Hi, Daddy.
This might have that here and there.
This first lecture, I have to do an introduction about multicast.
So multicast is to provide a streaming for many users or many machines.
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
about this topic.
That's why I have decided to make this course.
So to help you to understand everything about multicast.
So before we start speaking about multicast and detection, do the labs, we have to have the introduction
to understand what is multicast and what are the different types of traffic we have on the IP version
four and what are the components of multicast?
And then after that, we can take each of these components and we can build the lab to show you how
you can do streaming using multicast.
So let's start directly now with the explanation about the introduction of multicast.
So as you know, we have three types of traffic on the IP version four.
On IP version six, you have something a bit different.
For example, on IP, very often we will see in a moment we do have the broadcast one on IP, version
six broadcast is not that anymore, but there is any cost.
But in this course we are going to focus on the IP version four and not on IP version six.
So as I said, we have three types of traffic.
We have the unicast, we have the broadcast and we have the multicast.
So say that you have a media server that is stable or want to stream some videos and that issues are
over here on this computer, want to receive this streaming video.
Then if you use unicast, then this means that this server will send it to the switch or to the network
and then it will go directly to this computer.
Those two computers over here will not receive the streaming video, so that's what the unicast is.
So it is 1 to 1 how this works.
This server over here, he showed that I want to send this traffic to this destination, Mac either.
So he uses the destination of this computer and then the switch has what we call it, the Mac other
stable, and then he can forward the traffic to this computer.
So it is 1 to 1, but say that you have another computer.
Want also to receive the streaming video that this server would have to send two streaming videos,
one for the first PC and one for the second PC.
That means if you have an SD, for example, high definition video which requires something like six
megabits, so now the server is sending 12 megabits of boundaries on the network, which makes more
load on the shoba itself on these resources.
And also it will take capacity from the network.
So again, unicast is 1 to 1, from one source to one this dimension.
Let's see now the other type of traffic that we have on our network design type that we have as broadcast.
Broadcast means one to all.
That means that this server was sent only one stream and then it comes to the switch and then the switch
will send it to all export, but not from the ports from which it came from.
So it will not send it out from the spot.
So this will not work like this.
So send it to all those computers, which is okay.
But again, say that this one one the streaming video and this one doesn't want that this one doesn't
want that, even though that picture basically Doudou does not want it, there was to receive it because
that's for broadcast wan to all.
And also broadcast is not something very nice under the network because once you have broadcast then
normally the network will slow down.
So think of broadcast something like the ACP and the AAP.
The ACP cannot use the broadcast.
So for example, when you you know what this PR there should be is to provide IP address something that
means gateway and so forth to a machine.
So once a machine is up and it wants to desire information to send the broadcast searching for a there
should be server and leadership whichever one it here this request it will provide this information.
So this is what broadcast is.
Of course, if you look at it, this server over here is streaming only one stream.
So that means only one stream would go for everybody, which is a little bit better than here, because
this one is every machine will get one stream.
So as for the bandwidth as it is and also the log on the server, it is better.
But again, that's some broadcast.
It's not very efficient.
So what is the best solution?
That is the multicast.
I'm going to speak to you about it in a moment.
Now, the third type of traffic we have is multicast.
Let me just remove my video so you can see what I'm standing here.
So multicast means that you have one server streaming the video and it goes to the switch and that only
the computers which want it will receive it.
So this one does not want it.
So this one will not get the stream, this one and this one will get it.
That's why I would call it multicast.
Is one too many.
So it's not one to all like a broadcast.
It's not 1 to 1.
Like unique assets is one too many.
So it goes to the switch and the switch will send it to the computer.
So then you need only one stream which takes less load on the server.
And also, as for traffic, if you are using HD again, you'll have to use only six megabits.
So only one time you send six megabits and then the switch will send those stream to the receiver machines.
In this case, which I'd pursue on ABC, to be sure she would not get anything.
So my multicast is the best solution.
And we always say that the multicast, when you want to use some streaming video on your LAN, always
go to multicast because it's the most efficient solution.
Now, a lot of people, things like YouTube or some other streaming videos like Netflix, for example,
they use Matic, but in fact they do not because those are those application.
They use unicast.
So they use because actually every machine is asking for a video so it doesn't work like multicast.
Multicast, why do you see it is mostly inside the ISP's where they are streaming some type of videos
and then they allow their subscribers to be able to watch those videos.
So now we understand about the unicast broadcast multicast.
Let's see now a little bit more and details about every one of those.
Why don't we put it in a real scenario?
So now I'm putting the unicast and astronaut are say that we have here there is a network over here
and this is connected to a router and then we have 30 megabits of capacity between those two Rotterdam.
You have another network here say that those computers over here, they want to receive the streaming
which is coming from the server and we are using unicast.
We said that they request something like six megabits per second.
Then this sugar was sent for this one, six megabit was sent for just one six megabit.
Then those two also want the the streaming video that it will send also to stream six megabit and six
megabits.
So in total on the first network, we have six plus six because we have two computers.
So it was sent 12 megabits over here.
And on this one, because we have a short time ago, as you can see, to also send 12 megabits per second.
All right.
Now, in this case, it's not a problem because you have 30 megabits here.
So if that takes 12 megabits out of the church megabits, then you have left 80 megabits for Internet
of whatever to connect to the shared offices to each other.
So that's fine.
You can still use the 80 megabit, but what if over here on this network you have ten receivers and
not two?
So you have to think of ten times six, that 60 megabit then you have here certainly megabits of capacity
on this one.
So this is not enough to be able to stream the video to all the ten machines that are on this network.
You got the idea.
So because unicast, as I said, it wasn't one stream per connection, per request.
So that means if you have ten machines, then it has to send then unicast.
Ten times six.
That's 60 megabits.
So that's not possible.
So now we understand the problem of the unicast.
Let's see now the problem of the broadcast.
So the other example that I wanted to show you here is to broadcast say that we have also this streaming
video and we have the same scenario.
We have two offices here connected to we are 30 megabit of speeds here, the two routers.
And we have on this network two matches on this network, two machines on this network, the first network,
we have one that want the stream.
The second one doesn't want the stream.
And on the same network we have two that want this streaming video to be received.
So what's going to happen in the broadcast?
We say there's one to all.
So this server will just send it to the switch and the switch, send it to all export.
Unless the point that it has received the streaming from the trains, it will send it to here to send
it to here.
It was sent it to here.
What's going to happen?
This one will receive the stream.
That's fine.
He can receive the video.
But this one is we said he doesn't want this.
He said here, I don't want this.
So.
But he still received the broadcast.
All right.
That's one of the problems of the broadcast.
Now, when it comes to the router, the problem is, as we said, to send it to here to be able to go
to those two computers here.
Right.
But as we know from the network basics that the broadcast is stopped by the Layer Srey devices, which
is a router.
So once they're out of CE, it's a broadcast, it will say, hey, you are broadcast, stop.
You cannot go further.
So what's going to happen that those two machines over here will not receive the streaming?
And you can see I'm not receiving the streaming.
So that is another problem that my encounter on the broadcast is that in case you are sending the streaming
to another network where you have a necessary device in between separating the broadcast domains, then
in this case, there will not get the streaming.
So what is the solution?
Let's see now the multicast if it can solve this problem.
So now we have understood the scenario of the unicast broadcast and we have seen that there are some
problems over there that let's see now what will happen with the unicast.
So unicast discover we said we send it to groups of users.
So here this computer wanted, this computer wanted, this computer is on one network and this computer
is another network.
So it will send it to the switch to switch send directly to here we see later what is the mechanism
that they know that this computer want the streaming video, but it will send it.
And believe it or not, this shows that only one stream of six megabit percent and only one stream it
goes through here, then it can go to the router.
The router was send it or this rather.
So here it's not like the broadcast.
It will stop the traffic.
It will send it to here.
We'll see.
Also, what type of protocol is used between the restaurateurs to send the traffic that come to the
switch.
The switch does not send it to here because he knows that this computer doesn't want that.
Then it will send it to this computer, which he wanted.
So then in this case, what we see, we have six megabits, so only one streaming.
We have only the computers that niche, the streaming of viewership that have received it and it has
bypassed the others to be able to receive to the other network.
So that is the solution.
Multicast is the solution when we want to use streaming videos.
Now we understand about the scenario unicast multicast on broadcast.
Let's now speak a little bit about what are the components that we use on multicast.
Basically what we need to know, we need to know about the protocols that are being used on multicast.
The first thing that I want to explain to you about it is that multicast use the Class D range.
We know on IP version four, we have a class we can see.
That's what we normally use inside our network.
But multicast use the class D which start from 2 to 4 .0.00 on to 239.255.245.255.
So those are the other issues of the multicast, but for the destination, so the multicast was sent
to a destination having any of this range from here to here and.
And it is sent.
We call it the to a group of multicast.
Then in this case, the source.
It's always the IP of the server, but the it always send it to the destination, which is the a class
DB.
Okay.
So remember, it cannot be a source.
It has to be destination.
So now say that we have this scenario, this server, send it to the router.
Now the rocker.
He needs to know.
Where should shall he send the multicast?
Because he shylock.
I received the streamer.
What shall I do with that?
Shall I send it to one of these machines?
Or to all of them?
Or to two of them?
Or shall I drop it?
So what shall I do with this traffic now?
What will happen in the background is that this computer.
Which has the software to be able to run the streaming video.
It wasn't something we call it the ICMP, which is the Internet Group Management Protocol.
So it was say to the rather hey, rather, if you receive the streaming video from the streaming server,
I want that.
Those will not say anything.
So I will not use agent P to tell the rather because they don't want it.
But this one will say I wanted.
That's why once this comes to the router, the streaming video than the router knows that this computer
wanted then he was southern Asia IP is a very important protocol that is used to be able for the rather
to know why should he send the traffic for the multicast.
Now we understand about the deal with the usage of the IP.
Let's put here a switch to see if we have a switch in between.
What's going to happen?
So we said that any time a computer that want to receive the streaming video, he was send Agent B to
drop it, telling him that I want to receive this streaming from you.
Right.
That's what we have seen in the previous slide.
Now, if we have a switch in between, what's going to happen?
So the server was sent to the router.
There are two knows that this computer want the multicast and he will send it down to the switch.
Now the switch he doesn't understand because remember the switch looks to the other stable Mac address
stable.
So he will see that that.
Yeah, I don't have a destination of a computer to send the information to him.
So how can the switch know that the this PC wants to receive the traffic for the streaming?
So what happens is that on the background, once this computer sent information to the router, which
is the ICMP, asking him that if you receive to me, I want it.
So on the background, because this traffic is anyway going via the switch, right.
To be able to arrive to the rather than the switch has something we call it the ICMP snooping.
ICMP snooping.
That means he will listen to the agent B once it comes from the computer to the router and you say,
Oh no, I know that this computer want to receive this streaming.
So then once the streaming goes to the radar and the radio to send it to the switch, then the switch
knows that the yes to only send it to this computer because he has listened to the IP that is happening
in the background.
So that's that the idea of the IGP stop you all what you see now about IGP Asia IP snooping and now
in an upcoming slide we are going to speak about the PIN, all of those who are going to make laps for
that to show it to you in a real scenario how this works.
So remember once the computer want to get any is streaming video he was sent IGP to the router.
That's why they're out of knows how to send the down to the computer in case there is a switching between.
Once this communication of IGP is happening between the PC and the rather, the switch will have something
we call it agent snooping.
Then he will listen that this computer want the streaming, then wanted to receive the streaming video
from the rather than he can send it to the PC.
Now we understand about the champion IGP snooping.
Let's see if we have now two or more routers, how this would work.
All right.
So say now that we have a streaming video and those wishes here, there is one who want to have the
streaming video.
So it it is a stream ashover over here doing the streaming.
Once this sent to the router, one we have here without the one to take to decision whether from rather
to or from rather.
Sorry.
So how can the router knows which is rather wan which has to send the multicast traffic promoter to
troubleshoot.
Remember we said that the multicast use the class D.
So that means that once if we go back to the routing protocol like grep or OSPF or whatever, all those
rather for the what they do, they just open the routing table and they look what is the destination
and they send it to the closest destination.
Right, which is the best route.
That's what all those routing protocol does.
But for our case on multicast, there is no destination and the turn of like and that's what that it
needs to be.
There is a multicast group address which is two, three, nine, for example, or 0.0.1.
So over here, the whole concept that we know about the router protocol that it will send it to the
closest destination based on the routing table is not that.
So in this case, we need to have some other mechanism.
So the router one knows how to send the traffic of the multicast.
What rather one does is use what we call it the PIM premise protocol, independent multicast.
With this protocol, then rather one will know if he has to send the traffic VR archive.
Two or VR router three.
Now there are some other protocols or multicast routing protocols, we call them, that are being used
in some other vendors because migrating they only use them.
But then some other vendors you may see something like DV, MRP, which is this inverter multicast routing
protocol and or Hpf, which is multicast open shortest path first.
So you have those two routing protocols that you can see them and some other vendors, but for migrating
we only see Ben.
So Pim is the only multicast driving protocol that is being used to be able to forward the traffic from
a router to another.
And that's something again we are going to see it when we do labs about them in this course.
So this is all what I wanted to show you in this first lecture is all about introduction to understand
about what the type of traffic should we have to understand about the component of multicast.
And with this explanation, I think now you are on the right track to know about multicast.
So I hope that this lecture was informative for you, and I wish you in the upcoming lecture.