All language subtitles for Free-CCNA-OSPF-Part-3-Day-28-CCNA-200-301-Complete-Course_en

Welcome to Jeremy’s IT Lab. This is a free,\n

these videos, please subscribe to follow along\n

a comment, and share the video to help spread\n

Today we will finish our studies of OSPF for\n

in much greater depth than RIP and EIGRP.\n

CCIE level, you’ll see that there is much,\n

purpose of this CCNA course we’ll finish\n

here is exam topic 3.4, which covers OSPF.\n

ready to take on OSPF questions on the CCNA\n

First let’s look at what we’ll cover in\n

These refer to the different kinds of connections\n

influence OSPF’s behavior. Next up we will\n

In day 2 we covered the process routers use\n

actually look at the requirements for a successful\n

at a few of the LSA, Link State Advertisement,\n

be aware of a few for the CCNA. Make sure\n

for a bonus question from Boson ExSim for\n

Before we get into those topics I want to\n

a little bit. In previous videos I’ve mentioned\n

them in the past few lab videos, but let me\n

is a virtual interface in the router. You\n

you manually shut it down). So, this means\n

dependent on a physical interface. Physical\n

fail, however that can’t happen to a loopback\n

So, it provides a consistent IP address that\n

Sometimes you need to send traffic directly\n

interface at the moment, and R4 receives a\n

address of its G1/0 interface. It might forward\n

What if R1’s G1/0 interface goes down for\n

for R1 at 10.0.13.1, it will not be able to\n

How about if R1 has a loopback interface,\n

of 10.0.13.1? Even if a physical interface\n

for R1’s loopback interface it will still\n

why it’s a good idea to configure a loopback\n

with an IP address that is always up, and\n

Now let’s move on to look at the different\n

refers to the type of connection between OSPF\n

behaves in some ways. The most common type\n

of course. There are three main OSPF network\n

type, which is enabled by default on Ethernet\n

and you don’t need to spend time learning\n

flashcards for OSPF network types, you might\n

the exam, that the OSPF broadcast network\n

network type, which is enabled by default\n

to learn PPP and HDLC in depth for the current\n

later in this video. The last main network\n

on Frame Relay and X.25 interfaces. Again,\n

types for the exam, but I will include them\n

OSPF network types. Take a look at the OSPF\n

network type, and 3.4c mentions the Broadcast\n

First up, the broadcast network type. As I\n

on Ethernet and FDDI interfaces by default.\n

and in the previous videos all of the OSPF\n

Broadcast network type, because they are all\n

above, these are all Ethernet connections,\n

and therefore these connections between the\n

type. Now let’s cover a few characteristics\n

dynamically discover neighbors by sending\n

the multicast address 224.0.0.5. You already\n

you how OSPF routers become neighbors. However,\n

neighbors like this. We won’t cover this\n

network type you must manually configure neighbors.\n

and BDR, backup designated router, must be\n

the G1/0 interface of R1, R3, R4, and R5 where\n

a DR, no BDR. Routers which aren’t the DR\n

I’ve heard a few ways to pronounce that,\n

at the network above. Each subnet needs a\n

neighbors so each router becomes the DR for\n

between R1 and R2? In the next slide I’ll\n

say R2 is the DR. So, R1 becomes the BDR for\n

subnet that R2, R3, R4, and R5 connect to?\n

and then R2 and R3 become DROthers. You’re\n

and what the purpose of the DR and BDR is.\n

So, here’s how the DR and BDR are elected.\n

router with the highest OSPF interface priority\n

However, all interfaces have the same priority\n

OSPF router IDs. The router with the highest\n

the election becomes the DR for the subnet,\n

default OSPF interface priority is 1 on all\n

with the highest router ID will become the\nDR for the segment.

Here’s some partial output from SHOW IP\n

ID. I configured a loopback interface on each\n

interface became the router ID. State DR,\n

the highest router ID of the routers connected\n

the DR. Down here the DR, R5 itself, and BDR,\n

their router IDs and the interface IP address\nin the subnet.

And here’s the same output for R2. The main\n

of DROTHER. Now, what if I want to make R2\n

see how to change the OSPF interface priority.

The command to change the OSPF priority of\n

by the priority, with a range of 0 to 255.\n

a side note, if you set the OSPF interface\n

for the subnet, no matter what. So, let’s\n

That’s strange. R2’s state is still DROTHER,\n

is that? It’s because the DR/BDR election\n

about ‘preemption’ in Day 29 when we learn\n

what ‘non-preemptive’ means is that once\n

role until OSPF is reset, the interface fails/is\n

idea to do in a live network, I’ll go reset\n

So, I reset the OSPF process on R5, and you\n

Then R2 and R4 returned to the FULL state,\n

for that, you’ll learn soon. Then I used\n

the neighbor state of R5’s neighbors. Look\n

OSPF we can learn by analyzing this section.\n

the BDR. What can we learn from that? We can\n

becomes the new DR. Then an election is held\n

stepped up to be the new DR, and then an election\n

next BDR. R2 has the highest priority, 255,\n

is a DROther, and is stable in the 2-way state.\n

can we learn from this? We can learn that\n

with the DR and BDR of the subnet. The neighbor\n

gives us a hint to the purpose of the DR and\n

But remember these two points, that the BDR\n

even if it doesn’t have the highest priority.\n

with other DROthers, they remain in the 2-way\nstate.

To repeat, in the broadcast network type,\n

with the DR and BDR of the segment. Therefore,\n

BDR. DROthers will not exchange LSAs with\n

routers haven’t shared LSAs with each other\n

LSDB, but this reduces the amount of LSAs\n

If 6 routers are connected to the same segment\n

will end up like this. A whole lot of LSAs\n

If routers only exchange LSAs with the DR\n

flooding around the network is reduced. To\n

not a big deal in most cases, but it still\n

By the way, when routers need to send messages\n

224.0.0.6. This is different than the OSPF\n

Here’s a quick review of the OSPF neighbor\n

steps involve becoming neighbors? So, when\n

are OSPF neighbors. Connections between two\n

only continue on to exchange LSAs and form\n

So, to summarize, this means that the DR and\n

in the subnet, including the DROthers. And\n

I showed you this command, SHOW IP OSPF INTERFACE\n

is a DROther. Notice the neighbor count on\n

of full adjacencies, and C indicates the total\n

with R2 and R4. But it has three total neighbors,\nR2, R4 and R5.

For more detail, here is SHOW IP OSPF INTERFACE\n

here, ‘Neighbor Count is 3’, that’s\n

neighbor count is 2’, those are the neighbors\n

it, its two adjacent neighbors are listed.\n

enough for the Broadcast network type for\nnow, let’s move on.

Now let’s take a look at the ‘point-to-point’\n

between R1 and R2 to a ‘serial’ connection.\n

connections in the next slide, but first let\n

connection type. This network type is enabled\n

encapsulations by default. PPP and HDLC are\n

except they are used on serial connections.\n

dynamically discover neighbors by sending/listening\n

224.0.0.5. However, here’s a difference.\n

As the network type name implies, these encapsulations\n

between two routers. Therefore there is no\n

will form a Full adjacency with each other,\n

Okay, let me give a very brief overview of\n

serial connections are an old technology which\n

but Ethernet is much more dominant. In fact,\n

the exam topics except for the OSPF ‘point-to-point’\n

tested directly on knowledge of serial interfaces,\n

This photo shows some serial interfaces and\n

cables are different than Ethernet cables.

To explain serial connections, I’ll show\n

You don’t need a deep understanding of this\n

here. First up, one side of a serial connection\n

Equipment. The other side functions as DTE,\n

Why is this significant? Well, on serial connections,\n

which is the speed, of the connection. So,\n

and therefore needs to tell R2 what speed\n

is ‘clock rate’, and then you can see\n

of these are in bits per second, by the way.\n

second, aka 64 kilobits per second, added\n

an important point. Ethernet interfaces use\n

operating speed. Serial interfaces use the\nCLOCK RATE command.

Let’s continue. I checked the interface\n

encapsulation is HDLC. On Cisco routers, the\n

is HDLC. Actually, it’s Cisco’s own version\n

as just ‘HDLC’ in the CLI. Once again,\n

except it’s used on serial connections.\n

from Wikipedia. You don’t need to learn\n

a look. One thing to note is that there is\n

aren’t used. I mentioned the PPP encapsulation\n

to use that encapsulation instead. Simply\n

Note that if you change the encapsulation,\n

will go down. If they use two different encapsulations\n

languages, they won’t be able to communicate.\n

see the encapsulation has changed to PPP.\n

Here’s the configuration I did on R1. The\n

default, so I only configured the clock rate,\n

is on R2, with no CLOCK RATE command because\nit is the DTE end.

Now you’re probably wondering, how can I\n

to show you I had to recreate this connection\n

these lectures, doesn’t handle physical,\n

display as DCE. Anyway, the command to view\n

ID. As you can see R1 is the DCE side, and\n

I used the same command on R2, and you can\n

the Tx, transmit, and Rx, receive clocks from\nR1.

So, that’s a very basic overview of serial\n

should know. The default encapsulation on\n

them to use PPP encapsulation instead with\n

the encapsulation on one side, remember to\n

connection is DCE and the other is DTE. You\n

DTE with this command: SHOW CONTROLLERS, followed\n

configure the clock rate, the speed of the\n

CLOCK RATE, followed by the clock rate in\nbits per second.

Let’s return to the OSPF point-to-point\n

IP OSPF NEIGHBOR on R2. Notice that R2 has\n

BDR, or DROTHER, a dash is displayed. This\n

doesn’t use DRs or BDRs, as I mentioned\nbefore.

Final point on this topic, you can manually\n

The command is IP OSPF NETWORK, followed by\n

type that I haven’t mentioned, that is the\n

more of a ‘sub-type’. You don’t need\n

to do a Google search if you’re curious.\n

type? For example, if two routers are directly\n

diagram below, there is no need for a DR/BDR.\n

type in this case, although you don’t have\n

all link types. For example, a serial link\n

is because serial links don’t support Layer\n

Okay here’s a chart for quick review. One\n

is that point-to-point networks use the same\n

default Hello timer is 10 seconds and the\n

have to learn this network type, but just\n

type uses a default Hello timer of 30 seconds\n

Now let’s move on to look at some requirements\n

will become OSPF neighbors without issue,\n

that can occur. I already mentioned some of\n

First requirement, the area number must match\n

We’ll use this small topology of two routers\n

OSPF is enabled on G0/0 in area 0. However,\n

IP OSPF NEIGHBOR on both devices, they have\n

I changed the network command on R2 to use\n

So, that’s the first rule. For two routers\n

the same area. But we already covered that\n

in the same subnet to become OSPF neighbors.\n

Notice that R1 and R2’s G0/0 interfaces\n

OSPF on both of the interfaces. But when I\n

I once again configured R2’s interface in\n

to edit the network command so that OSPF is\n

Next up, here’s one we haven’t covered\n

You can actually ‘shutdown’ the OSPF process\n

OSPF operation, without removing the OSPF\n

Here’s how to do it. From OSPF configuration\n

a message is displayed indicating that its\n

no neighbors are displayed in SHOW IP OSPF\n

SHUTDOWN, A message indicates the neighbor\n

That one won’t be a problem unless you manually\n

not a problem. Next requirement, the OSPF\n

Let’s see how that works. I haven’t configured\n

configured any loopback interfaces, so each\n

its router ID, 192.168.1.1 for R1 and 192.168.1.2\n

router ID, the same as R1’s. As I have shown\n

or use CLEAR IP OSPF PROCESS for the new router\n

PROCESS. Immediately the neighbor goes down\n

instead of the neighbor coming back up, this\n

router-id 192.168.1.1 from 192.168.1.1 on\n

neighbor stays down. So, let’s fix this.\n

with NO ROUTER-ID. Note that you don’t actually\n

the command. NO ROUTER-ID has the same effect\n

command. This time, without having to reset\n

to 192.168.1.2 and the neighbor comes up again.\n

I actually didn’t expect this, but I realized\n

at the time, so the router was free to change\n

So, watch out for duplicate router IDs. Next\n

match. In both of the network types we looked\n

defaults are 10 seconds and 40 seconds. But\n

The Hello and Dead timers are configured directly\n

the Hello timer. IP OSPF HELLO-INTERVAL, followed\n

Then the Dead timer. IP OSPF DEAD-INTERVAL,\n

then goes down. Note that I changed both values,\n

if you only change one the neighbor will still\n

OSPF HELLO-INTERVAL and NO IP OSPF DEAD-INTERVAL\n

Notice the method I used to return them to\n

router ID. I didn’t have to actually specify\n

20 to remove the commands. Anyway, now that\n

So, remember to check the Hello and Dead intervals\n

Next up, authentication settings must match.\n

an OSPF password, and then the router will\n

a matching OSPF password. Let’s take a look.

The OSPF password is configured directly on\n

followed by a password of ‘jeremy’. Note\n

on the interface. The password is configured,\n

So, I used IP OSPF AUTHENTICATION to enable\n

down, because R1 isn’t providing R2 a matching\n

OSPF authentication on R1 yet, so it’s not\n

fix this we could either configure the same\n

authentication from R2. I removed them from\n

Okay, there are two more things to mention.\n

interfaces must match. The IP MTU is the maximum\n

of the interface. The default is usually 1500\n

this requirement and the next one are special,\n

can become OSPF neighbors, but OSPF won’t\n

You can configure the IP MTU of an interface\n

MTU in bytes. I changed it to 1400 on R2’s\n

1500 on R1’s G0/0. I waited a minute and\n

actually remained neighbors. Then I reset\n

but no message came indicating that the neighbors\n

neighbor table again, and it was stuck in\n

a few more messages were displayed, and these\n

OSPF isn’t functioning properly. I used\n

value, and then finally R1 and R2 reached\nthe FULL state.

So, if your OSPF neighbors are having trouble\n

the MTU settings. Okay, last one. The OSPF\n

So, to demonstrate this problem I configured\n

and advertised it to R1. Then I changed the\n

R1’s G0/0 is still using the default broadcast\n

the neighbor went down, but then it went right\n

FULL in SHOW IP OSPF NEIGHBOR. So what’s\n

Here’s R1. R2 appears in the neighbor table\n

is working fine. But look at the routing table.\n

routing table, but it’s not. This is what\n

match. It can be tricky to troubleshoot because\n

like everything is working fine. Make sure\n

Okay, I’ll leave it there. There is of course\n

plenty for the CCNA. Make sure to remember\n

them as a list, but make sure that if you\n

The final topic for today’s video is LSA\n

the exam topics list, so I’m just going\n

overview of some basic LSA types. To do so,\n

modified it, adding an Internet link on R4.\n

I use DEFAULT-INFORMATION ORIGINATE to make\n

let’s talk about LSAs. As you already know,\n

in the same OSPF area share the same LSDB.\n

3 you should know for the CCNA. Those are\n

‘network LSA’. And type 5, the ‘AS external\n

First up is type 1, the router LSA. Every\n

LSA. The router LSA identifies the router\n

networks attached to the router’s OSPF-activated\n

LSA. It is generated by the DR of each ‘multi-access’\n

is an Ethernet network using the broadcast\n

which are attached to the multi-access network.\n

LSA. This type of LSA is generated by ASBRs\n

of the autonomous system, the OSPF domain.

Here’s a look at the LSDB on R1, using the\n

doesn’t actually matter which router I use\n

because all routers in the area have the same\n

a Type 1 Router LSA identifying itself. This\n

but each of these router LSAs contains information\n

to. Notice that there is only one Type 2 Network\n

subnet. Even though R1, R3, and R5 are DRs\n

are connected to the interfaces so no Type\n

Type 5 AS-External LSA is generated by R4.\n

with the other routers. Okay, that’s all\n

stated in the exam topics list, but I just\n

some of the basic LSA types you will encounter.

I told you we were going to cover OSPF in\n

these past three days we definitely did that.\n

sure you understand the material in these\n

to, and feel free to ask questions in the\n

covered in today’s video and then move on\n

types, focusing on the two you need to know\n

Because Ethernet connections are dominant\n

be using the Broadcast network type. But also\n

and the basics of serial interfaces that I\n

some requirements for OSPF neighbors and adjacencies.\n

but make sure you can identify them all and\n

the three most basic OSPF LSA types. Type\n

And Type 5, the AS-External LSA. Make sure\n

question from Boson ExSim for CCNA, my favorite\n

Which option states a characteristic of the\n

than the OSPF broadcast network type? A, DR\n

elections are not held. C, Neighbors are dynamically\n

discovered. Pause the video to think about\nyour answer.

The answer is B. In the OSPF point-to-point\n

held. C, neighbors are dynamically discovered,\n

network type, but it is also true about the\n

There is an OSPF broadcast network with 5\n

interface. How many FULL OSPF adjacencies\n

BDR. B, 2 with the DR and BDR. C, 4 with all\n

to the segment. Pause the video to think about\nyour answer.

The answer is C. The DR forms a FULL adjacency\n

segment, so C is correct. It doesn’t form\n

so B and D are incorrect. A is incorrect because\n

neighbors, not all four. Let’s go to question\n3.

Which of the following are requirements for\n

A, Hello and Dead timers must match. B, OSPF\n

must match. D, Interfaces must be in the same\n

Or F, interfaces must be in different subnets.\n

The answers are A and D. For two routers to\n

timers on their interfaces must match. They\n

here are the requirements for OSPF neighbors\n

Which of the following OSPF LSA types is generated\n

such as the broadcast network type? A, type\n

the video to think about your answer.

The answer is B, type 2. Type 2 is the ‘Network’\n

network. It lists the routers which are attached\n

the Router LSA type. D, Type 5, is the AS-External\n

in this video. It’s called the ‘Summary’\n

R1 is connected to an OSPF Broadcast network\n

segment and R3 is the BDR. All routers on\n

You issue the ip ospf priority 100 command\n

the following statements are true about the\n

two. A, R1 is the DR. B, R1 is the BDR. C,\n

isn’t high enough. D, if you issue the clear\n

the BDR. E, if you issue the clear ip ospf\n

DR. And F, the DR and BDR of the network are\n

The answers are D and F. The default OSPF\n

entering the command R1’s G0/0 interface\n

It’s still a DROther, but priority isn’t\n

give up their positions, so R1 will not become\n

and F is correct. If you issue the CLEAR IP\n

R3, will automatically become the DR, not\n

you issue that command, when R3 becomes the\n

Since R1 has the highest priority, it will\n

correct. That’s all for the quiz. Let’s\n

Okay, here's today's Boson ExSim practice\n

FASTETHERNET 0/1 command on Router1 and receive\n

the command, and here's the question. Which\n

the best answer. Okay, pause the video now.\n

Okay, let's check. So, I believe the correct\n

options and then I'll go on to D. First up,\n

Well it says right here, Router1's state is\n

connected to a point-to-multipoint network.\n

so that's incorrect. C, Router1 is configured\n

the timers here, they are the defaults. Also,\n

think there is any problem with Router1's\n

higher than 50. You can see here that Router1's\n

BDR doesn't necessarily have a priority higher\n

Router1, 50, but a higher router ID. So E\n

The key to this question is knowing the difference\n

those words are used to mean the same thing,\n

different. Look here in the output. Neighbor\n

So, although Router1 has 5 OSPF neighbors,\n

in the OSPF FULL neighbor state. This number\n

the DR and BDR, but also Router1's DROTHER\n

the 2-way state with another DROTHER. So,\n

OSPF broadcast network. And DROTHERs can only\n

2 routers. So, I chose this question because\n

between a neighbor and a full OSPF adjacency.\n

is correct. Okay, pause the video now if you\n

notice that it includes a reference to some\n

INTERFACE command. And this Cisco documentation,\n

and it's another great study resource. Okay,\n

please follow the link in the video description.\n

exams I used when studying for both my CCNA\n

once again, follow that link in the video\ndescription.

There are supplementary materials for this\n

the software ‘Anki’. There will also be\n

some hands-on practice. That will be in the\n

the link in the description, and I’ll send\n

Before finishing today’s video I want to\n

I’ve noticed an increase in the number of\n

all of you, both JCNA and JCNP-level members.\n

JCNP-level members one by one, but the list\n

list up here. Your support helps me keep making\n

I’m really grateful for your support. This\n

of recording by the way, August 23rd 2020,\n

on here don’t worry, you’ll be in future\nvideos.

Thank you for watching. Please subscribe to\n

and share the video with anyone else studying\n

check the links in the description. I'm also\n

or Basic Attention Token, tips via the Brave\n