Computer Networks - Basic Characteristics-02

Computer Networks: Basic Characteristics of Computer Networks

Topics discussed:

1) Fault tolerance in Computer Networks.

2) Scalability in Computer Networks.

3) Quality of Service (QoS) in Computer Networks.

4) Security in Computer Networks.

Transcript

hello everyone welcome back to the

computer networks course and today we

shall see the basic characteristics of

computer network before we step into 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 and we shall also understand why

do we need security in computer networks

there are 4 basic characteristics any

computer network should possess fault

tolerance scalability quality of service

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 the 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

the 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 one 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 through this way it

forwards the data to router two so that

this communication between this computer

and this webserver is not affected

because of this failure this is what

exactly 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

fault tolerance now we shall see the

second basic characteristic scalability

it is the ability to grow based on the

needs and have good performance even

after growth for example if there are 10

computers in a network and if again 10

computers are added to the network this

network should work as like the same

even after adding these 10 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's internet handles this very

perfectly and always gives hope for the

newcomers this is what we exactly called

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 hundred devices this is what we

call a 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 a 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 form

vivo IP stands for voice over IP phone

and this phone is different from our

traditional landline phone this voice

over IP phone since the voice data

through the internet whereas our

traditional landline phone since 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

email data to an email server through

router one 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

one is experiencing both the traffic at

the same time one is the email 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 email

data actually route of 1 will process

voice over IP phones data why because it

is a real-time communication in

real-time communication delays are not

accepted whereas delays are not a

problem in email communication a delay

of one second in an email 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

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 to know to which data should you

priority this is what we call as quality

of service the main aspect of this

quality of services that it handles law

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 and 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 if that form can be

understandable only by the sender and

the receiver at the same time there is

no modification of data sent should be

there that is this network should

provide integrity whatever the sender is

sending that only the receiver should

receive so this property we call as

integrity attacker always tried 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

[Applause]

[Music]