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Hi, Daddy.

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This might have that here and there.

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This first lecture, I have to do an introduction about multicast.

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So multicast is to provide a streaming for many users or many machines.

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This topic is not very clear for a lot of our students and on my codec also we don't find a lot of resources

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about this topic.

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That's why I have decided to make this course.

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So to help you to understand everything about multicast.

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So before we start speaking about multicast and detection, do the labs, we have to have the introduction

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to understand what is multicast and what are the different types of traffic we have on the IP version

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four and what are the components of multicast?

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And then after that, we can take each of these components and we can build the lab to show you how

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you can do streaming using multicast.

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So let's start directly now with the explanation about the introduction of multicast.

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So as you know, we have three types of traffic on the IP version four.

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On IP version six, you have something a bit different.

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For example, on IP, very often we will see in a moment we do have the broadcast one on IP, version

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six broadcast is not that anymore, but there is any cost.

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But in this course we are going to focus on the IP version four and not on IP version six.

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So as I said, we have three types of traffic.

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We have the unicast, we have the broadcast and we have the multicast.

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So say that you have a media server that is stable or want to stream some videos and that issues are

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over here on this computer, want to receive this streaming video.

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Then if you use unicast, then this means that this server will send it to the switch or to the network

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and then it will go directly to this computer.

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Those two computers over here will not receive the streaming video, so that's what the unicast is.

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So it is 1 to 1 how this works.

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This server over here, he showed that I want to send this traffic to this destination, Mac either.

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So he uses the destination of this computer and then the switch has what we call it, the Mac other

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stable, and then he can forward the traffic to this computer.

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So it is 1 to 1, but say that you have another computer.

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Want also to receive the streaming video that this server would have to send two streaming videos,

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one for the first PC and one for the second PC.

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That means if you have an SD, for example, high definition video which requires something like six

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megabits, so now the server is sending 12 megabits of boundaries on the network, which makes more

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load on the shoba itself on these resources.

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And also it will take capacity from the network.

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So again, unicast is 1 to 1, from one source to one this dimension.

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Let's see now the other type of traffic that we have on our network design type that we have as broadcast.

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Broadcast means one to all.

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That means that this server was sent only one stream and then it comes to the switch and then the switch

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will send it to all export, but not from the ports from which it came from.

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So it will not send it out from the spot.

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So this will not work like this.

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So send it to all those computers, which is okay.

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But again, say that this one one the streaming video and this one doesn't want that this one doesn't

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want that, even though that picture basically Doudou does not want it, there was to receive it because

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that's for broadcast wan to all.

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And also broadcast is not something very nice under the network because once you have broadcast then

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normally the network will slow down.

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So think of broadcast something like the ACP and the AAP.

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The ACP cannot use the broadcast.

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So for example, when you you know what this PR there should be is to provide IP address something that

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means gateway and so forth to a machine.

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So once a machine is up and it wants to desire information to send the broadcast searching for a there

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should be server and leadership whichever one it here this request it will provide this information.

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So this is what broadcast is.

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Of course, if you look at it, this server over here is streaming only one stream.

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So that means only one stream would go for everybody, which is a little bit better than here, because

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this one is every machine will get one stream.

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So as for the bandwidth as it is and also the log on the server, it is better.

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But again, that's some broadcast.

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It's not very efficient.

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So what is the best solution?

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That is the multicast.

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I'm going to speak to you about it in a moment.

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Now, the third type of traffic we have is multicast.

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Let me just remove my video so you can see what I'm standing here.

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So multicast means that you have one server streaming the video and it goes to the switch and that only

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the computers which want it will receive it.

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So this one does not want it.

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So this one will not get the stream, this one and this one will get it.

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That's why I would call it multicast.

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Is one too many.

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So it's not one to all like a broadcast.

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It's not 1 to 1.

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Like unique assets is one too many.

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So it goes to the switch and the switch will send it to the computer.

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So then you need only one stream which takes less load on the server.

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And also, as for traffic, if you are using HD again, you'll have to use only six megabits.

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So only one time you send six megabits and then the switch will send those stream to the receiver machines.

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In this case, which I'd pursue on ABC, to be sure she would not get anything.

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So my multicast is the best solution.

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And we always say that the multicast, when you want to use some streaming video on your LAN, always

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go to multicast because it's the most efficient solution.

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Now, a lot of people, things like YouTube or some other streaming videos like Netflix, for example,

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they use Matic, but in fact they do not because those are those application.

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They use unicast.

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So they use because actually every machine is asking for a video so it doesn't work like multicast.

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Multicast, why do you see it is mostly inside the ISP's where they are streaming some type of videos

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and then they allow their subscribers to be able to watch those videos.

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So now we understand about the unicast broadcast multicast.

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Let's see now a little bit more and details about every one of those.

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Why don't we put it in a real scenario?

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So now I'm putting the unicast and astronaut are say that we have here there is a network over here

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and this is connected to a router and then we have 30 megabits of capacity between those two Rotterdam.

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You have another network here say that those computers over here, they want to receive the streaming

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which is coming from the server and we are using unicast.

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We said that they request something like six megabits per second.

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Then this sugar was sent for this one, six megabit was sent for just one six megabit.

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Then those two also want the the streaming video that it will send also to stream six megabit and six

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megabits.

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So in total on the first network, we have six plus six because we have two computers.

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So it was sent 12 megabits over here.

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And on this one, because we have a short time ago, as you can see, to also send 12 megabits per second.

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All right.

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Now, in this case, it's not a problem because you have 30 megabits here.

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So if that takes 12 megabits out of the church megabits, then you have left 80 megabits for Internet

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of whatever to connect to the shared offices to each other.

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So that's fine.

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You can still use the 80 megabit, but what if over here on this network you have ten receivers and

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not two?

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So you have to think of ten times six, that 60 megabit then you have here certainly megabits of capacity

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on this one.

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So this is not enough to be able to stream the video to all the ten machines that are on this network.

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You got the idea.

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So because unicast, as I said, it wasn't one stream per connection, per request.

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So that means if you have ten machines, then it has to send then unicast.

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Ten times six.

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That's 60 megabits.

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So that's not possible.

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So now we understand the problem of the unicast.

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Let's see now the problem of the broadcast.

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So the other example that I wanted to show you here is to broadcast say that we have also this streaming

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video and we have the same scenario.

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We have two offices here connected to we are 30 megabit of speeds here, the two routers.

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And we have on this network two matches on this network, two machines on this network, the first network,

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we have one that want the stream.

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The second one doesn't want the stream.

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And on the same network we have two that want this streaming video to be received.

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So what's going to happen in the broadcast?

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We say there's one to all.

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So this server will just send it to the switch and the switch, send it to all export.

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Unless the point that it has received the streaming from the trains, it will send it to here to send

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it to here.

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It was sent it to here.

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What's going to happen?

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This one will receive the stream.

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That's fine.

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He can receive the video.

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But this one is we said he doesn't want this.

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He said here, I don't want this.

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So.

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But he still received the broadcast.

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All right.

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That's one of the problems of the broadcast.

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Now, when it comes to the router, the problem is, as we said, to send it to here to be able to go

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to those two computers here.

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Right.

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But as we know from the network basics that the broadcast is stopped by the Layer Srey devices, which

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is a router.

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So once they're out of CE, it's a broadcast, it will say, hey, you are broadcast, stop.

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You cannot go further.

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So what's going to happen that those two machines over here will not receive the streaming?

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And you can see I'm not receiving the streaming.

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So that is another problem that my encounter on the broadcast is that in case you are sending the streaming

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to another network where you have a necessary device in between separating the broadcast domains, then

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in this case, there will not get the streaming.

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So what is the solution?

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Let's see now the multicast if it can solve this problem.

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So now we have understood the scenario of the unicast broadcast and we have seen that there are some

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problems over there that let's see now what will happen with the unicast.

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So unicast discover we said we send it to groups of users.

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So here this computer wanted, this computer wanted, this computer is on one network and this computer

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is another network.

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So it will send it to the switch to switch send directly to here we see later what is the mechanism

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that they know that this computer want the streaming video, but it will send it.

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And believe it or not, this shows that only one stream of six megabit percent and only one stream it

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goes through here, then it can go to the router.

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The router was send it or this rather.

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So here it's not like the broadcast.

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It will stop the traffic.

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It will send it to here.

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We'll see.

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Also, what type of protocol is used between the restaurateurs to send the traffic that come to the

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switch.

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The switch does not send it to here because he knows that this computer doesn't want that.

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Then it will send it to this computer, which he wanted.

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So then in this case, what we see, we have six megabits, so only one streaming.

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We have only the computers that niche, the streaming of viewership that have received it and it has

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bypassed the others to be able to receive to the other network.

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So that is the solution.

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Multicast is the solution when we want to use streaming videos.

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Now we understand about the scenario unicast multicast on broadcast.

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Let's now speak a little bit about what are the components that we use on multicast.

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Basically what we need to know, we need to know about the protocols that are being used on multicast.

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The first thing that I want to explain to you about it is that multicast use the Class D range.

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We know on IP version four, we have a class we can see.

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That's what we normally use inside our network.

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But multicast use the class D which start from 2 to 4 .0.00 on to 239.255.245.255.

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So those are the other issues of the multicast, but for the destination, so the multicast was sent

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to a destination having any of this range from here to here and.

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And it is sent.

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We call it the to a group of multicast.

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Then in this case, the source.

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It's always the IP of the server, but the it always send it to the destination, which is the a class

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DB.

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Okay.

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So remember, it cannot be a source.

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It has to be destination.

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So now say that we have this scenario, this server, send it to the router.

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Now the rocker.

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He needs to know.

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Where should shall he send the multicast?

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Because he shylock.

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I received the streamer.

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What shall I do with that?

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Shall I send it to one of these machines?

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Or to all of them?

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Or to two of them?

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Or shall I drop it?

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So what shall I do with this traffic now?

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What will happen in the background is that this computer.

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Which has the software to be able to run the streaming video.

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It wasn't something we call it the ICMP, which is the Internet Group Management Protocol.

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So it was say to the rather hey, rather, if you receive the streaming video from the streaming server,

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I want that.

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Those will not say anything.

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So I will not use agent P to tell the rather because they don't want it.

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But this one will say I wanted.

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That's why once this comes to the router, the streaming video than the router knows that this computer

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wanted then he was southern Asia IP is a very important protocol that is used to be able for the rather

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to know why should he send the traffic for the multicast.

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Now we understand about the deal with the usage of the IP.

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Let's put here a switch to see if we have a switch in between.

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What's going to happen?

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So we said that any time a computer that want to receive the streaming video, he was send Agent B to

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drop it, telling him that I want to receive this streaming from you.

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Right.

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That's what we have seen in the previous slide.

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Now, if we have a switch in between, what's going to happen?

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So the server was sent to the router.

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There are two knows that this computer want the multicast and he will send it down to the switch.

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Now the switch he doesn't understand because remember the switch looks to the other stable Mac address

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stable.

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So he will see that that.

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Yeah, I don't have a destination of a computer to send the information to him.

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So how can the switch know that the this PC wants to receive the traffic for the streaming?

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So what happens is that on the background, once this computer sent information to the router, which

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is the ICMP, asking him that if you receive to me, I want it.

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So on the background, because this traffic is anyway going via the switch, right.

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To be able to arrive to the rather than the switch has something we call it the ICMP snooping.

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ICMP snooping.

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That means he will listen to the agent B once it comes from the computer to the router and you say,

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Oh no, I know that this computer want to receive this streaming.

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So then once the streaming goes to the radar and the radio to send it to the switch, then the switch

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knows that the yes to only send it to this computer because he has listened to the IP that is happening

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in the background.

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So that's that the idea of the IGP stop you all what you see now about IGP Asia IP snooping and now

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in an upcoming slide we are going to speak about the PIN, all of those who are going to make laps for

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that to show it to you in a real scenario how this works.

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So remember once the computer want to get any is streaming video he was sent IGP to the router.

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That's why they're out of knows how to send the down to the computer in case there is a switching between.

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Once this communication of IGP is happening between the PC and the rather, the switch will have something

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we call it agent snooping.

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Then he will listen that this computer want the streaming, then wanted to receive the streaming video

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from the rather than he can send it to the PC.

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Now we understand about the champion IGP snooping.

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Let's see if we have now two or more routers, how this would work.

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All right.

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So say now that we have a streaming video and those wishes here, there is one who want to have the

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streaming video.

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So it it is a stream ashover over here doing the streaming.

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Once this sent to the router, one we have here without the one to take to decision whether from rather

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to or from rather.

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Sorry.

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So how can the router knows which is rather wan which has to send the multicast traffic promoter to

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troubleshoot.

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Remember we said that the multicast use the class D.

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So that means that once if we go back to the routing protocol like grep or OSPF or whatever, all those

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rather for the what they do, they just open the routing table and they look what is the destination

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and they send it to the closest destination.

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Right, which is the best route.

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That's what all those routing protocol does.

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But for our case on multicast, there is no destination and the turn of like and that's what that it

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needs to be.

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There is a multicast group address which is two, three, nine, for example, or 0.0.1.

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So over here, the whole concept that we know about the router protocol that it will send it to the

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closest destination based on the routing table is not that.

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So in this case, we need to have some other mechanism.

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So the router one knows how to send the traffic of the multicast.

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What rather one does is use what we call it the PIM premise protocol, independent multicast.

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With this protocol, then rather one will know if he has to send the traffic VR archive.

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Two or VR router three.

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Now there are some other protocols or multicast routing protocols, we call them, that are being used

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in some other vendors because migrating they only use them.

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But then some other vendors you may see something like DV, MRP, which is this inverter multicast routing

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protocol and or Hpf, which is multicast open shortest path first.

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So you have those two routing protocols that you can see them and some other vendors, but for migrating

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we only see Ben.

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So Pim is the only multicast driving protocol that is being used to be able to forward the traffic from

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a router to another.

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And that's something again we are going to see it when we do labs about them in this course.

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So this is all what I wanted to show you in this first lecture is all about introduction to understand

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about what the type of traffic should we have to understand about the component of multicast.

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And with this explanation, I think now you are on the right track to know about multicast.

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So I hope that this lecture was informative for you, and I wish you in the upcoming lecture.