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Cisco's approach to its ROUTE exam is entirely real-world, and Jeremy's video course really prepares you for the exam with GNS3 (an open-source Cisco emulator).

By the time you're done watching you'll be ready to Configure EIGRP, OSPF, and BGP at a master level; grasp the big-picture of worldwide Cisco network design; fill in plenty of “knowledge gaps” left by the CCNA on routing protocols; and confidently sit for the 642-902 exam....
Cisco's approach to its ROUTE exam is entirely real-world, and Jeremy's video course really prepares you for the exam with GNS3 (an open-source Cisco emulator).

By the time you're done watching you'll be ready to Configure EIGRP, OSPF, and BGP at a master level; grasp the big-picture of worldwide Cisco network design; fill in plenty of “knowledge gaps” left by the CCNA on routing protocols; and confidently sit for the 642-902 exam.
1. Cisco ROUTE: Cisco Certification and Getting the Most from this Course (22 min)
2. Lab Foundations: GNS3 Overview and Operation (37 min)
3. Lab Foundations: Network Design and Documentation (22 min)
4. EIGRP Routing: Concepts and Planning (29 min)
5. EIGRP Routing: Implementing Basic EIGRP (44 min)
6. EIGRP Routing: Implementing Advanced EIGRP (20 min)
7. EIGRP Routing: Implementing Advanced EIGRP, Part 2 (31 min)
8. EIGRP Routing: Best Practices and Design Options (25 min)
9. OSPF Routing: Foundation Concepts, Part 1 (42 min)
10. OSPF Routing: Foundation Concepts, Part 2 (23 min)
11. OSPF Routing: Implementing Basic OSPF (46 min)
12. OSPF Routing: Implementing OSPF over NBMA (25 min)
13. OSPF Routing: Implementing OSPF over NBMA, Part 2 (32 min)
14. OSPF Routing: Area Types and Options (33 min)
15. OSPF Routing: Area Types and Options, Part 2 (43 min)
16. IPv4 Redistribution: Controlling Routing Updates (22 min)
17. IPv4 Redistribution: Implementing Simple Redistribution (34 min)
18. IPv4 Redistribution: Implementing Advanced Redistribution (46 min)
19. BGP Routing: Foundation Concepts and Planning (23 min)
20. BGP Routing: Implementing Basic BGP (33 min)
21. BGP Routing: Implementing Basic BGP, Part 2 (33 min)
22. BGP Routing: Tuning Attributes (29 min)
23. BGP Routing: Tuning Attributes, Part 2 (49 min)
24. Path Control: Configuring Path Control (49 min)
25. IPv6 Routing: Understanding and Implementing IPv6 Addressing (35 min)
26. IPv6 Routing: Implementing IPv6 Routing and Routing Protocols (31 min)
27. IPv6 Routing: Implementing IPv6 Routing and Routing Protocols, Part 2 (31 min)
28. IPv6 Routing: Transitioning to IPv6 and Certification Review (16 min)

Cisco ROUTE: Cisco Certification and Getting the Most from this Course

Lab Foundations: GNS3 Overview and Operation

Lab Foundations: Network Design and Documentation

EIGRP Routing: Concepts and Planning

EIGRP Routing: Implementing Basic EIGRP

EIGRP Routing: Implementing Advanced EIGRP

EIGRP Routing: Implementing Advanced EIGRP, Part 2

EIGRP Routing: Best Practices and Design Options

OSPF Routing: Foundation Concepts, Part 1

OSPF Routing: Foundation Concepts, Part 2

OSPF Routing: Implementing Basic OSPF

OSPF Routing: Implementing OSPF over NBMA

OSPF Routing: Implementing OSPF over NBMA, Part 2

OSPF Routing: Area Types and Options

00:00:00

It's time for OSPF to take a huge step in the world of efficiency, as we look at our special area types and options that we have at our disposal. First thing that we'll talk about as we get into some of these special options of OSPF is the place of virtual links. You'll find out very quickly virtual links do not belong

00:00:21

in your network but maybe there if you have a potentially band-datable situation. You'll see that in just a moment. We'll then look at the special OSPF area types which is one of my favorite topics just because of the names of these area types and what they can do for you in terms of efficiency. The whole time going through

00:00:40

this, I plan on doing live demonstrations of these areas so that we can see the implementation and verification to make sure that these areas are doing what they said they should. Let's start things off by breaking the rules. That's what OSPF virtual links is all about. Now, looking at the network diagram

00:00:59

that you see on the screen, you should have one word in mind and that is, "Impossible!" You can't do that. You can't have multiple areas daisy chained away from area zero because it violates the OSPF design boundaries, which are, every single area has to be directly linked to area zero. Well, this is an exception

00:01:21

to the rule and that is what virtual links are all about. First thing I'll say about virtual links is that they are a poor design criteria. You would never design a network like this with virtual links in mind. What virtual links are therefore, are sort of

00:01:38

a band aid process. Kind of just a way to make things work until you can redesign a network. For example, maybe area zero represented the hundred routers that you had at the corporate offices in California. Area one represented about 20 different branch offices you had located in Australia. Well Australia got aggressive and

00:02:00

took over the competing Australia company and with a hostile takeover, you know merged maybe the Nabisco headquarters in Australia with the Hasbro headquarters in Australia. Now I don't even know what those two companies have in common but they acquired each other, and so for the time being you have the need to link in the Hasbro networks directly into the offices in Australia and they don't have a direct connection back to area zero. That's

00:02:32

a place where the virtual link can come into play. Now as of right now I have a configuration set up to where router four is completely immersed in area zero and it's already configured. Router three has one interface in area zero and one in area one making it an area border router and it is already configured.

00:02:50

Router two is yet un-configured, because I want to show you what exactly happens when we set this up. So I'm going to start off on router two to do a show IP protocols, verify there are no routing protocols running. A little quick show IP interface brief

00:03:06

and you can see that I have my link over from router two, I got a WAN link to router three up here and that is this guy 10.1.23.1. I also have a LAN link in area two that is 10.1.1.1 over here that we're going to get up and running. So let's set this up.

00:03:26

We are going to router OSPF one. First thing I'll do is set my router ID to 2.2.2.2, and by the way, we'll find router IDs are of the essence at this point. You'll see that in just a moment. I'm going to type in the network and we'll focus on the WAN link first 10.1.23.1 0.0.0.0 is going to be in area one. That is the WAN link going from router two up to router three, and sure enough we see the neighbor relationship form and I want you to see that as of right now everything is fine. There is no error messages happening

00:04:02

because that is a valid design. Just having router two sitting in area one has not broken any design constraints. Now I'm going to add in the LAN interface. I'm going to say network 10.1.1.1, all zeros and we'll put that in area two, which makes router two an area border router and now violates all of the OSPF design rules that we have put in place because area two is not directly connected to area zero. Now what's going to happen as that gets

00:04:37

added to the process is router, let's see, we are on router two right now, router three is going to start barking. And you can see the end of some little message coming through right there. But I'm going to just give it sometime, pause the recording right here sitting on router three for the error messages to start coming through. Well, after waiting 38.3 hours the error message never came. With some of the newer IOS versions that actually

00:05:06

will report an error whenever a virtual link is needed, meaning it will all come in and say, "Hey, router two is reporting that it's got area two and that's not allowed here." So it helps you troubleshoot. In this case, we don't see any error messages but

00:05:21

we're not going to get that route. Router two if you jump up over here had the 10.1.1.1 network over here, an Ethernet zero and that route is not showing up at router three, I'll do and show IP route. You can see nothing there and it's definitely not showing up over at router four which is receiving the inter-area route. I It's receiving the

00:05:45

WAN link between router three and router two, however it's not receiving this 10.1. network back here, this Ethernet network. So what we need to do is configure a virtual link between router three and router two. Here's the syntax to do it. First thing is you need to know that this is dependent on the router ID.

00:06:07

The name of the router. This is that one criteria I was telling you that if the router ID suddenly changes, this virtual link will break. It will no longer function correctly. The way you set it up is you go on router three, I'll start it off with router three, the one that is linking it into the backbone, and going to the router OSPF process and you type in the command virtual link, oh sorry, not virtual link, you type in area followed by the area number, and in this case we are looking at area one. Area one is acting as the virtual

00:06:44

link area, followed by the command virtual link. You can see area one virtual link question mark and it's saying, "What is the IP address or the ID? That's the one to keep in mind associated with the virtual link neighbor. This is the router ID. So I'm going to say router two's ID is 2.2.2.2. Enter. That builds the bridge over to router two to say, you

00:07:11

now have a virtual link. Now I want to mention that router three and router two are directly connected over that WAN link. But the command would be the same even if there was 20 different routers in between them. There could be, you know, router three linked up to router nine right here, that's linked to router 10, it's linked to blah, blah and you know, this link goes on and on and on. Eventually it links to router two. But the point

00:07:33

is I would type in the same command. The virtual link is formed with that neighbor. We're looking for the other ABR that is linking us to the discontiguous area, if you will. Now, we're not done yet because I have to go over to router two on this side and form the virtual link the other way. The command

00:07:54

is going to be the same, meaning I'm going to go into the router process and type in area one virtual link, but now I'm going to type in the router ID of router three. So I'm going to jump back over to router two here. Get into global configuration mode

00:08:09

followed by router OSPF one. I'll type in area one. Again the area that the virtual link belongs to, space, virtual link. and then I'm just going to type in the router ID of the neighbor, 3.3.3.3. What will happen when I hit enter on that command is a virtual link is formed between those two neighbors.

00:08:33

Now a virtual link is a tunnel. I don't know if you've had experience with tunnel interfaces, but it is a tunnel that makes router 2 believe it is directly connected to area zero. As a matter of fact in the CCIE lab, one of the things that you may be asked to do is to form virtual links without using the virtual link command. Meaning you have to resort to using tunnel interfaces

00:08:58

because they do exactly the same thing. The tunnel interface tunnels the packet through so that, router two in this case, believes it is plugged right into area zero. Now look at this. It says the process OSPF VL zero is going from loading to full when loading is done. Type in show IP OSPF neighbor, you can

00:09:18

see that the neighbors looked the same. We have that same neighbor with router three but when I typed in show IP OSPF virtual link, it shows this new point to point virtual link that is a tunnel interface. Now the tunnel interface doesn't actually show up

00:09:37

in the show IP interface brief or anything like that. It's just showing right here and this is your way of being able to check the status. Just type in this command and verify that the link is up. The only reason it would fail is if we typed in a bad router ID, or the router ID somehow changed between those two neighbors. Let's check the process over on router three. That

00:10:01

virtual link should be up. I'm going to type in show IP route, and sure enough, look at that. It has an inter-area network 10.1.1.0/24 that it now has picked up from router two. That sees Ethernet zero interface over here in area two that it wasn't picking up before because that was seen as a discontiguous network. Now,

00:10:24

we should also see that over on area, oh sorry, rather four to show IP route over here and sure enough, there it is. The route shows up as 10.1.1.0/24. it has now appeared coming from that one neighbor. So that tunnel interface is successful and router two is able to advertise its discontiguous routes over across the network. Now you can do

00:10:53

virtual links within virtual links. I'm not going to show it to you because it is really ugly, but what you could do is, let's say you had, you know, another hostile takeover that took place and then ended up with area three over here with a router connected like that. You can virtual link these routers together and then

00:11:12

virtual link rather router two and router three together. It gets very ugly and very confusing, but it is possible and allows those routes traverse over. Again, this is not a way that you would purposely design a network, but rather a band aid that helps it work until you can redesign it to link all the areas directly. Now, before we get in to the next topic, I want to

00:11:34

do a little review on the OSPF areas as in their purpose. Remember, we divide the network into areas when the SPF algorithm has begun to run too often. Updates had become too numerous because the network has grown too large. So by splitting into multiple areas,

00:11:52

we make that topology database smaller for the routers within those areas so they have to run the algorithm less often. The reason that it is because we can do summarization at this point. We can summarize at the area boundaries. As soon as we do summarization, we get those new LSA types that we've talked about in the previous video. The LSAs are the building

00:12:16

blocks of OSPF. They advertise routes. They advertise routers connected to the same switch or the same subnet, That's the LSA type two. The LSA type three and four, the summary LSAs that get generated anytime. We have an ABR that passes routes from one area to the other. Those are always marked as LSA type

00:12:36

three. LSA type four identifies the ASBR, its IP address, its location. Then the type five LSA was the LSA that the ASBR generated anytime it sent external routes into the OSPF domain. I wanted to do that review because the function of these special area types that are coming up help you to manage and filter these LSAs. Let's take a look. Behind the scenes, I went ahead and

00:13:07

built the network that you see here on the screen right now. Three different areas, five different routers. Router three being the ASBR bringing RIP routes, redistributing them into the OSPF domain, and we broke them up into multiple areas because the router was getting a little crazy. We want to manage our routing

00:13:25

tables. But let's take a look at router one. I'm going to jump into router one on the terminal and do a show IP route and you can see that router one is getting all of the inter area routes. You can see the WAN links that are coming from other areas, we've got the external routes that are being shut in from that RIP router, you can see them as the E2 routes. So even though I've implemented multiple areas, router one is still getting all of these different routes and the irony of these all is that router one's only way out of area two is router two in the first place.

00:14:03

So why on earth would I want to fill router one's routing table with all of these routing information and all these detail about the WAN links and the other areas, the RIP external routes, when router one doesn't care. I mean router one just knows to go to

00:14:18

router two to get out in the first place. It's almost as if router one is better fit for just a static default route than it is to run the full OSPF, but at the same time we are running OSPF and one of our administrative challenges has been to remove all the static routing. So we want to run OSPF but, hah, do you see

00:14:39

our dilemma? Well, that's where this concept of stub and totally stubby areas come in. I love this concept for the sure fact that I love saying those names. I'm convinced that whoever created this, they had to come from California because they were probably thinking of like, "Yeah, let's create an area. Let's call it the stub."

00:15:02

And a stub will have the criteria that it will block the type five LSAs from entering that area. But you know, we wouldn't step it up even more. Do you feel the California coming in here? And maybe we want a different kind of area that's like, totally stubby man, and that totally stubby area is going to block all the LSAs from other areas, like type three, type four and type five. Those will all be blocked from entering these areas. That's

00:15:36

my envisioning of how this process was created. So that's the two different kind of areas. It's the stub area, or what's called, the stubby area will block type five LSAs from entering. Now think back, we did the fly-by-review. Was that the type five LSA? It was the external routes. Any route that was sent in from

00:15:59

router three, will be blocked from entering a stubby area. These are piece of cake to configure. I'm going to go into my router and let's start off and see. On router two over here, the ABR, and I'm just going to type in the OSPF process. Area, and this is area two. Area two is

00:16:25

a stub, that's it. As soon as I do that, area two is now configured as a stub and the neighbor fails. Because if you remember back to the HELLO packet, one of the things that must agree in my neighbor relationships is the stub flag. It's the one that was way down on the list and I said, "Ah we'll talk about this stub later." This is where we talk about it. The stub flag has

00:16:50

to agree between neighbors so that means I have to go back to router one, go into router OSPF process which has to be done from global config mode. I'll get into the router OSPF and I'm going to type in area two stub, same command. Now as soon as I do that, we're going to see the neighbor relationship reform between router two and router one, these two router right here. Now router one,

00:17:18

I don't think reports the neighbor relationship up and down to the screen. It's the logging method I have turned off. I'm going to type-in and show IP OSPF neighbors and sure enough it has reformed to that neighbor relationship. But let's check out what's

00:17:32

different. I'm going to start over on router two and do a show IP route. Router two is the router that is connected right here to the backbone and area two. Now router two shows no change in the routing table. It's still seeing those external routes, the routes

00:17:51

that the stub area was supposed to stop. Oops, my slide got jumped there. The stub area was supposed to stop but that's okay because router two is the ABR. It has all the info from area zero and all the other areas that are being injected and all the info from area two. The point of the stub area is it's supposed to

00:18:12

filter the information from reaching the routers in the area, not the ABR. The ABR is always going to have all the info. So let's jump over to router one and see if that's really taking place. Then type in show IP route and, sure enough you can see it in action. All of the external routes

00:18:33

have disappeared from router one's routing table and been replaced by this route right here. A default route is automatically generated by the ABR that says, "Hey, I know I'm filtering the routes but you can send anything that you don't know about to me because I know all those routes still and I will be able to get you there."

00:18:56

We've effectively shrunk router one's routing table from something that looks like, let's scroll up here, right there. That was its old routing table. Something that looks like this with all the external routes all the way down to this that has just the default route here in play. Now, I know it

00:19:14

doesn't look like much, of course in lab environment because there is only three external routes coming in. But man, that can have a huge impact if you have a ton of external routes, that are being redistributed into the domain. Well, let's take a look now at the totally stubby area, over here in area one.

00:19:31

Remember, these types of areas should block everything from coming in. So, I'm going to bring up my prompt and hop on to route five. That's the router way over on the right hand side. Just to verify right now, show IP route, that it's getting all of those routes.

00:19:48

Yeah, you can see external routes are flooding the table, other areas are coming in flooding the table. We got a huge routing table here. Huh! relatively speaking. So I'm going to change this area into a totally stubby area. Now the first thing I want to mention is TSA. It's for totally stubby areas, our Cisco proprietary.

00:20:08

This is not an industry standard thing although many other vendors have implemented in their own ways. This is something that is supported only on Cisco routers. So I'm going to jump over to the ABR first, router four and go into the router process to turn this feature on. Now,

00:20:28

even though this is a Cisco proprietary feature, the only one that has to be a true Cisco device is the ABR. Router four is going to be doing the filtering, stub areas, the stubby area feature is an industry standard. So as long as router four is an industry standard capable router, and can run the stub area flag, then it can handle the totally stubby area just fine because router four is the one really the one doing all the filtering.

00:20:58

Did I say router four, I meant router five. Router five is the one that's just receiving what router four has to say. Here's the command to type in. Just one more step, area one will be a stub and we'll take it one step further and type in no summary. Stub, no summary, enter, converts that into a

00:21:21

totally stubby area. They can see router five immediately fails because the stub flag doesn't agree anymore. You can see the neighbor relationship has been reset so I'm going to come over to router five, and just to prove it to you, I'm going to OSPF and just type in, area one stub. I'm not going to turn on the

00:21:38

no summary flag, we're going to keep this one industry standard and not use the Cisco proprietary feature. That should bring the router relationship back online. There's my router, it's back online. I'm going to type in show IP route on router five. Now what should we expect to see before I hit

00:22:00

that enter key? Router four is a totally stubby area blocking type three, four and five LSAs. That is, any external route that is type five, any ASBR IP address, let's type four, and any intra area routes, that's type three, those are supposed to be the summaries from other areas. So I should see just

00:22:23

a default route. And sure enough we do. You see router five has received nothing but a default route from router four. Everything else has been removed from its routing table. Now, this was a real area, it would probably have more routers in it. We'd see

00:22:39

other routes coming from our own area but router four effectively filters everything, from router five's routing table, and its topology database. So router five should have a completely clean database. I'll do a show IP OSPF database which has very little

00:23:00

information, just saying, Hey, this is the router that's advertising your one summary route, which is our router right there. But everything else has been minimized down to nothing. Talk about savings and processor cycles. That's what the stub and totally

00:23:15

stubby areas do. Now if the stub and totally stubby areas did not convince you that some beat surfer in California created this concept, this one definitely will. It is, no joke, a not so stubby area. Again, I can see the conversation because here's what happens on the screen. You can see that area five used to be a totally stubby

00:23:41

area and the guy was like, "Oh yeah, the totally stubby area stops all LSAs..It's good." And then all of a sudden some design flaw jumps in the midst of thing, and router five gets connected to an external RIP network. And the California guy goes, "Oh, no way. Huh! Then I guess this is like a not so-stubby area.

00:24:09

Well, but it's totally stubby, so maybe it's a not so stubby totally stubby area dude." Yeah that is, I kid you not, the technical term for what area one would be. Take a look. I've got router five sitting in area one. I'll do a show IP route. You can see

00:24:29

it's still configured as a totally stubby area. I've got to get out of that voice. But it's because it is still getting the default route, all of the OSPF routes have been filtered, but the problem is its RIP ended up, or sorry, router five ended up connected to a RIP network out here. So now you have router five in area

00:24:48

one that's essentially an ASBR, right? Because it's needing to send this RIP routes to the rest of the OSPF domain but in itself, it violates the whole rule of a totally stubby area anyway. Do you see what I mean? I mean, how can you have an ASBR sitting in area one when area one is still a totally stubby area, just like it was before. Well, that's where the not so stubby area

00:25:14

comes in. What it does is it passes external routes through a type seven LSA. This LSA was engineered to kind of trick the area one. Even though area one is still a totally stubby area and it denies type three, four and five LSAs. The people that be created these areas and

00:25:36

said, "Well, I'm just denying those three LSA types and, you know, we need type four and five to really have an ASBR sitting in area one. Let's just go ahead and trick it. Let's make up some other LSA types. Let's make it type seven. And type seven LSAs will tunnel through these areas, so as router five sends those RIP routes over to router four, they come across this type seven which all the routers in that area, if there were other routers, would just say, "That's a different LSA. We're not filtering

00:26:10

that even though we're totally stubby area." Router four gets it and immediately realizes, "Aha, type seven LSAs. Those are external, so as I send them into the rest of the network, I will send them as type five LSAs." It converts them back to the original form that they were or the original form that they should be to be considered external routes.

00:26:34

So type seven, just like we saw virtual links kind of tunneled areas through each other, these LSAs types sort of tunnel through stub and totally stubby areas and that's by the way where the name comes from. A not so stubby area represents a stub, a not

00:26:50

so stubby, totally stubby area represents a totally stubby area. So here's what the config looks like. I'm going to go on router five and go into router OSPF one and the first thing I'm going to type is, this is area one. I'm going to type in area, one,

00:27:10

stub and then put a note in front of that. I'm turning off the stub capabilities because I need to convert this into a not so stubby area. The way I do it is type in area one, instead of a stub I'm going to type in NSSA. That stands for a not-so-stubby area. Just so you know I didn't make that word up. Now I have

00:27:33

to go over to router four, okay. Router four is the one, and I don't know where I am at here. Router four is the one that originally converted this into a totally stubby area. I'm going to type in no area one stub, no summary which is the totally stubby flag. I'm going to type in

00:27:53

area one NSSA, not so stubby area plus no summary. That's how we put the, oh, did I, I just need Just type in no area one stub to turn off the stub flag. There we go. Area one NSSA no summary, which now says this is a not so stubby totally stubby area and it will still be filtering those routes out. Before we do the redistribution,

00:28:23

let's go over to router five and sure enough, we should be able to see router five is, oops, ah there you go, just took a second. Router five is now receiving that default route from router four just like it was configured as a totally stubby area but now router five would be able to redistribute those RIP outs to router four and router four will receive them as those type seven LSAs. Let's do that. I'm going

00:28:51

to go into router OSPF one and again, I know we haven't talked about redistribution yet. But I'm going to type in the command redistribute RIP which sends all RIP routes in the OSPF and it just set flag of subnets, and I'm going to set the default metric of this routes to just, let's put them at ten. Now, I'll explain that whole command later on. That sends

00:29:15

the RIP routes into OSPF. Now, actually before I do that, I'm going to type in show IP OSPF database, and you can see, look at this, we have type seven external link states. Routes that are being received via RIP. Now I have some routes in here that shouldn't be there but that's just because I'm kind of simulating the RIP network behind us.

00:29:40

These are the routes that are coming in your RIP, okay. You can see all of them in the routing table, RIP routes jumping in here that are being advertised in the database as type seven LSAs. Now let's hop on over to router four to show IP OSPF database and you can see they are being received by router four. Look

00:30:02

at this, router four is receiving them as type seven LSAs as well, but it is advertising them out as type five LSAs. Now the list shrinks down here, you can see I have a bunch of type seven and it shrinks down to just one of them. The reason it shrinks down is because, as I mentioned, some of these should not be showing up in the RIP routes, they just are because I am simulating them. So it's correctly adjusting them as it's advertising them

00:30:29

out as type five. Now if I were to come up here to, let's jump over to router two. Router two should not see type seven LSAs at all. It should only see the type five because router four is doing the conversion back to type five. Type seven is only between routers and that not

00:30:50

so stubby area. So I'm going to type in show IP OSPF database, and just as expected, type five LSAs are the only thing we receive. You see the summaries, those are the type threes and fours, the router that's type two, some other summaries over here, some other router link states, which are type two, type one but overall, we can see that there are no type seven LSAs. They've all been

00:31:15

successfully converted back to the type five. Last thing I'll say on not so stubby areas is that they are usually designed goof ups. They are usually set up where you had the stub or totally stub and then oh, we have some external network that we merged into or whatever the case maybe, and we have to redistribute. So in the interim, while we were redesigning the

00:31:37

network, we'll convert it to a not so stubby area to let things work in the meantime. Last thing I mentioned in general, with the stub and totally stubby areas, is that you've now seen a major method you can use to reduce the routing tables and topology database in huge ways on the routers and these fringe areas.

00:31:58

With those design options comes one major criteria, and that is there should only be one exit point from a stub or totally stubby area. You can have multiples for redundancy, but if you do have multiple, keep in mind that you have now dual default routes that are going to be injected into a specific area, making the routing potentially inefficient. If you design it poorly,

00:32:26

meaning that you end up having load balancing happening, when load balancing shouldn't be happening because router one doesn't really have an idea of what is beyond its own area depending on the type of stub you deploy. So that's why they call them stub and totally stub is because those areas are supposed to be just a stub of the network. There's only one way in and one

00:32:48

way out of them. Now that known, let us wind things down. We started off this whole video by taking a look at Virtual Links which is essentially a band aid for the network, a way to patch the network, while you redesign it so all areas are directly connected to area zero. We then got into the special OSPF area

00:33:07

types which are for the stub, the totally stub and the not so stubby area and saw the implementation of those one by one as we walk through a live topology and saw the effects of each one of those area types on our routing tables. I hope this has been informative for you and I'd like to thank you for viewing.

OSPF Routing: Area Types and Options, Part 2

IPv4 Redistribution: Controlling Routing Updates

IPv4 Redistribution: Implementing Simple Redistribution

IPv4 Redistribution: Implementing Advanced Redistribution

BGP Routing: Foundation Concepts and Planning

BGP Routing: Implementing Basic BGP

BGP Routing: Implementing Basic BGP, Part 2

BGP Routing: Tuning Attributes

BGP Routing: Tuning Attributes, Part 2

Path Control: Configuring Path Control

IPv6 Routing: Understanding and Implementing IPv6 Addressing

IPv6 Routing: Implementing IPv6 Routing and Routing Protocols

IPv6 Routing: Implementing IPv6 Routing and Routing Protocols, Part 2

IPv6 Routing: Transitioning to IPv6 and Certification Review

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Jeremy Cioara
Nugget trainer since 2003