Time
15 hours 34 minutes
Difficulty
Intermediate
CEU/CPE
20

Video Description

OSPF Lab For this lesson we create Areas with a specific group of routers and show you how to apply/configure the components required to build an area. We'll demonstrate how process ID is a factor in the "create area" process, how to calculate and apply wild card bits and the importance of Area IDs in this process. Here's a neat trick -- you'll also learn how to manually create loopback addresses and map them back to the routers within your new Area whenever OSPF selects its own router ID. And you'll learn what event has to occur before a loopback address could fail.

Video Transcription

00:04
Now we're gonna move on to our oh SPF lab,
00:07
as depicted in the diagram on the board. I'm gonna create area zero between Router one router to Router three and Router four. I'm gonna create area 51 behind Router two over here, and I'm going to create area one
00:22
behind Router one over here.
00:24
So
00:26
that's going to
00:27
router one. I'm gonna begin this time on rather one,
00:32
and I'm going to enable the SPF process on the router by saying router Oh, SPF and hit Enter.
00:39
And now again, it says it is telling me that this is an incomplete command. So I pull up the command again and execute the help feature by saying question Mark.
00:50
And now it is asking me for a process i d,
00:53
which can range between one and 65 5 35
00:58
now with the I g R. P. The number it was asking me was the autonomous system i d. The autonomous system I d is globally significant, which means every router in your network needs the same number.
01:11
So we picked 148 g. R p.
01:14
The process I d, however, is locally significant, so every router in our network. Me run
01:22
a different process, I d And those routers will talk to each other. However, that is bad practice. So we're going to stay consistent and pick 100 again
01:32
Are prompt changes to the router prompt.
01:36
And now we're ready to do our network statements, just like we have been doing for rip and the A g R P. So I'm going to say network
01:46
1 50
01:48
0.1 on one
01:49
0.45 not zero.
01:55
Next, it is asking me for a while for a wild card mask or a wild card bits.
02:00
This works the same as it did in E I g R p.
02:04
So, once again, our mask on the 1 50 network is 255255255 to 48.
02:12
If we see abstract that from 255255255
02:16
255 We get 0.0, not 0.7.
02:23
Next. If I execute the help feature, it is asking me for the area I d remember. Between router 123 and four, which is network 1 50 I'm gonna create area zero, so I simply say Area zero.
02:39
Next. I'm gonna go ahead and take care off the other side
02:44
where I'm gonna have network one. I mean, area one. So I did a network statement for this side on Router one, where Area zero exists. I'm gonna go ahead and do a network statement for this. End the link between router one and router to one,
03:01
which is going to be area one.
03:05
So let's go to Router One again
03:08
and say network
03:12
$200 202 $100 0
03:19
And my wild card is going to be 0.0 dot zero dot
03:24
three. Since my mask is 255255255
03:30
Not 252
03:31
And this is going to be area one.
03:36
Now let's execute,
03:38
assure command and see what the SPF has done so far,
03:43
we say we do the command Do show i p o S p f
03:49
and hit Enter
03:51
and you see that? Oh, SPF went ahead and picked a router. I d for itself and the router i d was picked as the 202 102 100.1 address.
04:03
Now, if I look at router ones show I'd be interface brief. Do show I p
04:11
interface
04:13
brief.
04:15
I will see that on fast. Ethernet 00 I had the address 1 51 01 45.1 Command
04:23
are 1 51 1 45.1 i p and on serial 000 I had the 200. 202 100.1 i p
04:31
Since I did not execute the router, I d command and manually pick around right d
04:36
and since nor did I have Lou back interfaces in place over here. As you see, there are no Lou back into faces on rather one.
04:45
The router went ahead and picked the highest physical I p.
04:49
So the highest I p configured on a physical interface which happened to be 202 102 101.
04:58
Now what if I want my router? I d to be to be tied into
05:03
a loop back address, which is good practice, because Lou back interfaces don't fail unless the whole router fails. I don't want
05:14
at some point serial 000 to fail and then end up taking down my whole SPF.
05:20
So
05:21
I'm gonna go ahead and create a loop back address
05:26
on router one. I'm going to say I n t
05:30
loop back zero
05:32
That brought up my lube back interface. And I'm simply going to give it an I p address of 1.1 dot 1.1
05:41
with the mask of 255255255255 for Luke back interfaces. This mask or master slashed 32 is allowed.
05:53
No.
05:54
Did the router changeover do? Sure. I p o S p f process do sh i p o S p f
06:02
Did the router change? It's Lou back. I mean, it's router I d. To the loo. Back address? No, I did not. I actually have to clear the SPF process. Bring it down. And then when it goes back up again, it hopefully will pick the 1.1 dot 1.1 address.
06:19
So do clear. I be
06:23
crew SPF
06:25
process.
06:27
And I say yes.
06:29
That takes down my process and brings it back up again. And now if I live, look at the do show I p o S P f command. My router I d has been picked as 1.1 dot 1.1 because the router prefers the highest configured Luke back
06:46
address as it's rounder I d.
06:48
Over a physical interface address.
06:53
However, it is good practice too hard called this address with the Router I D Command anyways,
07:00
so
07:01
I go back into my routing process Router. Oh, SPF 100
07:08
and I say Router dash I D or router hyphen i d 1.1 dot 1.1 and hit Enter.
07:16
It's asking me to clear the process again
07:18
because it thinks that I entered in a new router, I d. So I'll go ahead and comply with it.
07:29
The reason you want to hard, cold your your router, I d. Is because
07:33
let's say I have picked 1.1 dot 1.1 as my router i d. And then at a later date, I create another loop back address
07:43
that has the address 201 11
07:46
And then that's another later date. The router reboots because there was a power outage. When it comes back, it will come back with
07:55
the router. I d off 200.1 dot 1.1 not 1.1 dot 1.1 because it will automatically pick the highest
08:05
Lou Back i p address. But if I want to keep it at 1.1, not one, not one. I should hard code it
08:13
now. Just a little side tidbit that I want to show you. What if I pull out this router
08:22
and I go into it?
08:24
And remember, this is a brand new router. I pulled out,
08:30
let it boot up,
08:33
and I tried to start the SPF process on it. Remember, this is a brand new router. If I do the show, I mean defence brief command. They are No I p addresses assigned on it
08:46
if I try to start. Oh, SPF router. Oh, SPF 100.
08:50
It says U S P M process 100 cannot start. There must be at least one up I p interface.
08:58
So on a router without any eyepiece. Oh, SPF who refused to start? Why?
09:05
Because the first thing was be able Do is go looking for a router. I d And since it can't find itself a name,
09:13
it won't begin. It won't start the process.
09:16
Let's get rid of this router.
09:20
Okay? We're done with the outer one at this point, I'm going to go ahead and do router to
09:26
So before I even begin
09:30
the always be of process on router to I'm gonna go ahead and create a loop back in the face, Lou back zero
09:37
i p address
09:39
tue dot to dot to dot 2255255255
09:43
255
09:46
Then I'm going to begin my oh SPF process
09:50
Rato SPF 100 do my network statement for the 1 50 Network network 1 51 a 1 45
10:00
Now, this time I'm not going to pick the network address. I'm gonna pick the I P address on Router two's 00 interface
10:09
as you remember or should remember from me as your pee when you don't pick the network address
10:15
in your network statement. Instead, you picked the I. P address. You use the all zeros wild card
10:22
and this goes into area zero
10:26
and then network 10 dot Tenn 10.0.10 dollars to 54 which is the f zero slash 1.10 interface address.
10:37
And with the old zeros wild card. This I said I'm gonna put an area 51 because I think it's funny,
10:43
then Network $20.20. $20 to 54 wild card. 0.0 dot 0.0 and area 51. Again,
10:56
let's look at our
11:01
oh SPF new show I p o S p f
11:03
and you see that my router i d was automatically picked as two dot to dot to 2.0.0.2. I am, however, gonna go ahead and hard code that anyways, because that is best practice
11:16
and again asked me to clear the process. Nuclear I'd be or Thea
11:22
Process.
11:26
I will save my work
11:28
and move on to Router three.
11:33
Quickly get Router three. Done created Lou back address on router three.
11:37
So
11:39
I, Auntie Lou back
11:41
zero i p address to eat out of that tree. That 3 to 55255255255
11:48
Start the west. We have process.
11:52
Give hard code. My router I d.
11:56
As $3.3 dollars three.
11:58
Then say network
12:00
1 51 01 $45.3
12:03
and followed it up with all zeros.
12:05
Since this is the I. P address, not the network address area zero
12:13
save my work.
12:18
Go to outer four and do the same interface. Luke back
12:24
zero i p address 4444
12:28
25525525555
12:33
And then start Mato SPF process.
12:37
Do my one network statement 1 51 01 45.0 This time I am picking the network address, not the interface address on F 00 which should be 1 51 1 45 dot for I'm not using that. Instead, I'm choosing or opting to choose the network address.
12:56
Hence, my wall card is going to be 0.0 dot seven. Once again, I simply say abstracted my sub net mass, which was 255255255 to 48 from all 255 or from all 255255255255
13:15
And I get a 0.0 dot 0.7 wild card,
13:18
an area zero.
13:22
Let's go ahead
13:24
and finish up router to a one, and then we will look at our work.
13:33
So
13:37
interface Lou back zero i p address. If you want to Rwanda to a 12 a 1255255255255 I simply matched the I p addresses for the loot bag. Zero interfaces on each router
13:54
to the router number. So one was 11112 was too too, too too.
13:58
Three was 3333 and so on and so forth. Now I'm going to start my oh, SPF routing process
14:07
and execute my one network network statement, which is network 202 102 $100 0
14:15
The mask on this point to point link A CE 255255255 to 5 To subtract that from all to five fives and you get 0.0, not three. And this is going to be area one.
14:31
Save my work
14:37
and let's go
14:39
check our stuff from router one.
14:41
So I log into outer one
14:48
and execute the command shoe. I p o S p f neighbor. So we are on Router One checking our show I p o S P f neighbor command
14:58
and
15:00
router. 2222 Which is
15:03
about her i d. 2222 which is round or two
15:07
shows a priority of one,
15:11
and
15:13
it also shows that I am fully adjacent with router to
15:18
and router to is the D R
15:22
router. Three.
15:26
I am also fully adjacent with,
15:28
however, Router three is a D R. Other, which means it's not a designated router or a backup designated router.
15:35
Same with Router. Four. So where did my backup designated router ago?
15:39
Let's look at the topology from Router four or look at the neighbors from Router four.
15:45
So if I execute the show, I p o S p f neighbor command
15:52
from router four,
15:54
I find out that router one where I was sitting originally is the VD are or the backup designated router.
16:04
So in this topology, I do not want a backup designated router usually best practices that you do not let oh SPF elect a backup designated router you do not want
16:18
once the d R goes down or if the D. R goes down, you want to be informed off it. You don't want a backup designated router off a sudden picking up the roll off a designated router because the designated router for areas euro will be passing a lot of traffic. So you would have spent a lot of money on that router. If that router goes down,
16:38
you want to know about it.
16:40
You don't want no SPF to automatically elects someone else's the D R and then end up crashing that router because it cannot handle the load.
16:48
So I want Router one to be my designated router, and all other routers to be D are other routers. I do not want a BDR in my anthropology or a backup designated router in my anthropology.
17:02
Now I could go increase rather ones router priority
17:06
to something higher than one. As you see, everybody's default priority is one on area zero,
17:15
or the best practice is that I go and change route or 23 and four zo SPF priority to zero to exclude them completely
17:27
from the back of designated router and designated router election.
17:33
So
17:37
I go to Router to
17:38
and I go into interface
17:42
fast. Internet zero slash zero,
17:45
and I changed the router priority with the command I p o S P f
17:52
priority zero.
17:55
Then I cleared the process
18:00
for SPF Do try, take SPF down and when it comes back up, it'll come back up with a priority of zero.
18:10
And you see all my all my neighbors were reset.
18:15
Now
18:15
I go to Router four and do the same. I go into interface fast Ethernet 00
18:23
and say I p o S p f
18:27
or SPF priority
18:30
If I can type o s p half priority zero and do a clear i p o S P f process to reset the process. So it comes back with the priority of zero
18:44
Do the same on three
18:48
interfaced faceted at 00 i p
18:52
Oh, SPF priority zero Do clear i p o S p f
18:59
process.
19:03
And now let's go check
19:06
on router one. But before checking on router one, I also have to clear the process here. Make sure
19:21
that it becomes the designated router now by default router. Once priority was one, everybody else's priority is set to zero, which means they can't even participate in the
19:33
designated router and backup designated router election. So router one should have become the d r. Let's find out. Show I p o S p f
19:45
neighbors.
19:47
And sure enough, I see that router to is the d r. Other router four is D are other and Router three is a d r other. Also, which means I should be the d. R.
19:57
We will go check that in a minute.
20:00
And you see that router to Router three? I mean, writer for and Router three's priority has been set to zero.
20:07
Now, all of these three routers are fully adjacent with me,
20:12
which means they have exchanged the full database or link state database with me.
20:19
How about with each other?
20:22
Well, let's find out. Let's go to route or four
20:26
and execute
20:27
the show. I p o S p F neighbor Command.
20:33
You see that Router four is only fully adjacent or has exchanged its full database on Lee with the d r
20:41
with router to and router three. It is on Lee in the two way state in the neighbor change machine.
20:48
So are in the neighbor state change machine.
20:52
They're in the to a state, which means Router three has seen its own router. I d in hello set from router to
21:00
as that iterated before, you only become
21:03
fully adjacent with the D. R and the backup D r.
21:10
Since there is no backup d are you only become fully adjacent with the designated router.
21:17
Now let's go check
21:22
our routing table on router to a one.
21:29
So the routing table on router to a one show I be route
21:33
U S P f
21:37
I hit enter,
21:38
I see Network 10 network 20 and network 1 50 is available to me True Oh SPF This all the way on the left hand side designates
21:49
that this is an O SPF route
21:52
then this I a that you see
21:56
it means that this is an enter I standing for inter is standing for area All these routes are inter area routes
22:07
So
22:10
if I look at meant apology off course on router to one I'm sitting in area one These routes are coming from area zero
22:18
and area 51 So hence they are inter area routes.
22:26
Then in brackets you see the 1 10 as always
22:32
This first number
22:33
is the administrative distance
22:36
So this first number is the administrative distance for SPF which is 1 10
22:44
the 66 here
22:48
The 66 hair is your SPF metric
22:52
now Oh SPF uses
22:56
something called cost as its metric
22:59
so SPF uses cost as its metric and cost is defined as
23:06
10 to the power eight divided by
23:11
bandwidth.
23:11
It's that simple.
23:14
Tend to the power eight divided by bandwidth.
23:18
So for 100 megabyte link or 100 megabit ling
23:23
100 megabits is 100,000 killer bits
23:30
and then you add another 34 bits.
23:33
So you have a one with 12345678 zeros. If you divide that by 10 to the power eight, which is a one with eight zeros, you end up getting
23:47
one.
23:48
So the cost of our 100 megabits per second link or 1000 kill a bit per second link is one.
24:00
If we look at our show I p o S P f interface serial 010 which is the interface running.
24:07
Oh, SPF
24:10
You see
24:11
that
24:17
my cost
24:18
on a
24:21
128 K link is 64. Let me go check the cost on router ones at 00 and you will see that it stays One show i p o S P f interface
24:36
fast Internet zero size zero.
24:38
So over here, the cost say's one. So for 100 megabits per second link, the cost is one
24:47
the priority for this interface is one, and we know that is the default priority.
24:52
It also shows that my hello timer is 10 seconds. My dead interval is 40 seconds.
25:00
So the dead interval is usually set by default to four times the hello timer.
25:11
No
25:12
going back to router one.
25:15
I also want to point out
25:17
if I say show I b o SPF neighbors
25:22
on the link with router to a one.
25:26
You see, it simply says priorities, your by default. And it's his full slash hyphen
25:33
over point to point links. There is no designated router or back back up designated router. Election
25:40
doesn't make sense. There are only two routers. There's only gonna be one adjacency between them,
25:45
so it doesn't make sense to elect designated routers or backup designated routers. So from the point of view of router to a one, also, you will see that there is no d. R or BDR show I P O S P F
26:02
neighbor.
26:03
So rather to one is neighbors with router won the priority set to zero,
26:10
and there is no d. R or B d. R. I and I am fully adjacent with Router one.
26:18
Lastly,
26:21
two more things.
26:25
Let's look at our
26:27
debug i p packet
26:33
And you see that hellos are being sent itude to address to 24 005
26:41
Now, what happens
26:44
if I
26:48
What happens if I turn off the bugging and then a debug i p o s p f events? And Claire
26:57
this process clear the SPF process so clear I p West pf
27:03
Did I not turn off the bugging you space all
27:07
okay? Now I turn off debugging for debug i p o S p f events
27:15
and then I
27:17
Oh, the events. I'm going to see the Hollows. Of course. Clear i p o S p f process
27:23
and I say yes.
27:27
Now those neighbor states that you saw that I discussed earlier You can catch some of from here.
27:33
I was able to catch a few if, um so I cleared the process.
27:44
As you see, I cleared the process and then you see two way communication
27:48
and then you see X start
27:51
and did of his description packets being exchanged.
27:56
Then you see X start.
27:57
Then you see exchange
28:03
and at some point it was should say full.
28:08
So you have elected the d R and B D r
28:11
you still in X starts?
28:15
Well, we didn't get to see the full state, but at least we got to see some of the ST changes.
28:22
Oh, here we go. Full.
28:25
So when you're fully synchronised your database with
28:30
Router three withdraw variety three days without without three, it went to four. Or from loading too full.
28:37
We even got to see the loading state.
28:42
The next command we're gonna look at is
28:47
the show I p o S p f data base command.
28:52
And you see
28:55
that
28:56
this is your link State database for area zero over here. The links their database for area one starts. So let's look at the link State database for area zero.
29:07
This first stands up
29:08
is your router l Essays or your tight one l essays.
29:14
This second stanza
29:17
is your
29:18
network. Ellis is our type to el essays,
29:22
and this third stands up.
29:25
Is your type three l essays or summary l essays.
29:30
Okay, for the type one l essays. You see, each router
29:33
is the advertising router. Is each router produces one type one. L s a
29:40
okay. And the link it's advertising is the 200 link and,
29:47
well, the link it's advertising is represented in the routers Router I d.
29:52
Then you have the network link states, which is your type, too. L essays and the advertising router is the d r of that network, which is router one.
30:04
Then you also see that
30:08
the to a be ours, which is router one
30:12
and router to this 202 102 101 is rather one
30:17
and
30:18
router to are producing
30:22
your summary, Ellis is because they are the a b ours and they're injecting networks from one area into another area.
30:30
We do not see a type four or a tight five l s a in our database because we do not have external routes. That is not part of C C. N A.
30:41
The last thing I'm going to do with the SPF
30:44
is to show you how low SPF authentication works.
30:48
So we're going to authenticate area zero.
30:52
So I go into outer one
30:55
and I go into
30:56
the SPF process by seeing Roger Oh, SPF 100
31:02
and then I say area one
31:07
authentication.
31:11
Then I go to the interface facing router to one. So interface
31:17
serial 000 because area one exists between router one and router to a one. I go into this interface and I say I'd be Oh, SPF
31:30
No,
31:30
I can either do simple
31:33
text authentication, clear text authentication. Or I could do message digest authentication, which is a lot more secure.
31:42
Clear text with Indication will send my password
31:47
across the link in clear text Message Digest will encrypt my password before sending it over. Or actually, the actual password is never sent on. Lee, a hash of the password is sent.
31:57
You see that? As soon as I turned on authentication and the debt timer expired on the on the other side or on my side, the debt timer for router to a one row 21 was brought down. So the neighbor is down
32:13
because now I locally on router one, I have authentication but no authentication configured on the other side.
32:22
So on this end, I'm going to say i p o S p f
32:24
message digest key,
32:28
and I'm gonna pick a number for the key. He won
32:32
nd five the word MD five and then a password. I'm going to simply pick it to be
32:38
Cisco.
32:43
I'm gonna save my work and go do the same for router to a one.
32:53
I'm gonna go into the writing process
32:58
and say
33:00
Area one authentication message digest.
33:06
I did do that on Router One now. Deny.
33:09
Let me just make sure
33:12
you check my show. Run.
33:16
Actually, I did not do that on Roger one. Let me go ahead and change that. I did not say message digest on Router one. I just said area one with Indication, which is clear text with Indication which I don't want.
33:30
So
33:32
no area one authentication to take it away. Then area one authentication
33:40
message digest.
33:43
See if my work
33:44
go back to router to a one.
33:50
And I already have Area one authentication message digest on this end. Now, I just have to enable the authentication on my interface. So
34:00
interface serial zero slash one slash zero. The interface facing rather one.
34:07
And then I said I'd be Oh, SPF message digest. Ki won. This key has to match on both sides
34:15
MD five and the password has to match on both sides.
34:20
And pretty soon I should see
34:22
debug my i p o s P f events
34:27
and my
34:29
my
34:30
magicians. He came up Show I p O S P f
34:36
process.
34:37
So I p o S p f neighbor, I mean and rather one is up, and rather one and two are authenticating each other so that nobody else can unplug that device and plug in their own device and then get all your data.
34:52
If I say debug i p o S p f events.
35:01
See, now you're sending authentication information because now the debug
35:07
command shows that you're sending the youngest key, which is Cisco.
35:12
Turn off my debugging and this concludes, Oh, SPF.

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