I know that this might have that here again.
So in this lecture I have to give explanation about Penn.
So them is the protocol independent multicast, which is the we have to call it something like the multicast
routing protocol.
So set first that we forget a bit about BIM and we just think about the route protocol that we normally
know.
So say that you have this network and it also want to send traffic to one or two.
I say to the two, which is this computer on the unit cached routing, what's going to happen that once
this traffic comes to router two, router two will open his talking table, which is over here at Hiroshi?
Do I have any entry to reach through one or two?
I say the two, the two.
Then he will look at me, say, Oh, I have one answer here saying that to go to one or two, I say
the to the zero network, which is the network of one or two, I say go to the two, then I have to
send everything out of my interface internet two because this is directly connected to me.
Then Router two will know that he has to send the traffic like this.
So that's something we know about routing in unicast.
So that's what we are talking about unicast.
So what is going to happen when we speak about the multicast?
So we have this scenario, we have this video streaming and we have this computer which is the receiver.
And we said that the on the multicast we always send to a group multicast group which is something like
239.1.2.3.
So this is the destination and this source is coming from the server which is one 7216 .1. 100.
Now this traffic will come to the outcome.
If we think about the unicast, the delta, what he has to do this is to look to his drafting table
and he has to see if he knows about the destination, which is 239.12 to the stream.
Then if we look on his routing table, that is his routing table.
Look, he doesn't know anything about two, three nine.
The one, the two, the street.
He knows about one.
So 216 12. 68i want to do a set of data point here too.
So he knows those are from connected, that is from ICF, but he doesn't know anything about the multicast,
which is 239.12 to the stream.
So you can see you say I have no clue where to forward what the catastrophic two and what's going to
happen if you did not configure something like BIM then the traffic will be discarded.
That would be dropped completely and then this computer over here would never received the map, the
catastrophic.
So to avoid this, we need to have some mechanism and the mechanism that we need to use is spend that
I'm going to explain to you in the upcoming slide.
So then which is on my could take them as Spanish mode.
So that's the mode that migrated to use because that is another mode called dense mode.
That's something you can see on some other vendors like Cisco.
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
counter Dorado is only for work to map the catastrophic one another rather request for that traffic.
So that's something you have to keep in mind that the once you configure PIM in case the router received
requests from other operators, you want them out there.
Marcos then he was sending multicast.
If he doesn't receive anything, then he doesn't show that they're multicast.
While Pim de am which is on Cisco.
The Dutch more than the multicast is always flooded once received.
So once the multicast comes to the upstream interface, then it will always be flooded.
However, at this moment there's not a variable on my dick, so the only option that we have is Pim,
as I have said, which is in my opinion it's more scalable than than the.
So my colleagues have done a very good job to just put them aside because in my opinion that business
is better than the team.
The now we have a question that may come to the mind, which is how can the routers or other authors
know how to reach that dropper if they want the multicast offer?
So that means the rafter, which is the upstream rather.
So how can they know that?
So for example, you can see that it is the video is coming to this shelter and then this other them
multicast.
So how can those the wrapper to another SRI knows how to reach to that router one day on the multicast
because we have that on the pin on my stick which is Pim Sam The multicast will not be flooded unless
this sort of received some information saying that they want the multicast.
So how can those strategies know how to react to that?
RATHER Well, the solution is to like the one of the router to be the r.p, which is, we call it,
or rendezvous routers.
So this will solve the problem.
What does it mean that you can just come here and say, I want Rother wan to be the r.p?
Then all those shorters relative to another shoe will know how to react to this r.p.
We will see later how we can do that.
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.
He is not the one.
And also, we need to use the unique cash routing to allow those shoppers to reach to the R P, something
like OSPF or Stuttgart or whatever.
Because say that you have many offers after that.
So how can those shoppers now and wish to rather one, we need to make some unique assortment vehicle.
So those shoppers which are over here know how to reach the IP address of this shopper, which is the
r.p in this case.
All right.
So now if we look to this picture here, the multicast traffic not for worried because no one is interested.
So at this moment, say the drop of two out of three did not send anything to rother one, so rather
one.
Even though that he's receiving a multi catastrophic he will not forwarded to rather to and throughout
the.
Now say that the hospital over here want them off the cost.
So the cost was sent agent B John which is the membership report he will send it to are out the street.
So rather she will say oh they want multicast.
So I have to inform the r.p that to start flowing for me the multicast.
So rather she would send something called Ben.
John.
So Ben John will normally come from the rather so AARP John John come from the hospital comes from the
rather and rather she was sent the payment John to a router one ask him that he wants to receive the
multicast routing.
One will recognize that the has received the payment.
John 4239.122.3.
So what it does it start flooding here the month the Castro she I'm going to forward multicast traffic
to those 29.1.2.3.
And she would go he start sending that to wrath of Sri rather she would send it to the hostel and hostel
would be able to see the multicast streaming that is on this video.
So that is how it works.
So remember that we need to elect or we need to put one of the authors to be the rendezvous.
And we need all of those other actors to know how to reach to this rendezvous.
Because once any of the hosts that are connected on their network, on the streaming, they should be
able to reach to that r.p.
And to reach that r.p we have to configure on the background a unicast in protocol, something like
a rip or a spoof or even static role.
That's not a problem to ever to reach to that.
RB And every time the host them the multicast, he will send the IGP a query as we have senior IGP John
and thereafter would send the pin join to the army asking him to provide him the multicast.
Oh, that is all nice.
That is all very good.
But what if this solider is not directly connected to the streaming video?
So we have a rather in between, but this sort of still need to be the RB.
So what's going to happen?
How can this router will receive the multicast from the streaming video?
So let's see that in the upcoming slide.
So I have said that let's imagine that the IP we are have decided to have this network.
We decided that the output would be a drop of five can see over here and not the five is not directly
connected to this multicast streaming server.
We have rather one in between and we have this network.
So how can the there five?
Because all those shoppers will communicate they're out to five to provide them the multicast traffic,
but rather five is not connected to the streaming video directly the streaming server.
That means that rather one has to send the multicast to a router five.
So we have to see how this is going to work.
But before we do that, let's see in which cases the router needs to communicate with the IP.
There are two cases that the author needs to communicate with.
The first one that we already know, which is the second part.
Each part of that want the receive the matter catastrophic.
We go to the IP.
That's something we know only or out of that one to have the traffic of the multicast that will send
the beam adjoin to the IP asking him to provide them the multicast.
That's something we already know.
But there is another case that the routing needs to connect to the IP, which is we have it in this
case on those three devices each rather that received multicast traffic from source will forwarded to
r.p.
So like this router he received the multicast traffic from the source that in this case he has to send
it to the r.p.
So that's also very important that you put a mind where and when the routers would have to communicate
to the operator.
So let's take this and see and the background what's going to happen, how the communication happened
between there also one and of five to forward the traffic of the multicast.
So we have now to dig more in details about the case that we have seen, which is over here.
Server, rather one and one out of five.
So we have here two cases, possibly the tractor five does not want the streaming because no one want
the streaming from dos rather so it didn't receive any permission.
So in this case, we have to see what's going to happen and it goes up to five on the streaming.
Also, how can this be forward?
So let's have a look.
So do even more go in deep about what is happening in the background.
But what about the one and the other five, which is the IP router?
Let's imagine that no one and they're not really interested in the multicast traffic.
Now what's going to happen?
Rather one will only send the first month expected to the IP.
This packet is encapsulated in a just as measured and forwarded to the RBA as follows.
So what's going to happen here?
These are severe after one dramatic cost and that he encapsulated in a primary just a message to the
RBA.
So it just sent the pin resistant message to the AP asking him, do you want this multicast traffic?
So the first option, what's going to happen at that?
Maybe the router five does not want the multicast because it didn't receive any permission.
So look what's going to happen in the background than Dan Rather five which is the r.p would send them
resistors stop.
So say to him that no one is interested in this multicast, stop sending me this traffic.
So no, I want the multicast rather five which is the R.P.
Send the PIM resistors.
Stop saying no, I don't want to mount the gas traffic.
No one wants this.
Now what's going to happen here?
That routing one will remain silent and start a suppression timer as far.
So once you receive the PM resistor stop from Wrath of five, what's going to happen here?
Rather one would say I got from RB a pen resistor stop so I'll stop for now and will start at memory
just of suppression time.
So just wait.
Make suppression time so it doesn't send anything and that the suppression timer to the router five
so that's the first case once said the ratified does not want the multicast once the suppression time
is finished, that other one was sent another bin registered message.
So also he would send another pair register matches, but this time he doesn't carry the encapsulated
markets up multicast.
It's just a simple request asking the RPF is interested in the matter.
Catastrophic.
So once this timer is finished, Don, he will send also a PIN registered message, but they will not
encapsulate the multicast traffic inside of it.
Just send them simple message saying, hey, wrapper five do you want to now want the multicast traffic?
Now the packet that is sent is called pin resistor null.
So that's the packet that routing one was send it to write the five same in case there are other r.p
is not interested in the multicast traffic.
He was sent memories just to stop.
Also, if he doesn't want the multicast because no one from other authors want the multicast he send
the PEM resistor stopped on other one.
Now it goes south.
One doesn't hear the primary, just a stop message.
So in case he does not get the PIM resistors stop from Rata five, then it will start forwarding the
multicast traffic.
All right.
So that's what's what's going to happen in the background.
So remember, if we make a small review again, so say that that we have this video streaming to our
other one, rather one we sent them resistor message asking if they want the multicast.
Now, if the r.p does not want the multicast, who was the Pim resistor?
Stop is saying to him, I don't want the multicast now, don't send me the multicast.
So in this case rather one will make a suppression the timer and he will not send any thing to the wrath
of five.
And this is suppression the timer.
Then what's going to happen that once the timer is finished, then he will send him another message.
But this time he doesn't carry the encapsulated multicast packet.
Just a simple message asking him if you want them off the gas traffic.
Now the bucket that isn't it is called been registered now so this one them register so same in case
the author five does not want the multicast.
So what should the IP that he was handed them which is to stop the router.
What it goes through one does not hear from are out of five defenders just to stop that the router wan
was stopped forwarded to the multicast subject to rocket five.
Now let's say that now in our case we have Hotshot here.
He has sent the IP membership report to a relative asking that he wanted multicast so rather six receive
the AGP membership report that he was I should send it to the r b now router six.
How can we know how to reach the IP?
Others of the r.p?
We said that we should run a good background.
We should run some routing protocol, unicast socket protocol like Hpf or rep or even start the crowd.
That other signals that I have to send the the request to router four then he will send them join other
for he knows how to reach two r.p also from the unicast routing protocol he was handed Pim John to or
after five that in this case was going to happen.
The traffic will be flowing from the video down to router one, two out of five and so forth.
So all of this mechanism is called RTT root path three, Route plus three, where the IP is the root
of our three and his and he decided where to forward the multicast traffic.
So all this concept is called r b.
So at the end we have this scenario, the traffic of the microcosm flowing down from routing one to
r.p and then to a down to the R4, to our source and to the host.
Oh, that's a lot of explanation about the append, but it's very important that we understand it because
once we understand the concept, then we can now make a configuration.
And without any problem you see that the configuration of them is not that difficult when we do the
loop so that this all what I wanted to show you in this lecture, I hope now BIM is more clear for you.
And in the upcoming lecture we have to start doing the lab.
So see you in the upcoming lecture.