Computer Networks - Basic Characteristics

Summary

This computer networks course segment explores the fundamental characteristics of a robust network: fault tolerance, scalability, Quality of Service (QoS), and security. Fault tolerance ensures uninterrupted service despite failures, using alternate routes to maintain connectivity. Scalability allows networks to expand and maintain performance as new devices join. QoS prioritizes data traffic to minimize loss and delays, especially for real-time communications like VoIP. Security prevents unauthorized access and ensures the confidentiality, integrity, and availability of data, crucial for protecting sensitive information in transit. The lecture uses relatable examples to clarify these concepts, highlighting their importance in modern networking.

Takeaways

• 🌐 The session aims to understand the need for fault-tolerant, scalable, secure, and high-quality service networks.
• 🔄 Fault tolerance is the network's ability to continue functioning without loss of service despite failures.
• 🚀 An analogy for fault tolerance is finding an alternative route home when the usual path is blocked.
• 🌐 Scalability is the network's capacity to grow and maintain performance even after an increase in size or number of devices.
• 🌐 The Internet serves as a prime example of a scalable network, accommodating new devices continuously.
• 🚦 Quality of Service (QoS) is about setting priorities for data traffic to minimize data loss and delays.
• 📞 QoS is illustrated by prioritizing real-time voice communication over email data due to the sensitivity to delays in the former.
• 🔒 Security in computer networks involves preventing unauthorized access and ensuring confidentiality, integrity, and availability of data.
• 🛡️ Confidentiality ensures that data is only understandable by the sender and receiver, protecting it from eavesdroppers.
• 🛡️ Integrity ensures that data sent remains unaltered during transmission, maintaining the original message.
• 🛡️ Availability ensures that network resources are accessible and not defaced or made inaccessible by attackers.

Q & A

What are the four basic characteristics of a computer network?

The four basic characteristics of a computer network are Fault Tolerance, Scalability, Quality of Service (QoS), and Security.

What is Fault Tolerance in the context of computer networks?

Fault Tolerance is the ability of a computer network to continue working despite failures and ensuring there is no loss of service.

Can you provide an example to illustrate Fault Tolerance?

An example of Fault Tolerance is when a person cannot take their regular route home due to a blockage and instead finds an alternative route to reach home, similar to how a network reroutes traffic through alternative paths when a failure occurs.

Why is Fault Tolerance important in computer networks?

Fault Tolerance is important because it ensures that the network continues to function even when failures occur, thereby preventing loss of service.

How is Scalability defined in computer networks?

Scalability is the ability of a network to grow based on the needs and maintain good performance even after growth.

What is an example of a scalable network?

The Internet is an example of a scalable network because it can handle the addition of new devices and maintain its performance.

What does Quality of Service (QoS) mean in computer networks?

Quality of Service (QoS) refers to the ability to set priorities and manage data traffic to reduce data loss and delays.

Why is it important for a router to prioritize data in a network?

It is important for a router to prioritize data because different types of data have different sensitivity to delays. For example, real-time communication like voice-over IP requires lower latency compared to non-real-time data like email.

What is the role of Security in computer networks?

Security in computer networks is about preventing unauthorized access, misuse, or forgery, and ensuring confidentiality, integrity, and availability of data.

How does a network ensure the confidentiality of data being transmitted?

A network ensures the confidentiality of data by converting it into a form that is understandable only by the sender and the receiver, thus preventing unauthorized entities from accessing the original information.

What does Integrity in the context of network security mean?

Integrity in network security means that the data sent by the sender should not be modified during transmission, ensuring that the receiver gets exactly what was sent without any alterations.

Outlines

00:00

🔌 Fault Tolerance in Computer Networks

The first paragraph introduces the basic characteristics of computer networks, focusing on fault tolerance. Fault tolerance is defined as the network's ability to continue functioning despite failures, ensuring no loss of service. An analogy is made with finding an alternative route home when a regular path is blocked. An example of two entities communicating through various network components is given to illustrate how a fault-tolerant network reroutes data around a failure point, thus maintaining communication.

05:02

📈 Scalability and Quality of Service (QoS) in Networking

The second paragraph discusses scalability as the network's capacity to grow and maintain performance. The Internet is cited as an example of a scalable network, accommodating new devices continuously. The concept of Quality of Service (QoS) follows, which is about prioritizing data traffic to minimize data loss and delays. A scenario where a router must choose between processing email data and voice-over IP (VoIP) data is presented, highlighting that real-time communications like VoIP take priority due to their sensitivity to delays.

Keywords

💡Computer Networks

Computer Networks refer to a collection of interconnected devices that communicate with each other for the exchange of information. They are the backbone of modern communication, enabling data sharing and resource accessibility. In the video, the theme revolves around understanding the fundamental characteristics that any computer network should possess to function effectively.

💡Fault Tolerance

Fault tolerance is the ability of a system to continue operating in the event of a component failure. It ensures that services are not disrupted, which is critical for maintaining network reliability. The script uses the analogy of finding an alternative route home when the usual path is blocked to illustrate how a computer network should automatically reroute data in case of failure.

💡Scalability

Scalability is the capacity of a network to expand and accommodate growth, such as an increase in the number of connected devices or data traffic, without a decline in performance. The script exemplifies this with the growth of the Internet, which constantly integrates new devices while maintaining performance, highlighting the importance of scalability in network design.

💡Quality of Service (QoS)

Quality of Service is the ability to manage network resources to prioritize different types of data traffic, reducing data loss and latency. It is crucial for real-time applications like VoIP, where delays can severely impact communication quality. The script explains QoS by describing how a router might prioritize voice traffic over email during peak usage.

💡Security

Security in computer networks involves protecting data from unauthorized access, misuse, and forgery. It also encompasses ensuring confidentiality, integrity, and availability of information. The script discusses the importance of network security by illustrating the risks of data interception and the need to safeguard sensitive information during transmission.

💡VoIP (Voice-over IP)

VoIP stands for Voice-over Internet Protocol and is a technology that allows voice communication over the internet rather than traditional telephone lines. It is used in the script to demonstrate the prioritization of real-time data in QoS, as voice data requires immediate transmission to avoid disruptions in conversation.

💡Router

A router is a networking device that forwards data packets between computer networks, creating an overlay network. In the context of the script, routers play a critical role in routing data and implementing QoS by prioritizing certain types of traffic, as well as in fault tolerance by rerouting data in case of link failures.

💡Data Traffic

Data traffic refers to the transfer of data packets across a network. The script discusses how QoS manages data traffic by setting priorities, which is essential for efficient network operation, especially when multiple types of data are being transmitted simultaneously.

💡Confidentiality

Confidentiality in the context of computer networks is the protection of sensitive information from unauthorized access or disclosure. The script emphasizes the importance of confidentiality by explaining how encryption can ensure that only the intended sender and receiver can understand the transmitted data.

💡Integrity

Integrity in computer networks ensures that data remains unaltered during transmission. The script explains that network security must protect against modifications to data, guaranteeing that the receiver gets the exact information sent by the sender without any tampering.

💡Availability

Availability in network security refers to ensuring that network resources are accessible and usable when required. The script mentions the responsibility of a network to prevent unauthorized access that could lead to resource unavailability, such as defacement of web servers.

Highlights

Introduction to the basic characteristics of computer networks.

Outcomes of the session include understanding fault tolerance, scalability, Quality of Service (QoS), and security in networks.

Definition of fault tolerance as the ability of a network to continue working despite failures without loss of service.

An analogy of finding an alternative route home to explain fault tolerance.

Example of fault tolerance with a computer and web server communicating through various network devices.

Explanation of how a network redirects traffic in case of a failure to maintain communication.

Introduction to scalability as the network's ability to grow and maintain performance.

Use of the Internet as an example of a scalable network accommodating new devices.

Illustration of network scalability with the addition of 100 computers to a network.

Introduction to Quality of Service (QoS) as the ability to manage data traffic and reduce data loss and delays.

Explanation of QoS in prioritizing real-time communication over non-real-time data transfer.

Example of QoS with voice-over IP (VoIP) phone and email data being sent simultaneously.

Importance of prioritizing real-time communication due to the intolerance of delays.

Introduction to network security as the ability to prevent unauthorized access, misuse, and forgery.

Explanation of security's role in providing confidentiality, integrity, and availability of data.

Example scenario of sending confidential information and the potential risks without security measures.

Emphasis on the network's responsibility to secure data against attackers and ensure data integrity and availability.

Summary of the basic characteristics of computer networks: fault tolerance, scalability, QoS, and security.

Conclusion and anticipation of further discussion in upcoming lectures.

Transcripts

Hello everyone, welcome back to the computer networks course.

Today we shall see the basic characteristics of computer network.

Before we step in to the basic characteristics,

we shall set some outcomes of this session.

Upon the completion of this session, we will be able to understand

the need for fault tolerant networks and scalable networks.

We shall understand what is Quality of Service (QoS)

and we shall also understand

why do we need security in computer networks.

There are four basic characteristics any computer network should possess.

Fault tolerance

Scalability

Quality of Service (QoS)

and Security.

If we say there is a computer network

and that computer network should be fault tolerant,

it should be scalable, it should provide quality of service,

and it should also provide security.

We shall see each of these in a detailed manner.

Firstly, Fault tolerance.

Fault tolerance is the ability of the computer network

to continue working despite failures

and it should ensure there is no loss of service.

For example, if we have a computer network

and if there is a problem inside the computer network

but still the computer network should work even after failures.

And thereby there is no loss of service.

Before we go on to this example part,

you just visualize this scenario.

Imagine you are going home back from your college,

you know very well about the best route to reach your home.

And you prefer taking this regular best route.

Unfortunately, there is a blockage and you cannot take this route further.

What will you do now?

Will you go to your college back?

Or you will find the next available route to reach your home?

I guess, we all will find next available route

and we will take that route to reach home.

This is what we call as Fault Tolerance.

We shall see an example for fault tolerance now.

Let us assume that these two entities are communicating with each other.

This computer and this web server

through switch, this wireless router, this link, this router 1,

router 3, router 5, switch and web server.

Unfortunately, there is a failure

maybe either in the link or this router has gone down.

So this router instead of forwarding the data to this way,

it forwards the data to router 2.

So that, this communication between this computer and this web server

is not affected because of this failure.

This is what exactly is Fault Tolerance.

I hope now you understood why do we need fault tolerant network.

Because we need to work despite failures

and we need to ensure there is no loss of service.

This is what exactly is Fault Tolerance.

Now we shall see, the second basic characteristics: Scalability.

It is the ability to grow based on the needs.

And have good performance even after growth.

For example, if there are ten computers in a network,

and if again ten computers are added to the network,

this network should work as like the same

even after adding these ten computers.

We shall see an example for the scalable network.

The best example for a scalable network is the Internet.

Even this moment, many new devices are connecting

to internet and communicating to each other.

Internet handles this very perfectly and always gives scope for the newcomers.

This is what we exactly call as scalability.

In this example, assume 100 computers are connected to router 3

and we expect our computer network to work

as like the same even after adding these 100 devices.

This is what we call as scalability.

And this is the ability to grow based on the needs

and have good performance even after the growth of the network.

So far we have seen fault tolerance and scalability.

Now we shall see the third basic characteristic

of computer network, the Quality of Service.

It is the ability to set priorities

and manage data traffic to reduce data loss and delays.

For example, if a router receives two packet at a time

or two data at a time, and this router should know

to which data it should process first.

This is what we call as set priorities.

I shall explain about this quality of service in a detailed manner with an example.

Have you noticed something is new in this picture?

which was not there in our previous lecture?

It is the voice-over IP phone VoIP stands for voice-over IP phone.

And this phone is different from our traditional land-line phone.

This voice-over IP phone sends the voice data through the internet

whereas our traditional land-line phone sends the voice data

through the dedicated telephone network.

So this voice-over IP phone is like our whatsapp call.

In whatsapp call, our voice data is sent to the destination

through the internet, but not through the telephone network.

You may be wondering why I have brought in this voice over IP phone.

I shall explain you why I have brought in this voice-over IP phone for a reason.

Let's assume, this guy is sending some e-mail data

to an e-mail server through router 1.

At the same time, there are two guys

who are talking over voice-over IP phone through internet.

The situation is two guys are sending data at the same time

where this router 1 is experiencing both the traffic at the same time.

One is the e-mail traffic another one is the voice traffic

that is the real time communication.

Now the question is, to which data this router 1 will give priority?

Whether to the real time communication or to the e-mail data?

Actually, router 1 will process voice-over IP phone's data.

Why because, it is a real time communication.

In real time communication, delays are not accepted

whereas delays are not a problem in e-mail communication.

A delay of one second in an e-mail communication

is not going to hurt the communication.

Whereas a delay of one second in a real time communication matters a lot.

And that is why this router gives the priority to

real time communication than normal communication.

When router experiences two different kinds of data at the same time,

this router should be able know to which data it should give priority.

This is what we call as quality of service (QoS).

The main aspect of this quality of service is that,

it handles loss also it handles the delay.

Now we shall see the final characteristics of computer network,

that is the Security.

It is the ability to prevent unauthorized access, misuse or forgery.

Not only prevention, network should also provide

confidentiality, integrity and availability.

To understand why do we need security, we shall visit this example.

Suppose, someone from this computer is sending

some confidential information to amazon.com.

Once the data leaves our computer, it is not in our hands.

Internet has good guys as well as bad guys

whom we call as attackers.

Please note, attackers are bad guys.

Assume our confidential information is flowing through router 3,

and what if an attacker steals this information from router 3?

They get access to our computer,

they can misuse or they can also involve in forgery.

So it becomes an important task

for a computer network to provide confidentiality.

That is, the data which is not sent just like that as what we had sent.

It means, if it is a confidential data,

this data is converted to a different form,

and that form is understandable only by the sender and the receiver.

At the same time, there should not be any modification to the data sent,

that is this network should provide integrity.

Whatever the sender is sending that only the receiver should receive.

So this property is called as integrity.

Attacker always try to deface this web servers

so that this resource becomes unavailable for access.

So it becomes the ultimate responsibility

of a computer network to provide security.

Because, network should prevent

unauthorized access, misuse and forgery

and it should also provide

confidentiality, integrity and availability.

I hope now you are clear with all the basic characteristics of a computer network.

A fault tolerant network, a scalable network,

the quality of service and security.

Thank you for watching.

We shall meet again in the upcoming lectures.