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I know that this might have that here again.

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So in this lecture I have to give explanation about Penn.

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So them is the protocol independent multicast, which is the we have to call it something like the multicast

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routing protocol.

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So set first that we forget a bit about BIM and we just think about the route protocol that we normally

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know.

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So say that you have this network and it also want to send traffic to one or two.

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I say to the two, which is this computer on the unit cached routing, what's going to happen that once

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this traffic comes to router two, router two will open his talking table, which is over here at Hiroshi?

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Do I have any entry to reach through one or two?

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I say the two, the two.

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Then he will look at me, say, Oh, I have one answer here saying that to go to one or two, I say

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the to the zero network, which is the network of one or two, I say go to the two, then I have to

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send everything out of my interface internet two because this is directly connected to me.

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Then Router two will know that he has to send the traffic like this.

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So that's something we know about routing in unicast.

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So that's what we are talking about unicast.

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So what is going to happen when we speak about the multicast?

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So we have this scenario, we have this video streaming and we have this computer which is the receiver.

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And we said that the on the multicast we always send to a group multicast group which is something like

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239.1.2.3.

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So this is the destination and this source is coming from the server which is one 7216 .1. 100.

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Now this traffic will come to the outcome.

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If we think about the unicast, the delta, what he has to do this is to look to his drafting table

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and he has to see if he knows about the destination, which is 239.12 to the stream.

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Then if we look on his routing table, that is his routing table.

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Look, he doesn't know anything about two, three nine.

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The one, the two, the street.

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He knows about one.

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So 216 12. 68i want to do a set of data point here too.

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So he knows those are from connected, that is from ICF, but he doesn't know anything about the multicast,

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which is 239.12 to the stream.

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So you can see you say I have no clue where to forward what the catastrophic two and what's going to

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happen if you did not configure something like BIM then the traffic will be discarded.

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That would be dropped completely and then this computer over here would never received the map, the

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catastrophic.

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So to avoid this, we need to have some mechanism and the mechanism that we need to use is spend that

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I'm going to explain to you in the upcoming slide.

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So then which is on my could take them as Spanish mode.

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So that's the mode that migrated to use because that is another mode called dense mode.

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That's something you can see on some other vendors like Cisco.

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But the micro thing, the only Pim that is used is the Pim s and so as I'm it's configured to make the

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counter Dorado is only for work to map the catastrophic one another rather request for that traffic.

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So that's something you have to keep in mind that the once you configure PIM in case the router received

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requests from other operators, you want them out there.

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Marcos then he was sending multicast.

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If he doesn't receive anything, then he doesn't show that they're multicast.

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While Pim de am which is on Cisco.

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The Dutch more than the multicast is always flooded once received.

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So once the multicast comes to the upstream interface, then it will always be flooded.

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However, at this moment there's not a variable on my dick, so the only option that we have is Pim,

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as I have said, which is in my opinion it's more scalable than than the.

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So my colleagues have done a very good job to just put them aside because in my opinion that business

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is better than the team.

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The now we have a question that may come to the mind, which is how can the routers or other authors

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know how to reach that dropper if they want the multicast offer?

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So that means the rafter, which is the upstream rather.

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So how can they know that?

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So for example, you can see that it is the video is coming to this shelter and then this other them

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multicast.

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So how can those the wrapper to another SRI knows how to reach to that router one day on the multicast

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because we have that on the pin on my stick which is Pim Sam The multicast will not be flooded unless

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this sort of received some information saying that they want the multicast.

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So how can those strategies know how to react to that?

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RATHER Well, the solution is to like the one of the router to be the r.p, which is, we call it,

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or rendezvous routers.

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So this will solve the problem.

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What does it mean that you can just come here and say, I want Rother wan to be the r.p?

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Then all those shorters relative to another shoe will know how to react to this r.p.

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We will see later how we can do that.

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But we have to tell to relative to the R.P is not going to want to have to tell to rather see that the.

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He is not the one.

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And also, we need to use the unique cash routing to allow those shoppers to reach to the R P, something

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like OSPF or Stuttgart or whatever.

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Because say that you have many offers after that.

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So how can those shoppers now and wish to rather one, we need to make some unique assortment vehicle.

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So those shoppers which are over here know how to reach the IP address of this shopper, which is the

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r.p in this case.

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All right.

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So now if we look to this picture here, the multicast traffic not for worried because no one is interested.

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So at this moment, say the drop of two out of three did not send anything to rother one, so rather

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one.

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Even though that he's receiving a multi catastrophic he will not forwarded to rather to and throughout

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the.

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Now say that the hospital over here want them off the cost.

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So the cost was sent agent B John which is the membership report he will send it to are out the street.

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So rather she will say oh they want multicast.

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So I have to inform the r.p that to start flowing for me the multicast.

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So rather she would send something called Ben.

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John.

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So Ben John will normally come from the rather so AARP John John come from the hospital comes from the

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rather and rather she was sent the payment John to a router one ask him that he wants to receive the

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multicast routing.

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One will recognize that the has received the payment.

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John 4239.122.3.

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So what it does it start flooding here the month the Castro she I'm going to forward multicast traffic

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to those 29.1.2.3.

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And she would go he start sending that to wrath of Sri rather she would send it to the hostel and hostel

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would be able to see the multicast streaming that is on this video.

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So that is how it works.

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So remember that we need to elect or we need to put one of the authors to be the rendezvous.

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And we need all of those other actors to know how to reach to this rendezvous.

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Because once any of the hosts that are connected on their network, on the streaming, they should be

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able to reach to that r.p.

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And to reach that r.p we have to configure on the background a unicast in protocol, something like

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a rip or a spoof or even static role.

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That's not a problem to ever to reach to that.

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RB And every time the host them the multicast, he will send the IGP a query as we have senior IGP John

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and thereafter would send the pin join to the army asking him to provide him the multicast.

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Oh, that is all nice.

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That is all very good.

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But what if this solider is not directly connected to the streaming video?

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So we have a rather in between, but this sort of still need to be the RB.

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So what's going to happen?

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How can this router will receive the multicast from the streaming video?

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So let's see that in the upcoming slide.

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So I have said that let's imagine that the IP we are have decided to have this network.

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We decided that the output would be a drop of five can see over here and not the five is not directly

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connected to this multicast streaming server.

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We have rather one in between and we have this network.

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So how can the there five?

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Because all those shoppers will communicate they're out to five to provide them the multicast traffic,

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but rather five is not connected to the streaming video directly the streaming server.

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That means that rather one has to send the multicast to a router five.

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So we have to see how this is going to work.

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But before we do that, let's see in which cases the router needs to communicate with the IP.

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There are two cases that the author needs to communicate with.

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The first one that we already know, which is the second part.

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Each part of that want the receive the matter catastrophic.

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We go to the IP.

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That's something we know only or out of that one to have the traffic of the multicast that will send

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the beam adjoin to the IP asking him to provide them the multicast.

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That's something we already know.

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But there is another case that the routing needs to connect to the IP, which is we have it in this

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case on those three devices each rather that received multicast traffic from source will forwarded to

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r.p.

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So like this router he received the multicast traffic from the source that in this case he has to send

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it to the r.p.

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So that's also very important that you put a mind where and when the routers would have to communicate

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to the operator.

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So let's take this and see and the background what's going to happen, how the communication happened

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between there also one and of five to forward the traffic of the multicast.

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So we have now to dig more in details about the case that we have seen, which is over here.

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Server, rather one and one out of five.

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So we have here two cases, possibly the tractor five does not want the streaming because no one want

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the streaming from dos rather so it didn't receive any permission.

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So in this case, we have to see what's going to happen and it goes up to five on the streaming.

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Also, how can this be forward?

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So let's have a look.

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So do even more go in deep about what is happening in the background.

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But what about the one and the other five, which is the IP router?

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Let's imagine that no one and they're not really interested in the multicast traffic.

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Now what's going to happen?

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Rather one will only send the first month expected to the IP.

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This packet is encapsulated in a just as measured and forwarded to the RBA as follows.

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So what's going to happen here?

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These are severe after one dramatic cost and that he encapsulated in a primary just a message to the

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RBA.

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So it just sent the pin resistant message to the AP asking him, do you want this multicast traffic?

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So the first option, what's going to happen at that?

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Maybe the router five does not want the multicast because it didn't receive any permission.

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So look what's going to happen in the background than Dan Rather five which is the r.p would send them

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resistors stop.

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So say to him that no one is interested in this multicast, stop sending me this traffic.

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So no, I want the multicast rather five which is the R.P.

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Send the PIM resistors.

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Stop saying no, I don't want to mount the gas traffic.

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No one wants this.

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Now what's going to happen here?

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That routing one will remain silent and start a suppression timer as far.

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So once you receive the PM resistor stop from Wrath of five, what's going to happen here?

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Rather one would say I got from RB a pen resistor stop so I'll stop for now and will start at memory

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just of suppression time.

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So just wait.

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Make suppression time so it doesn't send anything and that the suppression timer to the router five

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so that's the first case once said the ratified does not want the multicast once the suppression time

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is finished, that other one was sent another bin registered message.

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So also he would send another pair register matches, but this time he doesn't carry the encapsulated

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markets up multicast.

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It's just a simple request asking the RPF is interested in the matter.

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Catastrophic.

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So once this timer is finished, Don, he will send also a PIN registered message, but they will not

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encapsulate the multicast traffic inside of it.

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Just send them simple message saying, hey, wrapper five do you want to now want the multicast traffic?

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Now the packet that is sent is called pin resistor null.

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So that's the packet that routing one was send it to write the five same in case there are other r.p

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is not interested in the multicast traffic.

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He was sent memories just to stop.

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Also, if he doesn't want the multicast because no one from other authors want the multicast he send

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the PEM resistor stopped on other one.

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Now it goes south.

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One doesn't hear the primary, just a stop message.

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So in case he does not get the PIM resistors stop from Rata five, then it will start forwarding the

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multicast traffic.

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All right.

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So that's what's what's going to happen in the background.

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So remember, if we make a small review again, so say that that we have this video streaming to our

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other one, rather one we sent them resistor message asking if they want the multicast.

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Now, if the r.p does not want the multicast, who was the Pim resistor?

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Stop is saying to him, I don't want the multicast now, don't send me the multicast.

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So in this case rather one will make a suppression the timer and he will not send any thing to the wrath

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of five.

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And this is suppression the timer.

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Then what's going to happen that once the timer is finished, then he will send him another message.

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But this time he doesn't carry the encapsulated multicast packet.

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Just a simple message asking him if you want them off the gas traffic.

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Now the bucket that isn't it is called been registered now so this one them register so same in case

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the author five does not want the multicast.

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So what should the IP that he was handed them which is to stop the router.

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What it goes through one does not hear from are out of five defenders just to stop that the router wan

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was stopped forwarded to the multicast subject to rocket five.

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Now let's say that now in our case we have Hotshot here.

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He has sent the IP membership report to a relative asking that he wanted multicast so rather six receive

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the AGP membership report that he was I should send it to the r b now router six.

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How can we know how to reach the IP?

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Others of the r.p?

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We said that we should run a good background.

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We should run some routing protocol, unicast socket protocol like Hpf or rep or even start the crowd.

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That other signals that I have to send the the request to router four then he will send them join other

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for he knows how to reach two r.p also from the unicast routing protocol he was handed Pim John to or

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after five that in this case was going to happen.

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The traffic will be flowing from the video down to router one, two out of five and so forth.

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So all of this mechanism is called RTT root path three, Route plus three, where the IP is the root

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of our three and his and he decided where to forward the multicast traffic.

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So all this concept is called r b.

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So at the end we have this scenario, the traffic of the microcosm flowing down from routing one to

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r.p and then to a down to the R4, to our source and to the host.

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Oh, that's a lot of explanation about the append, but it's very important that we understand it because

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once we understand the concept, then we can now make a configuration.

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And without any problem you see that the configuration of them is not that difficult when we do the

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loop so that this all what I wanted to show you in this lecture, I hope now BIM is more clear for you.

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And in the upcoming lecture we have to start doing the lab.

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So see you in the upcoming lecture.