Hello and welcome back to I C and D one interconnecting Cisco networking devices. Part one
this is Episode 144 i p. Routing table protocols on an address. Let resolution protocol are AARP. I'm Trenton. Daryl and I will be your instructor for this course.
The last video went over the I P before address ing some rules, some classes, and we finished office. Um, binary meth. Hopefully didn't hurt you guys too much to do that binary. Hopefully figured it out. Otherwise, please go back and learn it. It is necessary for a sub net.
In this episode, there were becoming the I P routing table protocols finish up with AARP
and the learning objectives. We're gonna look at the help
I p host routing logic recap.
We're gonna look at the I P. Router look. Routing logic,
the routing protocols, overview and art
and a quick pre assessment here. What classes? The address. 1921681 not 50. Hopefully. Remember this one from the previous one?
All right. So the basic I p hosts routing or the like of your at your PC, That'll be a host
logic for it is when it sends a packet it's going to say, is this destination I pee on the same subject is me, If it is, is just gonna send it directly to that
destination. So if we look at P C zero here, get a pen out
If he wants to send a packet or two p C one,
he's just going to say, OK, gonna save so tonight, I'm just gonna send it right over here.
Otherwise, let's say he wants to go down to service zero.
What is gonna have to do is he's gonna have to say, Okay, well, and you send it to my default gateway, which is rather a
and I know we looked at it and previous lesson
the Marauder is gonna consult the routing table. Say okay to get to the 10 dot network, going to go through serial one.
Then he's gonna go through cereal, too, and he's gonna finally say, OK, I have a connected route for server zero. I want to send it through my Ethernet right to him.
a little bit about the i P router voting logic again. First thing. So when PC zero sends it to default Gateway,
you felt Gateway Router A is going to say, Okay, I'm gonna look at the frame check sequence of CS.
She was a bad frame. If it's a bad frame,
the math doesn't add up. It's just gonna discard that packet
to discard that frame.
If it is good, is gonna end of de caps. Elated. That frame is gonna look at that. I p packet that's gonna consult that rounding table again
because they okay, where do I need to go? Okay. We need to go down to the 10 dot network
and shoot it down here.
I was gonna encapsulate it with the Mac address for destination for router. Be on a source right away,
and this is gonna de encapsulate it. Look at the destination I P address. See? Okay,
we're looking at the 10 dot network.
I'm a real catch like this with a destination Mac address of router. See,
he was going to d encapsulate it. Look at the address. Say Okay. I gotta connect the drought for that.
Let's head on down the server zero.
It's one thing you guys will see here,
So this is a destination. Last resort.
So you okay if we don't match the 10 dot network sent it out to the cloud
if I actually find it.
All right, so the routing protocol or review So we're gonna get into any of the actual routing protocols yet? That'll becoming a later lesson.
But what we want is for the routing protocols. Wanted to dynamically learn their routes, right, Because of a network engineer engineer had to put input, you know,
It would, uh I mean, it would just be impossible, especially if a new one came up.
And let's say if a link goes down,
he would have to be on site to put in a new Route four to get there.
So we want our routers to build to choose the best route. If there's options, right, and then there's different ways that they'll do it. We'll go with it was later again,
but it wants to be just wanted to choose the best row. And we wanted to also remove routes when they're no longer available. Let's say a link goes down.
Then we wanted to remove that route and say OK, there's also a route to the over here that we can take.
So I wanted to add new routes, and we also wanted to do it fast, right? Convergence be That's what that is, the amount of time that it takes. We're out to learn that route is down and to find an alternate route for it to take.
And finally, we wanted to prevent routing loops
so we don't want to just to keep going in the same five routers that are just sending a packet that Did you get stuck there? Right?
It'll take down a network pretty quick.
So Rogers air independently gonna add They're connected. Route. So we talked a little bit about that with Router C is gonna have that connected route for server zero. Right? Gonna have that network and it's connected route. Then what's gonna do is gonna tell us neighbors and say, Hey, I got a network to the 10 dot over here,
which is actually gonna send through a routing update,
And then after the other routers learned that route, they're going to say, Okay, I'm gonna add that to my routing table so I can go through a router three rather see to get to the 10 dot network. Cool.
All right. So d n s. This is the domain name service. So what it does is actually binds eyepiece to host names.
That's what I mean by that. Let's see. You know, when you go to google dot com or Facebook or linked in or Cyber Eri,
you only punch in that in your web browser. What work computer does it consults the D. N s first figures out what the i p addresses for that layer three packet
and then throws that destination i p address in there.
So in case you're curious on Windows, the high peak and fig slash flush D N s actually clears out cash to a century. So if you're having issues with some of your Internet ones where you know you're like, man, it should work. But for some reason, let's say an I p change and it hasn't updated.
You could flush it and give that a shot.
Let's say someone like Host puts in www cyber harry dot com into their Web browser was gonna do is look in the cash Deena's listing on your computer first, If it's not there, is gonna ask the d n a server for the i p address
the d n. A server is gonna look up that host name and say, OK, I got the I P address for it. Here you go. And that is going to send it back to the host
when the host PC family gets the i p address for WW dot cyber dot com. That's gonna put that a destination address for that packet.
So here's a quick s look. Att off www dot google dot com
And right now we're just pulling one address, and we're also pulling a I P V six address, which will go over that later.
And next we move on to art for the address resolution protocol. So what this does it binds the Mac address to the I P address. So on Windows, have you type in AARP Dash D That will clear the cash for that.
So generally is about a five minute cash link. So once the host first comes online, what it does, it sends a broadcast out looking for that Gateway Mac address. So it can add that to the table. So that way we can get Internet connectivity fast enough
then also is gonna start looking through and say, OK, this is my I p address. I'm gonna start looking for other high pees on a network. I'm not trying.
Search sent it out. ARP request. So says, hey, is anyone at 192168 That one got 20
that one. That one got 21 start looking through all these different ARP. Request that figure out if it was there. And if people are there, they'll respond with their Mac address and that will get added to the art table. As you can see in the frame to the right
that has the i P address and then has the physical address or their Mac address.
And lastly, we're gonna have the icy appear the Internet control message protocol.
So you lot of times you used Ping
Ping is the packet Internet cropper, which actually uses ICMP.
So a lot of time, people, almost all level one helped us. We'll use this to get to see if you have basic Internet connectivity will say Okay, ping google dot com
right. If you do, you should see this.
You should see response with 0% loss.
s So what it actually does is your host is gonna send icmp echo request to that address.
So it's gonna say, hey, respond to me if you get this and then the destination say Okay, I got your request. I'm gonna sign back a reply.
So put less Pro's assessment here. I wanna have you guys do a quick look up of the I P address of cyber harry dot com.
I'll give you second, pause the video and see if you could figure it out.
All right. Hopefully you guys got this. It is actually all those addresses, or at least what I'm pulling.
And you see, when I did the ns look up here, it pulled four different addresses.
And the next episode we're gonna move on to lesson 1.5, the fundamentals of T c p i p transport and applications.
And as always, if you guys have questions or you need hope,
you're free to send me a message. Otherwise, thank you for watching this lesson and I'll see you in the next one