introduction
to
Computer NetworkWeek 01

Outline
Overview of Computer Networks
Network Protocols
OSI and TCP/IP Model
Role of Protocols in Networks

Scope
Networks support the way we learn.
Networks support the way we communicate.
Networks support the way we work.
Networks support the way we play.
Networking is Everywhere

COMPUTER NETWORK
A COMPUTER NETWORK IS A SET OF NODES CONNECTED BY COMMUNICATION LINKS.

Node?
A NODE can be a computer, printer or any other device capable of sending/receiving data
generated by other nodes in the network.
printer
server
security
camera
Capable of
sending/rece
iving data
computer
switches
Any other
device

Nodes
Examples of NODE
Computer
Server
Printer
Security camera
Other devices (Switches, Bridges, Routers
etc.)

COMMUNICATION LINK
A link is a communication channel that connects two or more devices for the purpose of
data transmission.

Wireless link
Wired link
COMMUNICATION LINKS
A Communication link can be a wired link or wireless link
The link carries the information

links
Links (medium) Wired: Cable
Wireless: Air

Example of computer
network
Resource
sharing

communication and networking parallel and distributed computing

Activity time
Find out the end nodes (end devices) and intermediary nodes depicted in the
scenario and place them rightly.
END DEVICES INTERMEDIATE NODES

Activity time
Find out the end nodes (end devices) and intermediary nodes depicted in the
scenario and place them rightly.
END DEVICES INTERMEDIATE NODES
PC Router
Printer Wireless
Server Cell tower
Tablet Modem
Smart phone Internet cloud

Characteristics of
Computer Network
we are going to discuss some basic characteristics of Computer Networks.

Basic characteristics of
computer network
Fault tolerance
Scalability
Quality of service (QoS)
security

Fault tolerance
Its the ability to
Continue working despite of failure
Ensure no loss of service

Fault tolerance
Fault tolerance in computer networks is like
having a backup plan for when things go
wrong. It's all about designing a network
that can keep running smoothly even if
some parts of it fail

Fault tolerance - network
Why is it Important?
In today's interconnected world, network downtime can have
serious consequences.
It can lead to:
•Loss of productivity: If a business network goes down,
employees can't access critical systems and data, leading to lost
time and revenue.
•Disruption of services: Network outages can interrupt essential
services like healthcare, transportation, and emergency response.
•Damage to reputation: Frequent network failures can erode trust
and damage an organization's reputation

SCALABILITY
What is Network Scalability?
Network scalability refers to the ability of a
network or system to handle a growing
amount of change and its potential to be
enlarged to accommodate that growth.

Scalability
 Its the ability to
Grow based on the needs
Have good performance after growth

Scalable network – the
internet

Security is protection from, or resilience
against, potential harm (or other unwanted
coercion).
It is the practice of protecting a network from
unauthorized access, misuse, or attacks. It
involves using tools, technologies, and policies
to keep data safe.
SECURITY

Security
The ability to prevent
Unauthorized access
Misuse
Forgery
the ability to provide
Confidence
Integrity
availability

QoS
A set of technologies that manage network
traffic by prioritizing specific data flows,
ensuring that critical applications receive the
necessary bandwidth and performance even
under limited network capacity, effectively
guaranteeing a certain level of service for
high-priority applications and users

Quality of service (QOS)
The ability to
Set priorities
Manage data traffic to reduce data loss, delay etc.

• Prioritization:
QoS allows network administrators to assign different priority levels to various types of traffic, like voice
calls, video streaming, and regular data transfer, ensuring that essential applications receive preferential
treatment.
• Traffic management techniques:
Mechanisms like queuing, classification, policing, and marking are used to manage data flow and
prioritize specific traffic types.
• Performance metrics:
QoS is measured by factors such as packet loss, latency, jitter, and throughput, which are used to assess
the overall quality of network service.
• Application scenarios:
QoS is particularly important for applications that require real-time performance, such as video
conferencing, online gaming, and telephony, where consistent low latency and minimal packet loss are
crucial.
Key points of QOS

Data
communication
Data flow and Protocols

Data communication
 Data communications
are the exchange of
data between two
nodes via some form
of link (transmission
medium) such as a
cable.

Transmission Modes
 Transmission modes define the direction of data transmission, it defines the direction
of the flow of information between two communication devices.
 Every data transmitted on the communication channel has a direction and this
direction between two communication devices is defined by data transmission modes.
 Also referred to as Data Communication mode or Directional mode.
Three types of Transmission mode
Simplex Mode
Half-Duplex Mode
Full-Duplex Mode

Data flow
Data Flow
(Transmission mode)
Full-Duplex
Half-Duplex
Simplex Duplex

Data flow - simplex
 Communication is always unidirectional
 One deceive can transmit and other deceive will receive
examples

Simplex
 In simplex mode, data can flow in only one direction, Unidirectional.
 In this mode, a sender can only send data but cant receive it similarly, a receiver can
only receive data but cant send it.
 It’s a one-way communication mode as it allows data to flow in only one direction, the
sender cannot receive any feedback or acknowledgment from receiver.
 Simplex mode is mostly used for broadcast communication, where one device sends
a message to multiple recipients, but the recipients cannot respond or send data
back.
 Examples : television broadcast transmitting a TV program to multiple viewers, a radio
station transmitting music to listeners.

Simplex
Advantages:
Simplex mode requires fewer resources, like bandwidth and processing power
Simple to implement and does not requires complex synchronization between sender
and receiver.
Disadvantages:
No Feedback
Limited Functionality
Inefficient for two-way communication.

Data flow – half duplex
 Communication is in both directions but not the same time
 If one device is sending, the other can only receive, and vise versa.
 Example : walkie talkie

Data flow – Half-Duplex
 In half-duplex mode, data can flow in both directions but in one direction
at a time
 Means when one node is sending the data, then the receiving node has
to wait.
 While one device is sending the other can only receive and vise versa
Transmitter/
Receiver
Transmitter/
Receiver
Half-Duplex
(Takes Turns)

Half-Duplex
Advantages:
 Its simpler to implement compared to full-duplex mode, as it does not require complex
synchronization between the sender and receiver.
 It requires a smaller bandwidth compared to full-duplex mode.
Disadvantages:
 Lack of simultaneous communication between the sender and the receiver can limit
the functionality of the communication system.
 Less efficient compared to full-duplex mode
 Need for a turn-taking mechanism can add overhead and latency to the
communication system.

Data flow – Duplex/Full-Duplex
 Communication is in both directions simultaneously
 Device can send and receive at the same time
 Example: telephone line

Data flow – Duplex/Full-Duplex
 Full-Duplex mode in computer networks is a type of data transmission in which data
can be transmitted in both directions simultaneously.
 This means that two device can send and receive data at the same time, without any
delay or waiting time.
 Full-Duplex mode is often used in local area networks (LANs), where multiple devices
need to communicate with each other simultaneously.
 In this system, each device has a dedication communication channel for sending and
receiving data. This allows for high-speed, high-bandwidth communication between
devices.
Transmitter/
Receiver
Transmitter/
Receiver
Full-Duplex
(transmit simultaneously)

Full-Duplex
Advantages:
 It allows data to be transmitted in both directions simultaneously, which increases the
efficiency and performance of the communication system.
 Its supports high-speed, high-bandwidth communication, making it suitable for
applications that require large amounts of data to be transmitted quickly.
 It eliminated the need for devices to take turns transmitting data, reducing the latency in
the communication system.
Disadvantages:
 Need more complex hardware and software, which increase the cost of the
communication system.
 Requires a larger bandwidth
 Increases the risk of collisions, where two devices transmit data at the same time and
data is lost.

Protocols
Computer Network Protocols

Protocols
Protocols = rules.
It is the set of rules that govern data communication
Protocol determines:
 What is communicated?
 How it is communicated?
 When it is communicated?

Protocols
All communication schemes will have the following things in common:
 Source or sender
 Destination or receiver
 Channel or media
Rules or protocols govern all methods of communication

Protocols – Human
Communications
 Protocols are necessary for human communication and include:
 An identified sender and receiver
 Common language and grammar
 Speed and timing of delivery
 Confirmation or acknowledgement requirements

Network Protocols
Network protocols are a set of rules outlining how connected
devices communicate across a network to exchange information
easily and safely.
Protocols serve as a common language for devices to enable
communication irrespective of differences in software, hardware,
or internal processes.

Protocols – network
communication
Protocols used in network communication also define:
 Message encoding
 Message formatting and encapsulation
 Message timing
 Message size
 Message delivery options

Elements of a protocol
 Message encoding
 Message formatting and encapsulation
 Message timing
 Message size
 Message delivery options

1. Message encoding
Message
Source
Encoder
(Signal)
Transmitter
Transmission
Medium
Receiver
Decoder
(Signal)
Message
destination

2. Message formatting and
encapsulation
The process of structuring a message with a specific format,
including headers containing relevant information like source
and destination addresses, and then "wrapping" that data
within additional layers of information to prepare it for
transmission across a network
Agreed format.
Encapsulate the information to identify the sender and the
receiver rightly.

3. Message size
Message size refers to the total amount of data contained within a single
message being transmitted, including the message header, body, and
any attached files, essentially defining the overall weight of the
information being sent across a network or communication channel; it is
often measured in bytes or kilobytes
Long messages must also be broken into smaller pieces to travel across
a network.

4. Message timing
Message timing refers to the precise moment a message is sent and received,
essentially dictating the speed at which data is transmitted across a network, ensuring
proper synchronization between devices and preventing data loss by managing when
and how much data can be sent at any given time.
 Manages Flow control
 Response timeout

5. Message delivery options
The different methods available to send data (messages) across a
network, including choices like unicast (one-to-one), multicast
(one-to-many), and broadcast (one-to-all), allowing you to specify
whether a message should be delivered to a single recipient, a
specific group of recipients, or all devices on the network,
respectively
Options:
 UNICAST
 MULTICAST
 BROADCAST

OSI and TCP/IP Model
Network protocols

OSI and TCP/IP Model
A network protocol is a set of rules that govern how data is
transmitted and received across a network, while the OSI
(Open Systems Interconnection) model and TCP/IP model
are conceptual frameworks that divide network communication
functions into distinct layers, providing a structured way to
understand how data flows through a network.
These models work as frameworks for organizing and
understanding how data moves from one device to another
across networks.

OSI Model
OSI stands for Open Systems Interconnection. It has 7 layers.
Each layer performs its task independently. It was developed
in 1984 by the International Organization for Standardization
(ISO).

TCP/IP Model
TCP/IP stands for Transmission Control Protocol/Internet
Protocol. It has 4 layers. It also can be used as a
communications protocol in a private computer network. It was
designed by Vint Cerf and Bob Kahn in the 1970s.

Role of Protocols in Network
Network protocols play a vital role in network design and
operation, as they define the rules and standards for
communication, and impact network performance, security,
and interoperability. Network designers must choose the
appropriate protocols for each type of communication, taking
into account the trade-off between reliability and speed,
security, and interoperability. By understanding the role of
network protocols in network design, network administrators
can ensure that their networks operate effectively and
efficiently.

"Computer networks:
Weaving a digital tapestry
that connects minds, bridges
distances, and empowers
the world."
I hope this has given you a good foundation in [topic]. I encourage you to explore this further.

communication and networking parallel and distributed computing

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