Time
31 hours 29 minutes
Difficulty
Beginner
CEU/CPE
30

Video Description

Routing Tables This lesson continues the discussion on routing tables. Routing tables determine where to pass on data. They include information such as the destination network and subnet mask and how many stops, known in networking as 'hops' it takes to get to their destination. Protocols help routing tables determine the fastest path.

Video Transcription

00:04
So
00:05
that's some of the basic information about our routers.
00:08
They move data managed these routing tables and their set is our default gateway. Well, let's look a little bit more at our routing tables. Well, are rounding tables. We talked about how they help our route and nowhere to pass on data
00:20
and our routing tables include information such as the Destination Network. I pee in sub net mask. So if we have China send a packet to a particular network, were trying to send a packet to a particular server. And we say, OK, router. I don't know where the server is. It's not on my network. It's not on my link. Where do I send this to?
00:41
We send it to the router and router says, Let me check my writing tables. Okay, This I p address matches an I P. Address
00:51
over here because I know this I p address. I know the network. I pee in the sub net mask that this other router handles. So I'm gonna pass this along over here. Or maybe it's a network that's connected directly to me. So our router needs to know the the Destination Network Net Network I d I p
01:10
Network needs to know the network I p
01:11
and also needs to know the sub net mask to know what addresses are in that network. So
01:19
that's gonna be our destination network. I pee in sub that mask.
01:22
Our routers also need to know the next router to get there.
01:26
It's not just enough that our routers say, Oh, yeah, I know what I p address network, this servers in
01:34
what next?
01:36
Our routers need to know the next router that they send that that packet, too.
01:41
If we have
01:46
our network here,
01:48
we're gonna have a computer over here
01:52
that's connected to our router.
01:59
And then this router is connected to
02:01
two other routers,
02:10
and this top router up here
02:15
is connected to the server that we're trying to get to.
02:21
So we send a packet to r R router and we say, Hey,
02:27
I need to get to
02:29
1 92.1 68.1 dot seven.
02:35
My computer was named by my computers. I P address, by the way, is 1 92 not 1 68 dot
02:43
3.15.
02:46
So I need to send this packet here
02:49
to 1 92.16 th that one by seven.
02:53
Well, my router is gonna check. It's riding tables and it's going to say, OK, well,
02:58
I have a
03:00
Can I have a network over here
03:02
that I know I can get to
03:05
that its network, I D is 1 92 dot
03:08
it's network ideas 1 92
03:13
not 1 68.1 dot
03:16
whichever
03:19
1.0
03:21
and then it's some That mask is
03:24
2 55.2 55 to 55.0.
03:30
So hey,
03:32
I know how to get there.
03:34
1 92.16 th that 1.7 is in this range of 1 92.1 68 1.0 with a sub net mask up to 55 to 55 to 55 0
03:43
That's my network. That's my computer network I D. And that subject mask indicates to me that this network contains computers that range between 1 90 feet at 1 68 1.0 through 1 92.1 68 dots,
03:58
1.2 54
04:00
so I can get there
04:01
and the i. P address of the router that I need to get to
04:06
is
04:10
this one.
04:12
So
04:13
are it's not just enough that our router knows the destination network. I pee in sudden it mask. It also needs to know the next router to get there.
04:20
It also helps that all rounder knows the number of hops to get there. Now
04:27
you may be thinking, Well, I thought they only used hops in fermentation. Well, we also use hops and networking. Two. It's a different kind of humps. See, there are lots of puns with networking. That's why it's one of my favorites.
04:38
Um, hops have to do with how many other stops we need. We need to stop it. How many checkpoints we need to stop at before we get to where we're going.
04:49
We jumping on the Beltway and are we jump on the Beltway and am I going straight there or am I gonna hit a few red lights on the way? Am I gonna hit a few other routers on the way and have to pass this message along?
05:00
Those are my different hops. For those of you that may have taken military flights before they refer to, they have different humps where you stop and you train changeover to different plane and you go on to your next hump,
05:14
your next leg of the trip or a layover for some of you that may have just taken standard flights around the world anywhere you may have a layover.
05:23
So if I'm talking toe one router and that router is only hitting one Maur router before it hits my location that I only have one hump I've got. Well, I had my router plus one hop to get to where I need to go. So knowing the number of hops helps because, hypothetically,
05:41
I'm not going to draw the rest of our network over here. But let's see,
05:45
we have
05:46
multiple other routers which connect the multiple other routers which eventually connected back to this router.
05:53
It be better for my router to know Hey, I only have one hop to get to here and then on there, or I have seven hops to go around the world
06:02
to get there to get there.
06:04
I'm gonna take this path with this one. Hop. Now again, we mentioned that we have different routing protocols which indicate to us the best way to get to a different router. But in this case, we're just taking hop count into consideration and we will discuss a routing protocol which just takes hot counts into consideration.
06:24
But
06:26
for now, that's gonna be why we know how hops are important because it lets us know the number of routing Ratter stops we get to before we get there.
06:35
There are others. Other informations that are rounding table may also pick up. And our routing table may keep depending on which protocol it uses to set its routing tables and may also take things and save information such as round trip time. How long it takes a packet to get from me
06:55
to this router. Back to me.
06:57
What's my round trip time? What's my leighton? See? What is the ban with that? I can push over this connection. How much data can I send it once over this connection? So this is all information that our routers take into consideration.
07:10
If we want a view, our computer routing table, because our local computers do have routing tables, are local computers need to know how where they send data, especially on our local network, in order to get somewhere how to you know where they need to send this packet In order to get to this server to get to this computer
07:30
that's inside of our router domain that's inside of our network.
07:33
We can go to a command prompt and simply type in route space print. And this will show us a lot of different information about our local routing table. Not nearly as much information as if we would actually go and view our routers routing table, but still a good idea as far as what a routing table looks like.
07:51
If we see when we look at our routing table in our computer route print
07:57
and we see in on link connection that's talking about a connection that were directly connected to, say, threw a switch or hub that weaken directly get to without having to go through a router. So it's data like that that lets our computer no. Hey, I'm gonna check my routing table for the server, and it looks like I have this on link,
08:16
so I don't need to send this packet to my default gateway.
08:20
I just need to send it out to the switch and the switch once it hits there is going to be able to correctly route this packet well, correctly. Send this packet to the Mac address. It needs to go.
08:31
So that's why
08:33
if we actually cleared our computer routing table, it would take our computer a little while in order to regenerate all that information so that it could start sending packets smoothly again. So round tables are very writing. Tables are very important, not just for our routers, but also for individual computers and individual nodes. And,
08:52
um,
08:54
you always want to be very careful when you're doing rounding table wanted vacations, and you always want to get the permission of God himself. Before you go on to a router and clear out a routing table because you may go on to a router, clear out a routing table,
09:11
and now you have 1000 people who can't connect anywhere
09:16
because that router doesn't know where to go,
09:18
and if it may take it a long time, it may take it a while in order to start re establishing connections in order to restart reestablishing routes and saying, OK,
09:28
this needs to go to this router to this router to get to hear this needs to go to this route to get to this router, to go, to hear this needs to, and you get the idea
09:37
depending on the protocols that were using with the other route routers and our networks, depending on how much. How many routers and other routers that that particular router is connected to are all factors and how long it'll take that router to regenerate its routing table. But again,
09:54
always double triple quadruple check always know what you're doing and have other people with you there when your modifying, routing tables and especially on high traffic and main routers
10:11
when you're trying to do static changes are manual changes into those routing tables.
10:16
So
10:18
last bit here we have here that we've hit on a couple times. Our protocols help us to determine the fastest path our protocols help us to determine. Okay,
10:28
even though this has a lower hop count, this way has one more hot count but higher bandwidth. So it would be better if I go this way or this way, has less hot this way, has higher bandwidth but has way too many more hop counts. So I'm just gonna go this way so we'll talk about a protocol is a little bit later.
10:45
We'll talk about each of our protocols individually.
10:48
But over this these couple sections we identified some of the major points with our routers what our routers do, how they move data across different networks, how routing tables work and the different between our static or a manual routing table in trees versus our dynamic routing table entries that are created using our protocols.
11:07
Um,
11:09
why we set our routers as our default gateway and information more information on our routing tables, not only on our routers but also our computers.
11:16
So let's go ahead and move on to our next segment of next top.

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