1

00:00:00,060 --> 00:00:07,170

Well, in the previous two lectures, we have seen what a network interface card is and the other devices



2

00:00:07,170 --> 00:00:08,890

which you are going to learn in this section.



3

00:00:09,420 --> 00:00:16,440

Now it's time to move on to the next device that is the hub you have heard many times from me throughout



4

00:00:16,440 --> 00:00:20,700

this lecture and in this lecture, I will tell you more about a hub.



5

00:00:21,720 --> 00:00:29,280

So as you learned earlier, a hub is a device that connects all segments of the network together in



6

00:00:29,280 --> 00:00:30,450

a star topology.



7

00:00:30,990 --> 00:00:35,410

So as the hub has no intelligence, it is a layer one device.



8

00:00:35,760 --> 00:00:37,390

So basically, what is a hub?



9

00:00:37,410 --> 00:00:41,380

It's a device which is used to connect to our network segments together.



10

00:00:41,880 --> 00:00:43,400

So it access center point.



11

00:00:43,710 --> 00:00:49,380

We have seen in the star topology that the central device which connects all the hosts is a hub.



12

00:00:49,800 --> 00:00:53,610

Now in that case, the hub was connected to all of the computers.



13

00:00:54,360 --> 00:00:59,260

Similarly, different network segments can be used to connect together through a hub.



14

00:00:59,820 --> 00:01:01,380

The hub has no intelligence.



15

00:01:01,680 --> 00:01:02,570

What does it mean?



16

00:01:02,610 --> 00:01:04,710

What is a no intelligence device?



17

00:01:05,460 --> 00:01:12,750

Basically, no intelligence device is a device which does not recognize any frames or data packets that



18

00:01:12,750 --> 00:01:15,030

are sent through it, for example.



19

00:01:15,300 --> 00:01:21,200

Or consider a network of having five pieces, let's say A, B, C, D and E.



20

00:01:22,170 --> 00:01:24,170

Now you need to visualize what I'm telling you.



21

00:01:24,600 --> 00:01:32,460

So suppose if ABC wants to send data packet to frame E, so when the data packet passes through the



22

00:01:32,460 --> 00:01:37,170

hub, the hub does not recognize that this packet is only intended for free.



23

00:01:37,190 --> 00:01:44,450

E I'm sorry for host E it randomly sends the packets to all the hosts and that is why it is a normal



24

00:01:44,490 --> 00:01:45,630

intelligence device.



25

00:01:46,020 --> 00:01:52,590

Now each device in the network connected directly to the hub through a single cable and it is used to



26

00:01:52,590 --> 00:01:55,830

connect multiple devices without segmenting the network.



27

00:01:56,520 --> 00:02:02,880

Any transmission received on one board will be sent out to all other ports in the hub, including the



28

00:02:02,880 --> 00:02:07,680

receiving power for the transmitting device, like I explained a couple of minutes ago.



29

00:02:09,060 --> 00:02:16,080

So basically, this means that if one station sends a broadcast to all others will receive it.



30

00:02:16,090 --> 00:02:21,990

Yet on the addressing, found in the frame is different and it is intended only for the recipient.



31

00:02:23,340 --> 00:02:29,180

Now, this arrangement simulates the physical books that the SEALs may see the standard was based upon.



32

00:02:29,850 --> 00:02:33,280

Don't worry about these terminologies, CDMA and CD.



33

00:02:33,320 --> 00:02:36,210

I'm going to explain all these in the upcoming lectures.



34

00:02:36,810 --> 00:02:39,030

So again, do not skip any lecture.



35

00:02:40,440 --> 00:02:49,440

However, if there are there were 20 users on one PC and if suppose one computer wants to personally



36

00:02:49,440 --> 00:02:53,980

chat with another PC, the entire message gets delivered to all the hosts.



37

00:02:54,480 --> 00:02:57,240

This results in the wastage of resources.



38

00:02:57,240 --> 00:03:03,000

We still have electricity and that is why help is not used for today's resources, because in today's



39

00:03:03,000 --> 00:03:09,690

network there are millions of PCs connected to each other and you don't want the message to be delivered



40

00:03:09,690 --> 00:03:12,640

to all of the remaining posts on the network.



41

00:03:13,170 --> 00:03:17,760

So what do you need to remember about how is that?



42

00:03:18,330 --> 00:03:24,120

Hub is a new intelligence device and it is just used to connect all the network segments together.



43

00:03:25,020 --> 00:03:31,420

A broadcast sent out by any device on the hub will be propagated to all the devices connected to it.



44

00:03:31,440 --> 00:03:36,120

You have to remember this because this might be asked in a question where you have to tell the difference



45

00:03:36,120 --> 00:03:38,420

between a hub and a bridge.



46

00:03:38,970 --> 00:03:42,240

So in the next lecture, we'll talk more about bridge.