Everyone that might have that here again in this lecture I'm going to speak about the packet flow in
my critique and that's really an important topic to understand because when you know the packet flow
how it works then it becomes very easy for you to implement the one you want to do any type of firewalling
or Mangga rules or you want also to use the quality of service that all this happens inside the pie.
So it's very important that you understand the backflow and Mike think how it works and everything else
comes very easy.
And that's the reason why the Course name is traffic control OK.
So let's look what we have here.
So that is the packet flow that we have from Mike that if we look at it at first instance we can say
okay that's very complicated What is this.
I cannot understand what does it mean.
And also I was one of you that also at the beginning I was looking at it as like OK Can someone explain
to you how this works.
Because it's very complicated.
I don't understand anything in how the packet is flowing from one box or another.
But when I made it into small pieces and I took the pieces one by one and then I look at that that I
could understand how the flow is happening.
So if you look here this is the backflow that we have here and I'm going to call the each of the boxes
you see here.
I'll call them boxes.
OK.
So you can see that you have over here well the boxes we call it the lock and process.
And on this box over here is where all the process inside the router happens.
OK.
And then you have this box here.
This is the routing box.
This box here is the empty glass box and this box here is the bridging box.
And we are going to take those boxes one by one and we expand them.
Of course I'm not going to do the appeal because in this lecture I'm going to speak only about the routing
and the bridging because that's mostly used on Mike Vick if you want to know more about that.
Then then you have then to see it yourself.
But with my panache about the routing and the regime you'll be very easy for you to understand also
how the puck flow when you use the others.
So if we thought those boxes over here and we make them into one way so we can look here this is how
it looks like you have the local processor box you have the routing box which is Naisi you have the.
They have to bunk five cars and they may switch between the two and less.
And you have the bridging box which is they are two and then here you have what we call the interface
the Constellation.
And here is the out interface encapsulation.
So this really represents what it was here.
So I just made it that simple so you know what is happening on each of the boxes so if we go back here
on the locker process that's where the process of the packet happens inside the mine.
So that is in the lock up process on the resulting layer.
That's where the routing happens when you for example you are sending traffic from your network to another
network as an example.
This is where the happen on the routing layer.
So this is where the decision of the last three happened and Bill is here also in case you are configuring
us.
So in this box all the decision happened.
And if you are having for example a bridge like all your ports inside the bridge and you're sending
from or the number you do not want to port it to do that this is where the decision of the bridging
happened.
OK.
So let's take the pieces one by one and then we'll see how they look at that.
So if we go now to the make it a bit simplified so what I've done here.
So I took out the ambulance S and I think if you go back here to the first picture so you can see here
we have here and there that's traffic.
And and what we have here is ampere us all together to get out.
And then I took the capture nation and here the out the encapsulation and I made it simplified to only
have the routing and the switching.
So we go here and we see this is how it looks like.
So we have the box which is for bridging the two and we have three around thing and that is how it looks.
It's much simpler now because we are going to do some examples about the routing and about the bridging.
OK.
And over here we have the lock up process that's something we have to keep it because again that's where
the process of the packets happen inside the crowd.
OK.
Now we are going to dig into each of those boxes and see how they look like.
If we go first to the routing because the router.
My critique is a router or.
OK.
So we work first on their office so I will take this piece over here the routing and look how close.
So this is the real way that it looks.
So if I take the spottier this one this is the routing.
And this is the box which is here.
And if you look for the main picture you can see this is the routing so here that is the routing.
So you can see that I have taken this picture over here and I have put it here so you can see it's the
same one.
So that is the wrong thing.
So what happened here.
That's when the traffic comes to here that it will say Are you in traffic or you are not.
And I got that if you are an IP traffic means that it's going to another IP that go into this process
over here.
And this process so this box has also a sup process inside of it.
All right.
So this process has a process and if we want to we can look at it here.
So I will open this up process.
So does this do something.
So I took that picture and this house looks likes as a sop process so we can see that the the routing
decision has inside of it subprocess and you can see it has rerouting it has.
I think the person I'd be set policy routing forward and so forth.
So in my case I'm not going to use IP.
SEC.
OK so I'm going to take out the IP stack.
But just to mention that this process also has a sap process inside of it.
And that's what we call the chain.
OK.
So this if we want to see how it looks and then if we go here then we can see that we have taken the
IP out.
So I took out the IP set then the routing decision.
This box will look like this who have pre-roll thing.
You have the forward you have to push out the input output and the routing decision.
Now as I said inside the routing here there is also inside this sub process there is a process called
chain for example pretty routing if we go here to represent this spot in a road routing connection tracking
mangled routing and this nation that that means if we go back to the picture that when the traffic is
coming to the protracting over here then you can look here on the chain and you say OK on the priority
chain Well I want to for example make a for example in Mangu that you know that you can do in Mangere
room inside the rerouting chain and do all possible to make an mine.
OK.
So that's important to understand because then you can see every time that the packet arrive to a chain
then you can do what you can do inside this chain as you can see here inside those chains there are
a lot of information for example the road pre-landing that's where you can make some rules.
Then it's before it arrives to the connection tracking so you can for example first of packets on the
rope without them.
And then the connection tracking isn't responsible for the IP firewall.
As an example.
So that means that before it arrives to the firewall then you can stop some packet on the road rerouting.
OK you can do for example Mango you can do this generation.
And of course we have to check all the other chain as well.
They put the forward to operate at the bus stop.
But something important to mention that you can see that mangle rules are always before the rules and
before the now you can see here we have the mango rule here before the destination.
We can look here.
The Mengal impled inside the chair is before the filter impled which is also in the food chain.
So it's before the firewall and mangled forward as before.
Also the filter on the floor the manga outpolled is before the filter on the output of the mango post-rock
thing is before Denot of on the starting chain.
So you can see that is everywhere and Man-God is important because on the mango You are making some
labeling on the on the connections and on the packet.
And that's something you can use it for the one you want to do filtering as an example or when you want
to do quality of service as well.
So those are the chain that means if we look back here to this graph Let's see if for example the packet
came to the routing.
We didn't do anything and go to the routing decision that it's a four way means just going to another
IP as an example.
So when it comes to the forwarding.
And you say what I want to block the packet forwarding.
Then you can look through the chain of the forwarding and then you can see OK for where they can I block.
Then you can see and you can say yes I can I have a full auto forward here.
Then you can create a rule on the on the forward chain.
Then in this case you can you can block the traffic going forward to somewhere else.
So that's very important to understand these packet flow because it makes your life easier.
OK.
So this is what I wanted to explain.
So if we go back here to do a routing so we see here that we took the routing box and the route in box
looks like this.
And this has a subprocess and this is a process and it has inside of it IP stack.
So what I've done here I have taken how I set to make it look better and then then inside this process
of the routing are also the chain and that's the chain that are available and you know when the packet
arrives to any of those chain then what you can do you can do filtering you can do mangle you can do
now you can do whatever you want.
OK.
And based on what you see here and here are the chain rerouting input for output or something and each
one has a function inside of it.
OK so what I want to do I will use this routing after being shipped to 5 and I'll put it back in the
normal chart that we showed at the beginning.
But before I do that let's move to the bridging because we said we need to see the routing and we need
to see the bridging.
So this is the bridging part and also if you want we can go to the first one so I'm taking now this
one the bridge and park which is this one here so you can see that is how it looks so I took this box
and now it looks like this.
So that is the box the same one but I just took it by itself.
And inside this box also there is a subprocess.
So it is the process of the breeching.
OK.
So as you can see I make it a bit bigger.
So this is the subprocess.
Do you have a bridge destination that you have for print.
We have here the firewall the rerouting which include the bridging decision and so forth.
So to make it simple Also the bridge you have inside the bridge what we call the IP firewall.
That means that if the packet is going inside the bridge so say to Boston in a bridge and it's going
from one for to another four but there it is inside the same bridge.
So the two boats on the side the same bridge what you can do you can make it also firewall inside the
bridge by enabling the IP firewall.
But most of the time we don't need that because we have the firewall on Layer 3 so I don't want to really
to do I'd be FEIBEL inside the bridge itself.
So to make it easy I have decided to take those IP firewall here to remove them.
Those ones that I have only the bridging that's OK to make it simple.
So after I took out the IP firewall.
Now if you want to put the routing and the bridging together that is how it looks.
So this picture is that is the bridging after we took out the IP firewall and did the routing after
we took out the IP SEC and of course this looks as this one this one.
So what I've done I just made the bridging and routing simplified and then I added them here and now
it looks like this.
OK.
So this is the packet flow for the routing and for the bridging again on the routing first we took out
the Ampere us when we looked through the packet flow.
We took out the encapsulation the the operation and then I took each box by itself and made them simplified
from routing I took out the IP stack and we've seen in the routing there are also some processes which
are the chains and then from the bridging I took out the firewall.
And I made it simplified and then I added here and now we have the backflow for the routing and for
the bridging.
So for now what we have is more a simplified way that the though how it looks like.
Now I need to do examples.
I'm going to do five examples for all the drafting and the bridging to show you how fast the package
is flowing when you want to send it on the mike.