Time
30 hours 46 minutes
Difficulty
Intermediate
CEU/CPE
20

Video Description

Dynamic Routing As mentioned in the previous lesson, Routing table data is populated in two ways, statically meaning it's manually entered, and dynamically where routers on remote networks communicate directly with each other. This lesson examines the process of Dynamic Routing, defines what routing protocol tools are, and cleaning maps out the process by which routers from two remote networks are able to learn of each other, then communicate directly with each other. We'll explain Distance Vector Routing Protocol, the Links State Routing Protocols and their differences, as well as discuss what the Router Information Protocol (RIP) is, demonstrate what a "Hop" is, and map out this processes to show how routing through routing protocols function.

Video Transcription

00:04
So now that we're done with the process off manually, entering in routes into a routing table called static routing, where we have to manually enter the route to Metro 10 on router to one, we're gonna cover the process of dynamic routing.
00:19
Dynamic routing is the process when to routers, shared networks or remote networks or remote route or route to remote destinations. Automatic me by running these programs called routing Protocols on them. In our case, if we were running
00:37
dynamic routing on router to one route or to a one would automatic me learn how to get to Network 10 from Router one. Rather, too, would send information about Network 10 to Router one, and rather one would send information about Network 10 and how to get there to router to a one.
00:54
Now there are two types off
00:57
dynamic routing protocols. The first kind is your distance vector routing protocols and your second kind are your link state routing protocols.
01:07
So the only
01:10
pure distance vector routing protocol we're going to cover in this class is called Route Information Protocol or rip for short.
01:18
This inspector routing protocols possessed some qualities. Some common general qualities
01:23
these qualities are
01:26
when a router is running a distance Vector out in Peru calls it, sends
01:32
the contents off his whole routing table, every set interval in routing updates.
01:38
So every 30 seconds Route Information protocol is gonna send the contents off his whole routing table to the directly connected devices to it's directly connected neighboring devices.
01:51
Once again,
01:53
this inspector out on parole, send the contents of the whole routing table every set interval, and this interval is 30 seconds for rip or route information protocol,
02:05
which is not a good thing, because every 30 seconds the router next to you is getting hit by all this information, whether it needs it or not.
02:15
For once, it's already learned this information. It doesn't need to re hear it over and over again, but distance vector routing for calls send the contents of the routing table every set interval. And for rip, this interval is 30 seconds.
02:30
This inspector out in Coco's also send the routing update through the address to 55255255255 Basically the all hosts all sub nets broadcast, which is also not a good thing because everybody on the network unless there's a router president and the router blocks this broadcast
02:49
because broadcasts can't trust transfers a router.
02:53
But otherwise everybody on the network is going to hear this update whether they want to or not.
03:00
Distance Vector outing protocols also use something called hop count as their metric
03:06
Now. First, let me define what a metric is.
03:07
A metric is
03:09
the measure of distance between your local router and a remote network.
03:15
So once again, a metric is a measure off Distin's between your local router and a remote destination or the destination network.
03:25
So in this case, I've drawn out a little diagram. You see Network 10 is available to Router two and one True Router. Three.
03:36
No
03:37
using Hop Countess Metric Router to Is one router Hop away from Network 10.
03:44
The hot being router three.
03:46
Router three is zero hops away from Network 10 since it is directly connected, so Router three will send information about network 10 automatically to router to if they're running a distance, vector out in protocol
04:00
with the hop count of zero router to will incriminate that hop count to one, so Router two will be one hop
04:08
one hops. One hop away from network chin
04:13
router to will send information about Network 10 with the hop count of 12 router one and rather one will interment that hop count to two,
04:21
due to note that Roger one is to router hops away from Network 10.
04:27
Now, distance vector routing protocols are prone to routing loops
04:31
because they're out by rumor.
04:34
Now what do I mean by route by rumor? Well, from Router one's point of view. Rather, one doesn't really know whether Network 10 is actually two hops away. Or if Network 10 actually exists somewhere down here.
04:49
So,
04:50
actually, I should say, if Network 10 exists somewhere up here, so the closer to the destination network you are, that is the source. So this is upstream.
05:00
This is downstream,
05:02
so rather, one is not completely sure
05:06
that Network 10 is too router hops upstream.
05:11
It is just believing, router to and router To tells it that hey, I'm one rather hop away
05:17
and that Network 10 exists in that direction.
05:20
When we get to link state routing protocols, the other type of routing protocol,
05:26
the alternate to distance vector out in Peru calls you will see that router one will be completely aware off this link between itself and router to and the link between router to and router three and Network 10. So Router one will have an end to end view of the topology. But with this inspector routing protocols,
05:46
you just believe what the next top router is telling you,
05:49
which makes it prone to routing loops.
05:54
So let's see how routing Luke happens now. You don't actually need to know
06:00
in detail how routing loop happens for you. See CNN, you just need to know that they can happen. However, I will go ahead and demonstrate how routing room cat Luke can happen in a topology.
06:12
For that, I need to draw a diagram. Now I'm going to demonstrate how a routing Luke can happen.
06:18
So if I were to say,
06:20
Network 10 Net 10 or Network Chen is available to Router 412 and three through Router five, I would expect a resounding yes from you guys.
06:31
Router five. Let's say these routers are running route information protocol. Router five is sending its updates or its whole routing table, which at this point only consists of network 10 to router for every 30 seconds and then every 30 seconds. Router four is forwarding that information to Router one, and then every 30 seconds or out of one
06:51
is forging that information to Router to and router three.
06:56
Now from the point of view of Router three, let's look at Router three.
07:00
Network 10 is available to Router three
07:03
through Router one with a hop count off. 123
07:10
Network 10 is also available to Router three
07:14
through router to with the hot count off 1234
07:19
So hop count of three.
07:24
I'll write it here. Hop kind of three to Router one and how. Count of four through router to
07:33
now, let's say Network 10 feels this link on the router fails. Something goes wrong with that interface, and it fails.
07:44
Router five waits around for a little bit and then sends
07:48
another date to router for saying that Work 10 is down
07:54
after 30 seconds since we're running rip router foretells rah rah Juan. Hey, network 10 is down
08:01
Now, remember, Four Router three. Metro 10 is available to two part pats y our outer one with the top down to three and buy a round or two with a hop count of four.
08:13
Rather, one turns around and sends an update to Router True and Router three saying, Hey, guys, where 10 is down.
08:22
But since these updates are not synchronized, it could happen that while rather one was sending that update and that update arrived at Router three before it arrived at Router to in the meantime router to sends an update to Router three announcing that Network 10 is available to router to with a hop count of four
08:43
and now a router three also learns that Network 10 is down through Router three,
08:48
so this option gets taken away.
08:52
So router, two things about it and router three things about It and says, well before it was available through a closer distance or a closer metric with Hakan a Tree. But I have no other option, so I will go through a router to to get to Network 10
09:09
to router
09:11
three increments the hop count for network 10 to 4
09:16
and keeps it in the routing table. But now, throughout her too
09:20
router to his update from Router one. That network 10 is down
09:26
through outer one,
09:28
but Router three
09:31
at the same time sends an update to Router one saying, Hey, Network 10 is well in alive through me with the hop count of Fine.
09:45
So Router one learns this
09:48
doesn't know that it's gonna the update just came from itself.
09:52
So Router one doesn't know that if it goes to Router, three out of three will send it to Router to and back to Route A one
09:58
robber. One's view of the topology is Guru's as far as the next router over because this inspector out in Protocols Route by rumor,
10:09
Router one now learns that Metro 10 is well in alive with the hot count of five
10:13
True outer one.
10:16
Router one sends an update back this wonderful news to router for saying that Network 10 is melon alive with the hop count of six through outer. One
10:26
router of one writer four actually sends another big back to router five and Say's Network 10 is alive and well with the How count of six to router for
10:37
So basically any packets destined to that network are being black hold because they're going nowhere.
10:43
Router. One Also sense this updated received from Router three back to router to seeing Net wrote 10 is alive and well through me with the hop count of five
10:54
rotter to gets this update and goes, Hey, the hop count went up from 4 to 5.
10:58
Writer too,
11:01
Since this update two Router three
11:03
with the hop count of five and Router three instrumented to hop count of six.
11:09
This update again is sent from router 32 Router one and the hop counters instrumented and rather one turns around sense update back throughout or two. And what happens is a loop and you will constantly be implementing the hop count
11:24
which this process is called. Count counting to infinity
11:28
and eventually enough packets will jumble of this network that these routers will crash.
11:35
So that is how a routing group can happen.
11:39
Now this inspector routing protocols have an inbuilt lou prevention mechanism. Well, there are several invent built Lou prevention mechanism, so now we'll go over the distance vector routing protocol. Lou prevention mechanisms

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