Tools for Route Manipulation and Control

0:04It's a wonderful thing when we have

0:05a routing domain or a group of routers,

0:07we've implemented a routing protocol,

0:09and it just works great.

0:10The best paths are being used.

0:11There's no problems.

0:12However, there are times that are

0:14going to come up in your career working in networks when

0:16the optimal path is not being taken

0:19or if you have to redistribute two different routing protocols

0:22into each other with mutual redistribution

0:24where we need some additional tools

0:25and options for controlling routing.

0:27So that's what this set of videos is all about.

0:30I want to introduce you and talk with you about some

0:32of the tools we're going to use for route manipulation,

0:34give you some examples, some hands on labs,

0:36so you can practice it, so you can be aware of the tools

0:38so that when you need them, you can both be aware

0:40of what they are, how they work, and how to verify them.

0:44And this discussion continues in the very next video.

0:46So I'll see you there in just a moment.

0:05Oh my gosh.

0:05So much fun stuff to cover.

0:07I'd like to chat with you in this video--

0:09using this topolgy that we're going to look at here in just

0:11a moment--

0:11about some of the reasons that we would use these control

0:14methods for manipulating the attitude, the brain,

0:17of a single router to make it behave in a unique way,

0:20rather than just following the defaults.

0:22So let's take a look at the topology.

0:23I'll share with you some scenarios and also

0:25a high level overview of some of the tools

0:27we could use to change the attitude of a Cisco router.

0:31So let's start with this.

0:32Let's imagine that we just threw on routing protocol

0:35A on this entire network.

0:37And let's imagine maybe it's EIGRP or OSPF.

0:41And what we're going to notice is

0:43that the goal of being able to manipulate and control

0:46the attitude of a outer is important

0:48when it doesn't behave the way we want.

0:50See, our goal is to have connectivity

0:52through the network.

0:53And we don't want any loops.

0:55For example, we wouldn't want--

0:57if we had a default route, or wanted a default route

0:59that pointed to R2.

1:00And R2 had a default route that pointed to R1.

1:01And then if either one of them got a packet

1:03and they didn't know where to send it,

1:05it would just go, "brrrrrrrrrrr"--

1:06I think that's sound it makes--

1:08until the TTL expires.

1:09Then the packet would be killed.

1:11That's not ideal to have a routing loop like that

1:14based on static routes.

1:15So with all those static routes present, if we just had a OSPF,

1:18we might think, well, it's going be great.

1:19Well, OSPF, by default, has an auto-cost reference bandwith

1:23of 100, which means it sees a fast Ethernet

1:26interface as a cost of 1.

1:27And it sees a gigabit interface as a cost of 1.

1:29So, just right out of the gate, we'd

1:31want to do some tuning for the OSPF processes, that's

1:34what we're using, and specify that we

1:35want the auto-cost reference bandwidth certainly

1:38higher than 100, maybe 1,000.

1:39Or if we have, you know, faster links than gig,

1:41we'd also want to make it even bigger

1:43and do that across the board.

1:44But once we have the basic elements in place,

1:47it should be great.

1:48It should be able to identify the best paths to the network.

1:51So as part of the EnCore and this NRC training,

1:54we've taken a look at the individual routing protocols

1:57and how they operate and their metrics.

1:58And that's important, I would say, extremely important.

2:01Before we start manipulating routes and controlling routes,

2:05we'd want to understand how the routing protocols work first

2:07before we try to change their behavior.

2:09So with EIGRP, it's bandwidth and delay, baby.

2:12That's all they-- it's the lowest bandwidth

2:14in the path, which is passed on by the neighbor,

2:17and the sum of the delays.

2:18And that's what they're basing their metric on.

2:20With OSPF, it's cost and using the linked state database.

2:24And it's important to send the defaults of how those protocols

2:26work and their AD's before we start manipulating them.

2:29Because check this out.

2:30As we go back to this drawing, let's imagine

2:32we put EIGRP on this network.

2:33And then we said, wow, if we look at the loopback

2:37here on R1.

2:38So if we look at the path from R8 to R1,

2:42the worst link in the path is going to be these serials.

2:46So R8 from all three interfaces is going

2:49to have the lowest bandwidth.

2:50And the path being those serial links

2:51because that's what's passed on with the EIGRP.

2:53That's how it works.

2:54And then the sum of the delays would

2:56depend on what the delays were advertised.

2:59So if we went to R8--

3:00in fact, let's do this as an exercise.

3:02If we went to R8 and looked at the routing to get to R1,

3:05which path should it use?

3:06Did it use this guy over here, serial 3/1, 3/2, or 4/1?

3:12And the best way to ask it, or the best way to find out,

3:15is just ask it.

3:15Let's do that.

3:16And I just realized I don't have a routing protocol running.

3:19Real quick, let's just do a router EIGRP 2, that's fine.

3:23And we'll do a network 0.0.0.0.

3:26And we are off to the races.

3:27I'll copy that and just plug that

3:30into each of these routers.

3:31One of things I love about EIGRP is-- oh my gosh,

3:33how fast is it?

3:34It is so fast.

3:36So by the time I can even paste these in on R8,

3:39if we do a show IP route for 1.1.1.1.

3:43Yeah, it's got equal cost paths routing to 1.1.1.1 that fast.

3:47So if we were to look at this and say,

3:49wow, your next hop is dot 7 and dot 6.

3:52Your traffic share count is 1.

3:54Let's do a show IP route.

3:56Yeah, we have two routes to the 1.1.1.1 network.

3:58And we might look at the topology

4:00and say, well, you know, what's up with that?

4:06Why isn't it-- if the lowest cost in the path

4:08is the serial links, how come it's not using this right here?

4:12And so it'd be important to first,

4:13before we start manipulating routes,

4:15to understand why it's doing what it's doing.

4:17So in EIGRP and the OSPF content in EnCORE and here in NRC,

4:22we've taken a look at the routing metrics

4:24and how decisions are made and so forth.

4:25And we'd want to first of all understand

4:27what it's doing before we start to manipulate it.

4:29So here are some tools that we could use to manipulate it.

4:32We could go ahead and say, I want to modify the AD,

4:35the administrative distance.

4:36We can specify using the tools of manipulation

4:39on a router, hey, if you learn about this route

4:42off this interface from this neighbor,

4:44go ahead and specify the route for just this set of networks

4:48to a lower AD.

4:49And if you do it, those will be put in the routing table.

4:52AD wins always.

4:54So that's one way to get those specific routes

4:56in the routing table to change its mind from the defaults.

4:59We could also modify the metric.

5:01Now, depending on what routing protocol we're using,

5:04it might be cost.

5:05So if it's BGP it would be the attributes, including

5:08the AS path attribute and the weights

5:11and so forth that are involved with the metric for BGP.

5:14But it's important to understand what the basics are

5:16for individual routing protocols like OSPF and EIGRP and BGP.

5:20So that if we want to, we can modify those.

5:22Now, what are some tools that we can use to modify those?

5:26And one of the main tools is called a route map.

5:31And with a route map, we can specify, OK,

5:33based on this happening, if this matches

5:36this network, that network, the other network,

5:38I want to go ahead and change, for example,

5:40the administrative distance, or the metric.

5:43And route maps can be applied for incoming routes

5:46that we're learning or routes that we're sending.

5:48It's basically a Swiss Army knife

5:49of setting the parameters.

5:51We could also set a tag.

5:52And you might say, well, Keith, why would we ever set

5:54a tag associated with a route?

5:57Check this out.

5:58Let's imagine that right here.

6:03Let's imagine that this is routing protocol A.

6:06And I'll use a different color.

6:08And we have another network, another group of networks,

6:12that are in routing protocol B. Now, this is not a design goal.

6:17Sometimes we have multiple routing protocols

6:19because we have to.

6:20We're using legacy gear or maybe we're running OSPF

6:23and we have some stuff that's still running EIGRP

6:25that we want to work.

6:26The secret is here that this network right here, network 12,

6:30which is the link 10.0.12 between R1 and R2,

6:33if we want that network to be seen by routers down here

6:38and be able to reach it, either these guys need default

6:40routes-- that works--

6:41or they need to have that information.

6:43So what we could do is we could redistribute.

6:45And that brings a whole world of challenges

6:48because the metrics--

6:49let's imagine this is routing protocol B. The metrics

6:53for routing protocol A, whether it's OSPF or EIGRP or ISIS,

6:57they are different than the metrics used

6:59by routing protocol B. And so when we do redistribution,

7:02we do it on a router that is connected

7:03to both routing domains.

7:05And we simply give the instructions,

7:06please redistribute this routing protocol B into A.

7:09And then we are also going to have the opportunity

7:12at that moment to specify the metrics and the details

7:16for those routes as they come in.

7:17Because check this out, we want fault tolerance-- usually,

7:21companies do.

7:22And so if we have R3 doing mutual redistribution.

7:25And we have R4 doing mutual redistribution from B to A

7:29and from A to B. That's fine, you might think.

7:32But what if this network, the 12 network, gets--

7:35I'll put this in a different color so we can see it.

7:37Let's imagine the 12 network gets redistributed into routing

7:40protocol B. And then R4 takes that route, the 12 network,

7:45which is in routing protocol B, and redistributes it

7:47into routing protocol A. What's going to happen then?

7:50We're going to have flaps.

7:52If that route is advertised here, then there, then here,

7:54then there, then here, then there, it shows up,

7:56it disappears, that route could be flapping, which is terrible.

8:00And that's when we'd want to use a lot of our controls to make

8:03sure that doesn't happen.

8:03One of those options is tagging it.

8:05Now, there are several options we could

8:06use to solve this problem.

8:08But one is tagging it, where we take

8:10that 12 network when it comes in, we tag it with a number,

8:12like, 777, Vegas.

8:15So we tag it.

8:16And then that route, as it lives here at the 12 network,

8:19we can train R4, hey, listen, when you're

8:21doing your redistribution, we could combine that

8:24with a route map that's looking for that tag.

8:27And we could tell R4, hey, if it has a tag of 777,

8:30don't bother bringing it in.

8:32So in combination with route maps, and also some other tools

8:35we have, we have a large assortment of lists.

8:38You might say, Keith, what do you mean lists?

8:40We've got ACL's, access controls lists,

8:42which we're not using for, like, filtering traffic

8:44at an interface.

8:45But we could use it as part of a route map to identify networks.

8:49And we can also, with some protocols,

8:51identify a network prefix and who sent it to us.

8:55And use that as part of our identification process.

8:57We also have distribute lists as part of our tool belt.

9:00And we have prefix lists, which are another amazing tool

9:03to help identify specific routes that we

9:05want to either permit or tag or filter or process differently.

9:10Another option is an offset list.

9:12And some of these do apply based on the routing protocol

9:14you're using.

9:15But an offset list, if we had, like, EIGRP or RIP,

9:19we could go ahead and apply an offset list.

9:21And we could tell R8, listen, when

9:22you're learning about the route from R7, about the 1.1.1.1

9:25network and it comes in here, go ahead and bump that up

9:28with a higher metric, an offset of,

9:30like, 50 higher than what it normally should be.

9:33And that way we're influencing the mind

9:35of R8 regarding that route by using manipulation on R8.

9:40So there are a lot of options for manipulating routes.

9:42Some of them depend on which routing protocol we're using.

9:45And there are three basic things that I want you to take away

9:47from this video.

9:48Number one, it's important to first learn

9:50the defaults and behaviors of the individual routing

9:52protocols.

9:52That's why we have so much content regarding that,

9:55regarding EIGRP and OSPF and BGP,

9:57so you can make sure you understand

9:59those defaults first.

10:00And then based on the routing protocol or protocols

10:03we're working with, we can then, if we

10:05need to, manipulate inbound and outbound route updates--

10:08modify the distance or the metrics of the cost

10:11and so forth on those routes that will effectively

10:14manipulate the behavior of a router regarding those routes

10:17it receives to prefer or not prefer one route or one path

10:20over another.

10:21So here's what we're going to do.

10:22In the upcoming videos and labs, I

10:24will walk you through a few scenarios

10:26to give you hands-on practice.

10:28So you'll have a first-hand opportunity

10:30to practice with route maps and prefix lists

10:33and distribute lists and offset lists

10:35and manipulating AD and using route maps.

10:37So you can have a taste of what it feels like

10:39and then get that hands-on practice to help reinforce it.

10:41So all that's coming up as we continue these videos together.

10:44So stay tuned.

10:44And I'll see you in the very next video.

10:46Meanwhile, I hope this has been informative for you.

10:49And I'd like to thank you for viewing.

0:05One of the best ways of learning about a tool or a method

0:07for manipulating routing is to actually do it.

0:09So in this video and hands-on lab,

0:11I encourage you to click on the link for the Virtual Lab

0:13and join me as we take a look at using distribute lists

0:17and prefix lists to change the attitude

0:19and behavior of a Cisco router.

0:22And here's our game plan.

0:23Let's implement EIGRP on all these devices.

0:26And what we'll discover is that for the 10.0.1 network

0:30and some other 10.0 networks up here, and also the 1.1.1.1,

0:34R8 is going to have two equal cost paths, one going

0:36this way, one going that way.

0:38We can verify that in the lab.

0:39And what I'd like to do to manipulate R8's behavior

0:43is change the way R7 is advertising over to R8.

0:46What we can do is, we can use what's

0:48called a distribute list.

0:51And a distribute list, as used as part of EIGRP

0:54is something to say, oh, don't bother

0:55sending him this information or advertising this information.

0:58So we can say, hey, regarding the networks of 10.0,

1:01anything, if they're 24-bits long,

1:03go ahead and don't bother advertising them.

1:05So if R7 doesn't advertise that and doesn't advertise 1.1.1.1,

1:09which we can also control, if it doesn't advertise those to R8,

1:12R8 is no longer going to have that route.

1:14And it will stop using it.

1:16So in conjunction with the distribute list,

1:18we can use an ACL to identify the networks that we don't

1:21want to advertise via EIGRP.

1:24We could also use something called a prefix

1:26list, which can also be used.

1:28And it's a little more granular.

1:29So lists in our example and our walk-through,

1:31let's use a distribute list that calls upon a prefix list that

1:35is matching on 10.0.1.anything and also matching on that

1:39specific route, and restricting those routes from being

1:42advertised to any neighbors.

1:43And then I'll walk you through it step by step.

1:45So here's our lab environment.

1:47And I'm just going to bring up Notepad for a moment

1:49because part of our exercise here is

1:51to make sure EIGRP is running.

1:52And it is not at the moment.

1:54So we do a show IP protocols.

1:56It's got no dynamic routing protocols.

1:57So let's bring up a fresh Notepad document.

2:00And we'll do a config T and a router

2:03EIGRP We use autonomous system number one.

2:05If you want to use named EIGRP feel free as well.

2:08And then we'll do a network of everything.

2:10Great.

2:10So we'll do a Control A and a Control C to copy all that.

2:14And then I'll just do a right click on each of these devices

2:17and paste it in.

2:17EIGRP is so stinking fast.

2:19Oh my gosh.

2:20We do a show IP route for EIGRP learned routes.

2:22Boom.

2:23It's done.

2:24It's very, very fast.

2:25So the two routes I want to just pay attention to here

2:28would be these guys right here.

2:30So first of all, 1.1.1.1 it has a next hop of dot 7

2:32and dot 6, which we look at our topology, that

2:35would be R7 and R6.

2:38And if we go back to the CLI.

2:41And we look at the network 10.0.1.1,

2:43it's got a next hop of 6 and 7 as well.

2:45And what we're going to do is I want

2:47to make those routes coming from R7 not look as good.

2:50And one way of doing that is by simply telling R7,

2:53don't advertise those routes.

2:54And that will give us an example of practicing

2:57with both distribute lists in EIGRP

2:59and also with prefix lists.

3:01So let's do this.

3:03Let's go ahead into R7, get on the right router.

3:05And we'll do a show IP prefix lists just

3:09to make sure I don't have any in place.

3:11And let's create some.

3:12We'll get to configuration mode IP prefix list,

3:16and a question mark.

3:18So let's call this OURLIST.

3:20And then you can give him a sequence number.

3:21Now, if you don't give it a sequence number,

3:23it'll automatically sequence them for you.

3:25But if you want it nice and tight,

3:26and you want to know what the numbers are,

3:27you can just put them in manually.

3:29I'm going to call this sequence-- you know what?

3:31What the heck.

3:32I'll live on the edge.

3:33I think it's going to start with sequence number 5.

3:35And that's going to be fine with me.

3:36So let's specify deny.

3:37And you might say, Keith, what is

3:39this prefix it's going to deny?

3:41We don't-- we're going to use this prefix list as part

3:43of the EIGRP with a distribute list option.

3:46So let's go ahead and deny 1.1.1.1,

3:49which is a 32-bit route.

3:50I need to check on that real quick.

3:52But back to R8, it is indeed a 32-bit route right there.

3:57So if we just pressed Enter right here, boom.

3:59This prefix list, if called upon,

4:01is going to deny the exact 32-bit route of 1.1.1.1.

4:06Boom.

4:07All right.

4:08Next, let's go ahead and deny something else.

4:10Do an IP prefix list.

4:12And we'll call this OURLIST.

4:13And, again, in the background, this

4:15is automatically sequencing them for us.

4:18So we'll do a deny.

4:19And let's do a 10-- you know, let's do this.

4:22Let's come up with a plan together.

4:24Let's imagine that we want to have R7 not advertise

4:3110.0.anything if it's a 24-bit mask, a 24-bit route.

4:42Now, to do that, prefix lists rock because we can specify not

4:47only that these two octets here can be wildcards,

4:49it doesn't matter what's there, but we also have the ability

4:52with a prefix list to say exactly the length

4:54of the network or prefix that we're looking for.

4:57Let me show you how to do that.

4:58This is really cool.

4:59Let's go back to our CLI.

5:00And at the CLI we'll do a deny 10.0.0.0.

5:05And then we can say slash 16, like that.

5:08And then if we add on, if we add on a GE or an LE, which

5:12is greater than or equal to, or less than or equal to,

5:16it then says OK.

5:17There's more conditions that apply.

5:18So it has to be 10.0 and, we could say, needs be less than

5:23or equal to a 24-bit route.

5:27And press Enter.

5:28And so what that would do, that would say, OK,

5:30only 24-bit routes that have the first two octets of 10.0.

5:34But any time we see the LE or GE after it,

5:37think of the slash 16 or the slash 24, whatever is there,

5:40just think of that as everything after that part of the mask

5:43is a wild card.

5:44And that we're looking for the links.

5:46We could also, if we wanted to add on to that,

5:48we could also do something like this.

5:49We could say, let's say that 10.2, let's

5:53say that anything that starts with 10.2.

5:55But it has to be greater than or equal to--

5:57let's imagine, how about 19 bits--

6:01and then less than or equal to 31 bits.

6:04Press Enter.

6:05So we can be very granular if we have a certain quantity.

6:08So this means 10.2.anything, if the mask or the length

6:13of the network is between 19 and 31 inclusively.

6:17That's what this says.

6:18So if we do a do show IP prefix list.

6:21Let's see what we have so far.

6:23We've got three deny statements.

6:25Well, just like an access control list,

6:27if we don't have some permits in here,

6:29there's not going to be a whole bunch being allowed.

6:31So let's add one more sequence.

6:33And we'll do it IP prefix OURLIST.

6:35And we'll say permit.

6:37And here's how we do the wild card that means let everything.

6:40It is 0.0.0.0/0.

6:43But we're not going to press Enter there.

6:46And then we're going to add-- this is important

6:48for the everything-- is that we're

6:49going to do a less than or equal to 32,

6:52which basically means any IP address that wasn't matched

6:54earlier is going to match here.

6:56And in this case it's a permit.

6:57So what we could do now is we could go to R7

7:00and tell R7 in its routing protocol

7:02to go ahead and apply this as an outbound distribute list.

7:06And it will not advertise, if you take a look at this,

7:09it won't advertise 1.1.1.1.

7:10It won't advertise 10.0.anything if it has a mask exactly equal

7:14to 24.

7:15And it won't advertise 10.2.anything if it has a mask

7:19between 19 and 31.

7:21So those are the three categories

7:23of routes it will no longer advertise.

7:25And then the last line here says permit

7:27everything else, which means advertise everything else.

7:30So let's go ahead and apply this by going

7:32into router configuration mode.

7:33So do show IP protocols.

7:35Just remember what routing protocols I have.

7:38OK.

7:38It's EIGRP 1.

7:39So we go to router EIGRP 1.

7:43And then we'll do a distribute list.

7:44And there's a whole bunch of things to start with dist.

7:47So D-I-S-T-R. Great.

7:49Distribute list.

7:49And then we'll go ahead and-- this

7:51is where we could call on an access list

7:53to match on what we want to permit or deny out.

7:56Or we could use the word "prefix".

7:58There's also the keyword for route map

8:00if you wanted to call on a route map.

8:02So this time we created the prefix list.

8:04Now let's call on the prefix list

8:05by using the keyword "prefix".

8:07And then we'll call OURLIST.

8:09And then a question mark, and then we'll specify "out".

8:11Now before we press Enter, let's go to R8.

8:14So a moment ago, if we do a show IP route for EIGRP

8:18learned routes or the-- let me press Enter again.

8:26So for the 10.0.1 we are going to 7 and 6.

8:29And also for the 1.1.1.1 we are going to 7 and 6.

8:33And basically R7 is going to stop advertising that.

8:36And as a result, we're no longer going

8:37to use R7 as the next hop.

8:39Let's go back to R7 We'll press Enter.

8:43We'll do a show run section router just

8:46to verify what we did.

8:48And survey says, all right.

8:50Pretty straightforward, distribute

8:51list, prefix, the name of our prefix list, out.

8:54And let's go take a look at R8.

8:56And here on R8, we'll do an Up arrow key show IP route EIGRP.

9:00And check it out.

9:01We no longer have two routes to 1.1.1.1.

9:04And that's because R7 is no longer advertising that

9:07based on the prefix list.

9:08Also, if we had the route for 10.0.1, which we also had

9:12R7 as the next hop for.

9:14And we no longer have it there, either.

9:16But what we do have, I'm just looking for dot 7

9:18as the next hop, he is advertising to us the 10.1.5

9:22and the 10.1.35 and the 10.1.7.

9:25So we're still learning routes, except he is not

9:27advertising the routes that we told it not

9:29to based on the distribute list, which was associated

9:32with the prefix list.

9:35So thanks for joining me in this lab

9:36on implementing some filtering of routes

9:38for outbound advertising with EIGRP using

9:41distribute lists in combination with prefix lists.

9:43And I'll see you in the next video.

9:45Meanwhile, I hope this has been informative for you.

9:47And I'd like to thank you for viewing.

0:05If we had a pet, we'll use a dog because it's

0:07more applicable to a dog than the cat.

0:09If we had a dog, when would be the best time

0:11to train that dog on how to behave?

0:14And the answer is as soon as possible--

0:16when it's young, when it is fresh, when it's new.

0:18Well, we have the same opportunity with routing

0:20and with route control when we do redistribution from one

0:24routing protocol to another.

0:25That's the perfect time where we can implement some controls

0:28and tweaking to make those routes behave the way we want.

0:31So let me share with you the topology.

0:33And then some ideas regarding redistribution and some

0:36controls we can put in place at the point of redistribution.

0:40So with this topology, let's imagine

0:41that we have this part of our network using all one common

0:45routing protocol.

0:46We'll call it, let's call it OSPF.

0:48That way we can put some teeth on it, as opposed

0:50to routing protocol A.

0:51And then down below, down here, let's

0:54go ahead and have all these guys run, let's pick, EIGRP.

1:01All right.

1:02So first of all, this is not a great design.

1:05However, if we had OSPF domain and the EIGRP domain

1:09that we want to share the routes,

1:10one of the key tricks I use is make

1:12sure we're focusing on one route at a time, or one network.

1:14So let's say, for example, this 12 network

1:17up here between R1 and R2, if we want reachability on here

1:21and this is EIGRP domain, they're

1:22going to need either a default route

1:24or they're going to need to learn that route,

1:26and vice versa.

1:26If we want the 78 network to be learned by router 1 or router

1:292, but you're not running EIGRP, we've

1:31got to somehow either give them default routes

1:33or give them that information by redistributing EIGRP into OSPF.

1:38So as far as manipulation and control, check this out.

1:41When we do the redistribution of OSPF, the way we do it is we

1:45go into router configuration mode for EIGRP.

1:48And then we'd say redistribute OSPF into EIGRP.

1:52Now, the problem, the problem is that the metrics

1:54are all wacky doodle different.

1:56OSPF uses costs and EIGRP uses the composite metric

2:01with bandwidth and delay being the two major factors.

2:03So how do we deal with that?

2:05Well, when we bring in a route when we do the redistribution

2:08on this guy, R3, we're going to specify what

2:11we want that seed metric to be.

2:13We can set a default or we can do it

2:15at the point of redistribution with a command.

2:17We can say, OK, any new routes that are coming in

2:19as far as manipulation and control,

2:20we want them to have a bandwidth of XYZ.

2:24And we want the delay to be XYZ.

2:26So we can make the route look as good or as bad

2:28as we want based on that redistribution into EIGRP.

2:33Then once they're there, they're going to show up as external.

2:36So that's what an external EIGRP route is.

2:39It is redistributed in from another source of static routes

2:42or another routing protocol.

2:43And so external routes in EIGRP have an administrative distance

2:47of 170.

2:49So they're not going to be preferred compared

2:52to the non-external routes with EIGRP which have an AD of 90.

2:59So just right there, if these routers have to choose a route,

3:02they're going to go ahead and choose

3:03the route with an AD of 90 if there's duplicates in place.

3:06So by default some of the defaults are going to help us.

3:08Now, the other element is, if we wanted to redistribute EIGRP

3:11into OSPF, we could do it also right

3:13here-- which is not a bad idea-- on the same router.

3:15That's going to help prevent loops.

3:17And then as we bring EIGRP routes in,

3:19we have some choices.

3:21They are going to be external routes in OSPF

3:23once we redistribute them in, including the 78 network.

3:26But we can specify, do we want it

3:28to be a type 1, external type 1 where the metric can

3:31grow and grow and grow as that route gets propagated in OSPF,

3:34or do we want it to be an external type 2?

3:37Type 2, I'm fixed.

3:38My metric is fixed.

3:39That's all I do.

3:40So inside of OSPF, we can control that.

3:42And also what we can do is when we bring routes back and forth,

3:46we can also tag them.

3:47And you might say, Keith, what's the benefit of a tag?

3:50Tags are helpful in the condition

3:53where we, if we're doing redistribution over here--

3:56this is just an example-- on R4 of EIGRP into OSPF and OSPF

4:01into EIGRP for fault tolerance-- we

4:03have two routers that are behaving

4:04that way-- we could, on the redistribution,

4:07we could tell the routers, hey, listen.

4:09Any external EIGRP routes, don't bother bringing in.

4:13I mean, they're already external.

4:14So that's a very elegant way of controlling the device

4:18and saying, you know what?

4:19These are external routes, like, the 12 network

4:22as an external in EIGRP.

4:24Don't bother bringing it in.

4:25That's great.

4:26We might have other scenarios, though, where

4:28if we tag them, if we, on R3, if we tagged all the routes

4:31as they came in and we added a tag of, let's say, 999.

4:35Just a number.

4:36So R3 tags 999 as he brings him in,

4:38R4 tags 999 as he brings him in.

4:40Then we could tell the routers, hey, listen.

4:43If it has a tag of 999, that route,

4:45don't bother bringing it in.

4:47We can control that with route maps.

4:49So we can tag using route maps.

4:51Some routing protocols allow us to tag directly.

4:53We'll do that in the next lab.

4:55And we also, when we redistribute,

4:56we can refer to a route map that's looking for a tag of 999

5:00and saying, not going to bring it in.

5:02Now, the great news is this.

5:04The great news is this.

5:05We have a lot of tools and options

5:07when we're doing redistribution.

5:08And here's one of the key elements

5:10that I learned a long, long time ago in a network far away,

5:14is that we want to avoid, which is

5:16another way of saying don't, don't

5:19redistribute a route that was sourced

5:21from one routing domain, like, OSPF at the 12 network.

5:25Don't redistribute that same route back into OSPF.

5:29So in some, like, a CCIE environment where they have,

5:32this domain and that domain, the key

5:35is just make sure that a route that was sourced in OSPF,

5:38or we'll call this routing protocol 1, routing protocol 1.

5:44And we'll call EIGRP routing protocol number 2.

5:47Make sure that any routes that were sourced originally

5:50from routing protocol 1 and then they're redistributed

5:53into a different routing protocol 2,

5:55make sure we're never going to redistribute those back

5:57in to the original routing domain

5:59because that is what's going to lead to loops.

6:02So EIGRP and OSPF have so many defense mechanisms in place.

6:06For example, OSPF, if it has the same route

6:09that it's learned via an intra-area route

6:12versus an inter-area route, it's going to choose the intra.

6:15So that's going to be chosen regardless of metric.

6:18And if it has an external type 1 and an external type 2,

6:22it's going to choose the external type

6:231 every day over the external type

6:252 because that's how it's built. So in these two scenarios,

6:29it's actually pretty tough to have a routing loop because

6:33of the defaults with the AD's and the preference

6:36for these routing protocols that they use by default.

6:39So the crux of this video is if we're taking routes from one

6:42routing domain and putting them into another,

6:44we have lots of controls at that point of redistribution

6:46regarding tagging, manipulating, which rails to bring in,

6:49which routes to not bring in.

6:51We can include tags as part of that mix

6:53as we manipulate and control the routes that are brought in.

6:56Now, some of you might be thinking, well, Keith,

6:58this would be a lot easier if we just

7:00ran OSPF in this whole domain.

7:01I know.

7:02I know.

7:02But the goal of this video, these sets of videos,

7:05is to share with you some of the techniques and tools that we

7:08can use to control the routes in these kind of corner

7:12situations.

7:13So here's what we get to do.

7:14In the next video and lab, I'm going

7:16to walk you through setting up a mixed domain

7:19environment with EIGRP and OSPF based on what we just

7:21looked at, and give you a chance to practice, first

7:23of all, the redistribution between the two

7:25different routing protocols, and have some fun with it

7:28as we can manipulate the metrics any way

7:30we want to when we do that redistribution.

7:33So I'll see you in that next hands-on lab

7:34in just a few moments.

7:35Meanwhile, I hope this has been informative for you.

7:38And I'd like to thank you for viewing.

0:05One of the best ways to learn and troubleshoot redistribution

0:07is to actually implement it.

0:09And that's what we're going to do in this video and lab right

0:11now.

0:11So click on the link for the virtual lab, and let's go ahead

0:13and do this together.

0:14Let's start by taking a look at the topology

0:16and setting up a plan.

0:18So here's our proposed plan.

0:19I propose that we take these networks right here,

0:23and we put them in OSPF area 0.

0:27Now, one thing I did, which was very convenient for this lab,

0:31is that all these networks that I've just outlined here,

0:34they start with 10.0.

0:37So we can do a 10.0 with a wildcard mask for area 0

0:40on all these routers, and they are good to go.

0:42And then, what we can do is, let's make this action down

0:45here, let's go ahead and do EIGRP.

0:48And this will give you some practice in implementing

0:50those protocols as well.

0:51This will be EIGRP, and let's use Autonomous System 1.

0:56So OSPF process id 1 we'll use up here, and EIGRP1 down here.

1:00And down here, we have these networks on the left-hand side

1:03are all 10.1-something.

1:06Over here on the right-hand side, they're 10.2.

1:08It is playground, which is really what it is.

1:10Let me go ahead and walk you through implementing this.

1:12You can follow step-by-step.

1:14And then once we have the OSPF and EIGRP implemented,

1:17we'll do a redistribution plan between those two

1:19routing domains on either R3, R4, or both.

1:23So let's implement the basic routing protocols first.

1:26All right, so I'm going to bring up a fresh notepad document.

1:28And let's do a config t, router ospf 1, and network everything,

1:34and area 0.

1:35And we'll put this on R1 and R2.

1:36Let's include all their interfaces.

1:39And that'll be for R1 and R2, all right?

1:42Boom, Ctrl-C, and R1, R2, and not R3,

1:47because R3 and R4 are going to be on the edge.

1:49So we only got some of their interfaces.

1:51So for R3, let's do this.

1:53We'll go back to our notepad document,

1:55and we'll do a network 10.0.

2:00And then, with the wildcard mask,

2:02saying that we care about the first two octets.

2:04So 0.0-- all right, that looks good.

2:07And that will be on routers 3 and routers 4.

2:11So we'll do a copy, and on router 3, we'll paste that.

2:14On 4, we'll paste that.

2:16And let's also verify we got that right.

2:18So let's take a look at our topology.

2:20So R4, it should have gig 2/0 and fa 4/1,

2:24but it should not have Serial3/1,

2:26because these are the 10.1 network down here

2:29off to the bottom right.

2:30Let's go verify that.

2:31I'll do a show ip ospf interface brief.

2:34Survey says-- great, those are the interfaces we expected.

2:37And it's going to form some neighborships here with both R3

2:40and R2 here in a moment.

2:42Great, let's go on to our config for the EIGRP portion.

2:45So config t, router eigrp, and we're using--

2:48telling the system 1, and we'll do a network--

2:51let's make it 10.1.0.0.

2:54And that's going to be the left-hand side of our network.

2:56And we'll do a wildcard mask of the first two octets,

3:00and then, also, network 10.2.0.0.

3:06And that will be the right-hand side of our network.

3:08And that will be appropriate for R3 and R4.

3:11So let's do that, just on those two routers.

3:16So here's R3, and here's R4.

3:20If we look at our topology, what that just did,

3:22that's going to pick up the fa 4/1 on R3

3:26and also these Serial3/1 on R4.

3:28and we can verify that by going back to the CLI

3:32and doing a show ip eigrp interface.

3:36And over on R3, if we use that same command.

3:39Now, let's go ahead and do routers 5 through 8.

3:42And for that, we can just do router eigrp

3:45and network everything.

3:47And that would be good for them.

3:49They can include everything.

3:50So I will copy that, and we'll put that on routers 5, 6, 7, 8.

3:53So copy, and routers 5, 6, 7, and 8.

3:59All righty.

4:00Oh, and you know what?

4:01We need one more interface.

4:03I just realized that this interface

4:04right here, R3, that is the 10.38 network, which

4:09is not part of EIGRP yet.

4:10Let's go in and add that.

4:12So we'll go back to the CLI, and let's go to R3.

4:15And let's do a show ip eigrp interface.

4:20Yep, didn't get it.

4:20So we'll config t, and we'll do a router eigrp 1,

4:26and we'll do network 10.38.

4:32And that should pick it up.

4:33If we get a neighborship, which we just did, that's fantastic.

4:36That implies we enabled all the correct interface that

4:39goes down to R8.

4:40So what we have now is we have OSPF on the top and EIGRP

4:45on the bottom, and R3 and R4 are running both routing protocols.

4:49So to do redistribution, we need to pick a router that's

4:51running both routing protocols.

4:53And let's go to R3, and let's take the OSPF routes

4:56and put them in EIGRP.

4:58So to do that, we're going to go into router config for EIGRP,

5:01and then do a redistribute OSPF, and we'll

5:03specify what we want the metrics to be once those routes in OSPF

5:07come into EIGRP.

5:09Let's do that right now.

5:11So on R3, we'll do a show IP protocols,

5:12just to make sure we're on the right device.

5:14It's got OSPF running, great.

5:16It's got EIGRP running.

5:17We'll go into router configuration mode,

5:20or router eigrp 1.

5:21And we'll say, redistribute.

5:23I want to bring in.

5:24I'm pulling in the routes from OSPF.

5:26And it's going to ask me for some questions,

5:28like which process ID?

5:29Process ID 1.

5:29It's going to ask me, what do you want to use for the metric?

5:32Now, if you press Enter here, unless you specified a seed

5:37metric, what the default metric should be,

5:39we're going to have some problems.

5:40As far as troubleshooting, you'd better make sure

5:43that we've either set the defaults that way we wanted to,

5:45or we specify them here for when those routes are brought in.

5:48So let's go ahead and use some context-sensitive help.

5:50And let's say the metric we want to use is--

5:53first all, there's really two that really matter

5:55with the default K values.

5:57And the two that matter are the bandwidth, and also the delay.

6:01We just used OSPF1.

6:03I want to use a metric for these newly-imported routes.

6:05I'm going to put in 100.

6:06Well, if I put in 100, that looks

6:09like a really bad bandwidth.

6:10But I don't care.

6:11We want the route to show up.

6:13It's not going to show up as, really, a great metric,

6:15but that's OK.

6:16It's going to be unique.

6:17So OSPF1 metric, let's do 100 kilobits per second,

6:21and then we'll specify a delay.

6:23Let's go ahead and use 200-microsecond delay.

6:26And then, for the rest, reliability, nobody cares--

6:29I shouldn't say nobody cares about that.

6:31But we're not looking at that for our metric calculations.

6:34So I'm going to put a 1 there.

6:36And then, for the effective bandwidth metric,

6:38I'm going to put a 1 there, because we don't pay attention

6:39that, either.

6:40And a question mark.

6:41The EIGRP MTU, nobody cares about that either.

6:44[LAUGHS] And then, here is where we could actually use a route

6:48map to manipulate and control the routes that

6:51are going to be coming in from OSPF and stuck into EIGRP.

6:55So if we wanted to specify a route map here and then call

6:58upon a route map, we could.

7:00We can also do a match, and then do a question mark.

7:03And then it's saying, OK, regarding

7:05pulling OSPF routes in, do you want

7:07to pull in external or internal?

7:09So this would be a great option here control-wise, to say,

7:12you know what?

7:13Any external routes that came into OSPF,

7:15I don't want to bring them in.

7:17Now, if you do, you could just go ahead and include it.

7:19So these are some of the controls we have

7:21when we do redistribution.

7:22So I'm going to leave that off, not

7:24going to use those controls, and boom, we've got redistribution.

7:27Like, whoa, that was quick.

7:29So if we take a look at our routers--

7:30let's go pick on a router somewhere down here,

7:32like R5, R7, R6, R8.

7:35They're all going to know about these 10.0 networks

7:38up here because R3 is redistributing them into EIGRP.

7:41So let's go take a look.

7:43So back to-- let's go to arr--

7:45let's get R7.

7:46Arr, I'm a pirate--

7:48Arr-7.

7:49And let's do a show IP route.

7:51And we'll just do EIGRP learned routes.

7:54And check it out, we've got some externals,

7:56and externals with a really super high metric.

7:59That's because we didn't give it great bandwidth as far as

8:02when we imported them.

8:03So they're showing up as external EIGRP routes.

8:06The administrator distance for an external EIGRP route is 170.

8:09And we have reachability.

8:12So should we be able to ping 1.1.1.1?

8:16Yeah, the answer to that question is, yeah,

8:19we should be able to ping them.

8:20And I believe that's working.

8:21But the problem is, R1 has no clue how to get back because R1

8:27doesn't have a route to R7.

8:29R7's are just slow.

8:30So let's do a ping, a 1.1.1.1.

8:33This will loopback on R1, and we'll

8:35source it from loopback 0, which is 7.7.7.

8:38And just to confirm, R1 doesn't have a route back.

8:42So if we go back to R1, we say, hey, Mr. R1, show ip route

8:46everything, show me everything, it says,

8:48I don't have a route to 7.7.7.7.

8:51It's just not in my routing table

8:52because no one is sharing with us.

8:54So let's go back and finish our redistribution.

8:56Now, in a production environment,

8:59it would make a lot of sense, short of using when we're

9:03in routing domain, but it would also make a lot of sense,

9:05if we're doing redistribution on R3 of OSPF in EIGRP,

9:10it would be a great idea to do redistribution of EIGRP

9:15back into OSPF on that same device.

9:18Because then you're going to avoid loops, and problems,

9:21and issues.

9:22But the other challenge is that if you do it

9:25just on one device, and that router goes down or has

9:27a problem you'll lose connectivity between the two

9:30routing domains.

9:31So even though we could do it here,

9:33we could do it bi-directional, mutual redistribution here

9:36on R3, we could also do mutual redistribution on R4.

9:40For fun-- and it will be fun--

9:43let's do redistribution of EIGRP into OSPF,

9:48but we'll do it on R4.

9:49And we're going to have very similar controls

9:51as we bring those routes in.

9:53Based on the routing protocols, the metric for EIGRP

9:55is way different than OSPF.

9:57So we're going to have to specify

9:58what we want the seed metric or the basic metric

10:00to be when those routes come in.

10:02So let's go ahead and do redistribution on R4

10:04and take a look at a few of the controls

10:06we can use there as well.

10:08So on R4-- we'll get on the right device--

10:10we'll do a quick show IP protocols

10:14to verify that we are running OSPF and EIGRP.

10:17And we want to pull--

10:18redistribute, like pull the routes from EIGRP into OSPF.

10:23So to do that, we'll go to OSPF--

10:25router ospf 1.

10:26Now, if you're using address families,

10:28the syntax is to be slightly different, again,

10:30based on EIGRP named with address families or OSPF

10:34version 3 with address families.

10:36So the syntax may vary a little bit

10:38based on the version and the method you're using,

10:40but the concept is very similar.

10:42That is, we can control the details

10:44for the newly-injected routes based on the device doing

10:48the redistribution.

10:49So router ospf, we want to redistribute.

10:51And look at this.

10:52There is lots of options here where

10:53we can pull in routes from.

10:55But we're going to pull in routes, in this example,

10:57from eigrp, we're telling the system 1,

10:59and let's use context-sensitive help.

11:01Now it's saying, OK, do you want to use a route

11:03map in association with this, with a route map that

11:05can further define what we're going to pull in

11:09and, as we pull routes in, if we want to manipulate them further

11:13via the set statements in the route map?

11:14So there's lots of options here.

11:16There's also an option for tagging.

11:17If we want to tag those routes as--

11:19let's do 999.

11:20That way, we could filter on those on R3 if we needed to,

11:24or we could look for those routes in the routing table

11:26with the tag of 999.

11:28So let's tag it here.

11:29We could also tag with a route map.

11:31So a route map could be applied, and a route map could match

11:33and then tag also.

11:35So there's more than just one way of doing it.

11:37And let's set the metric.

11:38Let's set the metric.

11:40This is going to be the OSPF metric for routes

11:42that are redistributed in.

11:43Let's set the metric to--

11:45let's do 44, because this is R4 bringing them in.

11:48So we have a metric of 44.

11:49So the routes will show up with a metric of 44.

11:51And what type of metric do you want to use?

11:54With the OSPF, externals have two types-- type 1,

11:57an extra external type 1, which the metric grows

12:00as that route is being propagated through the OSPF

12:02domain, or a type 2, which is fixed.

12:05[GRUNTS] This is the route.

12:07Let's use let's use the metric type of 2 as an example here.

12:14And then we could, again, apply a route map,

12:17which would further manipulate or look at the routes

12:19that we're considering for redistribution

12:21and then manipulate them with whatever

12:23we set in the route map.

12:24And then, let's also includes subnets.

12:26That's a little thing with OSPF.

12:28By default, when you bring in routes,

12:30unless you include the keyword "subnets,"

12:32it's not going to include any subnets.

12:34It's just classful boundaries, which

12:36isn't going to serve our purpose here.

12:38All right, so I included the word "subnets."

12:39And not going to use a route map.

12:41I don't need NSSA only.

12:43So I'm ging to press Enter.

12:45And now we are redistributing EIGRP routes into OSPF.

12:50So if we go to one of these routers-- so this is our four

12:52we just did the redistribution on.

12:54If we go to R1 or R2 and ask them their opinion

12:56about these networks down here, like the 10.78,

13:00or the 10.1 networks on the left,

13:02or the 10.2 networks on the right, let's go take a look

13:05and see what their opinion is.

13:07So we'll go to R1.

13:08And on R1, we'll do a show IP route.

13:14And look at this.

13:14OK, so let me go ahead and actually clean this up a little

13:17bit.

13:18Let's show ip route for ospf run routes.

13:22There we go-- a little less output there.

13:25So here are some examples of routes, so external type 2.

13:29Why?

13:30Because that's what we told R4 to do.

13:31We told R4 to go ahead and use an external type 2.

13:35And there is our metric that we specified the cost--

13:3844, hard coded it.

13:40So if we had multiple devices doing redistribution,

13:44and we wanted one path to be preferred,

13:46how could we do that?

13:47Well, if they're all E2s, and one router, when

13:50it does redistribution, says, hey, the metric is 33,

13:53and one says, the metric is 44, if both routes are available,

13:58it's going to choose the one with the lower cost.

14:01And that's how we can influence which path the traffic

14:03is going to take.

14:05Now, a couple of things that I think are very interesting.

14:09Why is R1 thinking that to reach 5.5.5.5,

14:12which is a loopback, it has two paths, through 13.3 and 13.2?

14:17That's R3 and R2.

14:19Let's take a look at our topology.

14:21That's wack-a-doodle.

14:22So the fun begins.

14:26So R1 says, to get to this loopback,

14:28so R4 is doing the redistribution, and R1 says,

14:31I can go here and here.

14:32It's equal cost.

14:33But this is fast ethernet, and this is all gig,

14:36so those are not really equal costs.

14:39And I just realized what we did-- what I did.

14:41By default, the auto cost reference bandwidth

14:43is 100, meaning that the Fast Ethernet and the gig

14:47look like a cost of 1.

14:49So if we change the cost reference bandwidth

14:51on all our OSPF devices to 1,000,

14:53that would make the gig look like a cost of 1

14:55and the Fast Ethernet look like a cost of 10.

14:58And then it would choose a better path.

15:00Again, that's just OSPF on its own without the redistribution.

15:04So we might want to modify that on a production network

15:07to make sure we're choosing optimal paths.

15:08But that's why that's happening.

15:11Oh, you know what?

15:12In a separate video, as part of this all these sets of videos

15:15and the encore at NRC, we talked about preference,

15:19OSPF preference, where, if it's running the same route,

15:22it's going to use the intra-area route first.

15:25And if there's an inter-area route, it would,

15:29if there's no intra- and there's an inter-area route,

15:32it would use that.

15:33And then, if there is no inter-area route,

15:37it would then start using the E's in the N's.

15:39And we have a whole separate video on that.

15:41But I think what would be interesting to do

15:43is, we did redistribution here.

15:45It's currently R1 is seeing 5.5.5 as an E2.

15:49What if we also did redistribution here on R3

15:54and we used a worse metric?

15:56Like right now, we have a metric of 44.

15:58If we used a worst metric, but we brought it

16:00in as an E1, OSPF preference-wise,

16:04it's going to choose the E1 over the E2.

16:07And we can actually see that.

16:08That's why labbing this up is very helpful and useful

16:12in gaining the skills in both implementing

16:14and troubleshooting routing by looking at the behaviors,

16:17seeing the results, and verifying them

16:19with your own hands.

16:20So let's look to redistribution from EIGRP into OSPF also

16:25on R3, but we'll set them up as type 1s

16:28for the external routes.

16:29And we'll see that R1 will change its attitude,

16:32because it prefers external type 1's with the same exact network

16:36over external type 2's.

16:38So back we go.

16:39And let's go to R3.

16:42And let's go to router ospf 1.

16:44And we'll do a redistribute.

16:46And we're going to redistribute eigrp into--

16:50and the autonomous system number is 1.

16:52And the metric, let's go ahead and set a really bad metric.

16:55So for the metric, let's use--

16:59so for the metric, for these EIGRP

17:01routes that are going to be pumped into OSPF,

17:03let's use a metric of--

17:06let's see here.

17:06How about 88888?

17:08That's a really bad metric.

17:10[LAUGHS] Because everything else in our routing table on R1--

17:14in fact, let's go take a peek.

17:16We have OSPF routes with metric 44, and 2 for the cost.

17:21So 8888 is going to be really high.

17:24OK, then we're going to specify the metric type.

17:27And we're going to bring it in as a metric type of type

17:301, which is preferred over a metric type of type 2

17:33in OSPF, even though the cost is higher.

17:36That's the preference method.

17:37So here, we could go ahead and tag it,

17:39if we want tag the routes that we're bringing in.

17:42Let's tag it with an 8888.

17:44It's just going to be associated with the routes,

17:46so that later, if we need to on another router,

17:48we can say, hey, anything with a tag of 8888 read as special.

17:51Or, don't redistribute it back into EIGRP,

17:53or something to that effect.

17:55And then, include the word "subnet."

17:58That's good, too, because otherwise, the subnets

18:00won't come in.

18:00It will only do classful boundaries.

18:02All right, and we are done.

18:03So now we have redistribution here,

18:06if we do a show IP protocols, we are now

18:09doing mutual redistribution here on R3.

18:12If we do a show IP protocols, so for OSPF1 on R3, it says,

18:15OK, I'm bringing in the routes from EIGRP,

18:19which makes this device an ASPR for OSPF,

18:21bringing in something external, redistributing into OSPF.

18:24And it has the metric.

18:26It says, including subnets.

18:28There's the EIGRP process number.

18:30And if we go download it further and look at EIGRP1, it also--

18:35let me go ahead and scroll up just a little bit--

18:38it also says, hey, I'm redistributing ospf 1

18:41into eigrp.

18:43And so now, if we go to R1, it was just a moment ago

18:46the 5.5.5 network was reachable with the cost of 44.

18:50We had two paths, R2 and R3, because

18:53of our autocost reference bandwidth settings.

18:55But now that R3 is also advertising

18:58that same route for 5.5.5.5, and it's an external type 1--

19:03check this out.

19:04We'll do a show ip route ospf.

19:06And look at this.

19:08There's our external type 1.

19:09There's our crazy high metric.

19:11An external type 1 grows as it propagates through the network.

19:14And so even though the cost is higher,

19:18OSPF prefers intra-area routes than inter-area routes.

19:23Then it goes on to the external on the NSSAs,

19:25and it prefers the E1 over the E2,

19:28even though the metric is higher.

19:30So that's just good to be aware of as far as

19:32how OSPF behaves and operates.

19:34So now, if we want to test connectivity,

19:36we could do a test, we could do a ping

19:38to 7.7.7.7, which is R7 on the bottom left-hand side,

19:43and source it from loopback 0.

19:46And we have full connectivity because we're

19:47doing mutual redistribution.

19:49Oh, and also, before we go, let's do a real quick show IP

19:52route, and let's pick on 7.7.7.7.

19:55And look at that.

19:56This tag, we added that during the redistribution.

19:59So the key is, during redistribution,

20:00we have a lot of control as far as what the metrics are going

20:03to be for those redistricted routes, what rules we're going

20:06to bring in or not bring in, including using a route

20:08map to control that, what gets in and what doesn't get in.

20:11We can control tagging, the type of metric we're using

20:14based on the routing protocol.

20:16So if you were watching this on a mobile device,

20:18I would encourage you to schedule a little bit of time

20:20to go on a computer to the CBT Nuggets website,

20:22click on the link for the virtual lab,

20:24and practice these yourself.

20:25Because the more you practice hands-on

20:27with the redistribution, the more opportunities

20:29you'll have to both be able to configure it

20:31and troubleshoot it in a production environment

20:33should the need arise.

20:34So I'll see you in the next video.

20:36Meanwhile, I hope this has been informative for you,

20:38and I'd like to thank you for viewing.

0:04Imagine if we had two different paths

0:06that we could take to go to a theater, or to dinner,

0:09or whatever it is.

0:10And on these two paths, we'd get notified that, oh, this path is

0:13going to take 10 minutes, and this path

0:15is going to take an hour.

0:16We are going to avoid the path that takes an hour.

0:18Now, we can influence a router to think

0:21a path is really bad by increasing the metric using

0:24a method called an offset list, which

0:27is what we're going to both implement and verify

0:29in this hands-on lab.

0:31So here's our game plan.

0:32Let's toss in eigrp on this topology.

0:36And then we'll take a look at some routes from R8.

0:39And we'll see-- we'll pick a route.

0:41Pick a route, any route.

0:43And we'll identify which path that R8

0:45is using to get to that network-- whether it's

0:46choosing door number one, door number two, or door

0:49number three.

0:50And then we can take that preferred path,

0:52and what we can do is create an offset list.

0:54And here's how an offset list works.

0:56We can say, Dear Mr. Router 8, when you receive--

1:00and we can actually identify a single route

1:03or a list of routes by using an access control

1:05list to point to the exact routes

1:07that we want to manipulate the offset for, the metric for,

1:10or we can use 0.

1:11So if you 0 instead of an actual access control list,

1:15it'll say, OK, that means all routes.

1:17And then, we can also associate with an interface.

1:20So if-- let's just say for a moment that 3 slash 2

1:22is the preferred path to get to a network.

1:25We can specify in eigrp that we're

1:27going to use an offset list.

1:28We can increase the metric by, say, 100 million.

1:33Well, we could also look at the topology table

1:36and see what we would have to be worse than for another route

1:39to be used and simply increase it.

1:41So the offset list increases the metric

1:44by whatever value we specify, and that can thereby

1:47influence the router to no longer take that path that

1:50takes like an hour.

1:50It's going to use a faster path or a quicker path.

1:53But that's yet another tool.

1:54So let's do this.

1:55In the lab environment, click on the link for the virtual lab.

1:58We'll implement eigrp on this topology.

2:00That will take just a few moments.

2:01And then we'll identify the best path R8's taking.

2:04And then we'll manipulate that with an offset list

2:07locally on R8.

2:09And for eigrp everywhere, it's just config t.

2:12Router eigrp.

2:14We'll use autonomous system one.

2:16And also, we have other videos on name mode

2:18and numbered mode for eigrp, so enjoy those videos as well.

2:21And we'll just dump everything in.

2:23So we'll do a Control-A to select all that, right-click,

2:25Copy, and then we'll just go ahead and plug it in on each

2:28of these routers--

2:29just clicking on the tab, right-clicking to paste,

2:31and it is done.

2:32One thing about eigrp, man, is it's so darn fast.

2:36All right, so we have full connectivity right now.

2:40So iproute eigrp.

2:42It looks like we're using Serial3/2 a lot.

2:45Let's go ahead and pick 5.5.5.5.

2:48That'll be a nice one we can pick out and identify.

2:50So to get to 5.5.5.5, it's using Serial3/2.

2:53So if we look at our topology, that's right here.

2:56So for 5.5.5.5, it's going to use Serial3/2

2:59as its egress interface.

3:01And let's go ahead, and we could do an access control list

3:04to specifically call out 5.5.5.5, or we could just say,

3:08hey, any routes that we [INAUDIBLE] in on Serial3/2,

3:11we want to increase the cost, set the offset

3:15to a greater number.

3:17Or we could say on Serial3/2, any updates we receive there,

3:20just go ahead and let's offset that metric

3:22by some number that'll make that path no longer desirable.

3:26And we can also verify that before we do it

3:28by looking at the eigrp topology table, which

3:31will be a good exercise, too, in this lab.

3:33So let's go to R8, and let's take a look at it.

3:37So here on R8, we'll do a show ip eigrp topology.

3:40[LAUGHS] All right, and let's go ahead and put in 5.5.5.5/32.

3:49So as we decode this for this specific route,

3:51there is our current metric, which is--

3:53I'm going to put commas in here so I can read it--

3:55it is 2,298,112, and that is this bad boy.

4:01So this is our successful route.

4:02There's the reported distance from our neighbor.

4:05And here is our feasible successor right here.

4:07Well, at the moment it's a feasible successor

4:09because the advertised distance is

4:11lower than the current feasible distance.

4:13So currently, it's a feasible successor.

4:15Great, and wow, look at this.

4:18[LAUGHS] Its current metric, its current distance to get to 555,

4:24is--

4:25it's going to put the commas in here--

4:27is 40,672,000.

4:3040 million versus 2 million--

4:33holy schneikers.

4:35The reason I point that out is because when we do the offset,

4:38we need to grow it by about 2 million versus 40.

4:43So if we grow it by 38 million, will that be enough?

4:53Actually, let's just grow it by 39 million.

4:56All right, so what we'll do is we'll set offset.

4:58We'll create an offset list, and we'll increase the metric

5:01by 39 million.

5:04So it's going to make this route, this path,

5:07look worse than this guy.

5:08And this guy will take over as the successor route.

5:11All right, I wouldn't have guessed

5:12it was going to be that high, but I'm glad that we looked.

5:14Also, it's a great way to help troubleshoot

5:17by looking at the details of the metrics involved.

5:19All right, let's go ahead and do it.

5:22So here on R8, let's config t.

5:26Instead of using an access control list

5:28to say which specific network, I'm

5:30going to go ahead and say all networks coming in

5:32on interface Serial3/2 right there.

5:36All right, so we'll go and do a router, eigrp,

5:39autonomous-system 1, and press Enter.

5:42And then we'll do an offset list.

5:45And this is where we can specify an ACL to identify which routes

5:49are going to have this offset.

5:51I'm going to use a 0, which is a shortcut for Select All

5:55Networks and it says right here.

5:57And then we'll go ahead and put it in our offset.

5:59So this is going to be for traffic or updates that

6:01are coming in, and we're going to specify the offset of, what

6:06did we say 39 million, 39?

6:071, 2, 3, 1, 2, 3.

6:09All right, and that should do.

6:11[LAUGHS]

6:12We have an update here.

6:13We have our eigrp neighbors, which is fine.

6:16And let's scroll up to find the original route.

6:20So we're looking at 5.5.5.5.

6:22This is before.

6:23It was using Serial3/2.

6:25But now that metric of 2,298,000 is no longer

6:30going to be that, because we bumped it up

6:32by like 39 million.

6:35And so if we do, if we hit the Up Arrow key a couple of times

6:38and do a Show IP Route for eigrp,

6:41and we look at the 5.5.5 network again, and--

6:45oh, my gosh.

6:46[LAUGHS] It's still using Serial3/2.

6:49That's because I did not--

6:51I said, hey!

6:52That's why we had the neighborship messages

6:54with all of our neighbors.

6:55So basically, I increased by 39 million

6:58every single update coming in.

7:01I need to go correct that, because this is not

7:03the results that we wanted.

7:04So we'll do a config t router eigrp, autonomous-system 1.

7:07Hit the Up arrow key a few times.

7:09We'll do a Control-A and say no, offset list 0.

7:12Then we'll go ahead and do that command again.

7:15But this time, we will include the interface,

7:17which is going to be serial 3--

7:19and then let me get the right interface here.

7:21Let me go back here for a moment, our drawing.

7:24It's going to be 3/2.

7:26So only the updates coming in on 3/2

7:29will have that offset applied.

7:32And let's go ahead, and 3/2--

7:35all right.

7:35So Serial3/2 is not going to be too preferred anymore.

7:38Let's show IP route, and let's go ahead and do for--

7:42this [INAUDIBLE] show IP route eigrp.

7:44And let's look for the five network.

7:46And there we go.

7:47There's the five network.

7:48It's now using egress interface of FastEthernet 4/1

7:52with an [INAUDIBLE] of 0.6 because the other route

7:55looks terrible.

7:56So we can verify that with a show IP eigrp topology.

8:00And there it is right there.

8:01It shows us that we have a successor,

8:03and there's this metric, and that's out 4/1.

8:05[LAUGHS] And here is 3/1, which is a feasible successor

8:11because the advertised distance is

8:12less than the actual current successor cost.

8:17And [LAUGHS] our route through 3/2

8:21is not even showing up anymore.

8:23Let's do this.

8:23Let's do a show eigrp topology, and let's do an All Links

8:27option and press Enter.

8:29Now let's look for 5.5.5.5 again.

8:32So there it is.

8:33Even though it's not a feasible successor anymore, now,

8:36with the All Links option, it's going to show up right there.

8:38So there's our winner, there is our feasible successor,

8:41and there is the route that we just

8:43toasted based on setting the offset so stinking high

8:46for that interface.

8:47Another command, while we're here, is a show eigrp topology.

8:51This is a cool one, too.

8:52And that is 0--

8:550 successors.

8:56Show me the eigrp topology database

9:00where there's no winning eigrp route.

9:03And here we go.

9:04These two networks, 10.38.0.1, and also 10.78.0.8.

9:09And it says the FD is infinity.

9:11Well, the metric right here, it doesn't look like infinite

9:14to me.

9:15It looks like a really large number, like 41 million

9:17or whatever.

9:17But what happens here is that if we have a route with a better

9:21AD, like a directly connected network with an AD of 0,

9:26they're going to beat out these routes.

9:28And that's what's happening.

9:29So this is on R8.

9:30It is directly connected to the 10.38.0 network.

9:32It's also directly connected to the 10.78.0 network.

9:35And that's why these routes, with the FD as infinity,

9:38they are not successor routes.

9:40There's no successor route from the eigrp

9:42because their AD isn't good enough

9:43to compete with the directly connected network, which

9:46has an AD of 0.

9:48So in this video, we've had some fun

9:50with playing with another tool that we

9:51can use to manipulate routing, and that is

9:53the concept of an offset list.

9:55We can apply it to an interface.

9:57We can include whether or not it's inbound or outbound

9:59when we modify the offset.

10:01We can also specify with an access control

10:03list which routes it would apply to, specifically

10:06regarding that offset.

10:07Thank you for joining me in this video regarding offset lists

10:10in a Cisco environment, and I'll see you in the next video.

10:12Meanwhile, I hope this has been informative for you,

10:14and I'd like to thank you for viewing.

0:04If we're doing redistribution, and we

0:06want to do like four or five different things

0:08to a specific route, like maybe set

0:09the metric type or the metric itself or tag it,

0:13instead of doing all those individually,

0:15we can also use the method of route map.

0:17So in this video and hands on lab,

0:19I'd like to walk you through a scenario of what

0:21we'd like to do.

0:22We'd include all those details inside of a route map

0:25and then attach that route map to the redistribution

0:28to see it all happen.

0:29Let's take a look at our topology.

0:30And for the demonstration for the lab,

0:32let's just do redistribution from EIGRP,

0:35including the 78 network and the 38 network

0:37and so forth into OSPF.

0:39But instead of specifying all the details

0:42for the metric and the metric type,

0:43what we could do during the redistribution

0:45is call upon a route map.

0:49In that route map, we could match on one or more

0:52of our routes with a match statement,

0:55and then based on it matching, we could go ahead and do set.

0:58We could set things like a tag.

0:59We could set things like the metric type.

1:02We can set things like the actual metric

1:04that those rules will get as they're brought into OSPF,

1:07and for routers one and two, we'll just bring all the routes

1:10in for OSPF.

1:13So router OSPF 1, and then we'll do a network in area 0.

1:20So that last set of four zeros right there, that'll be

1:23flipped to 255s as a wildcard mask.

1:26This is a quicker way of implementing it,

1:28and we'll do that on R1 and R2.

1:30So we'll copy all that, right-click copy,

1:32and then we'll go ahead and go to R1,

1:34paste it in, R2, paste it in.

1:36And let's take a look at R3 and 4.

1:38Now, R3 and 4, we don't want everything brought in.

1:40But R3 and R4, we want 10.0 dot anything.

1:44So we'll go ahead and implement that with a 0.0.255.255.

1:50And that'll be great for R3 and R4.

1:52Also, on R3 and R4, we'll need EIGRP,

1:54so let's also add that right here, the router EIGRP,

1:58autonomous system one, and we'll do network 10.1 and also

2:06network 10.2, and that'll be appropriate for R3 and R4.

2:14That's great.

2:15We'll do a control A.

2:16Oh, also, you know what?

2:18For R3's benefit, we'll need network 10.38 as well.

2:26That's the link from R3 that goes down to R8.

2:30All right.

2:31And we'll do a control A, grab all that, right-click, copy,

2:35and we'll get R3, paste it in, R4, paste it in.

2:39And then let's do the rest of the routers, 5, 6, 7,

2:418 with all EIGRP on everything.

2:43So we'll go to config t, and we'll

2:46do router EIGRP, autonomous system one, net zero, zero,

2:52zero, zero, and we're done.

2:54That'll be on routers 5, 6, 7, and 8.

2:56So copy that and then router 5, router 6, router 7,

3:02and router 8.

3:04Then we could spot check the interfaces, as well.

3:06So if we go to R3, and let's take a look at our topology

3:08together.

3:09So on R3, you should have gig 10 and FA 4/0 in OSPF.

3:13Those are 10.0 networks.

3:14And FA 4/1 should be in EIGRP.

3:17Let's verify that real quick, as well.

3:20So here on router 3, we'll just show IP OSPF interface brief.

3:25And sure enough, we have 0.

3:270, which was in our topology, but 10 and FA 4/0

3:30all running OSPF, show IP EIGRP interface.

3:36And that should be FA 4/1 and 3/2.

3:40And that is FA 4/1 and 3/2.

3:42Let's take a look at my topology again.

3:44Oh, yeah.

3:443/2 goes down to R8, and that is in EIGRP, as well.

3:48Fantastic.

3:49All right.

3:49So let's see if we have any route maps to begin.

3:51We'll do show route map.

3:53Great.

3:53No route map, so we'll go ahead and create one,

3:56and I'm going to use all caps here.

3:57So let's go ahead and call it EIGRP number 2 OSPF.

4:02So that's the name or route map.

4:03Now, in the route map, if we just pressed enter,

4:06this route map sequence would be given a sequence number

4:09automatically, and it'd also be a permit.

4:11But if you want to be explicit, we

4:12could go ahead and explicitly put both the permit, as well as

4:16the sequence number right here, which is what I'm going to do.

4:19I'm going to say permit, and then I'll

4:21go ahead and say sequence number 10 and a question mark,

4:24and we'll press enter.

4:25So we're now in sequence number 10,

4:27and now we have to do our if-then.

4:29And let's start--

4:29Oh, you know what?

4:31Let's go out just for a moment.

4:32Let's create an access control list

4:34that points to the 7777 32-bit route,

4:37so access-- because we're going to need to point to that.

4:40So access list one, and we'll say permit,

4:43and we'll say 7.7.7.7 with a 32-bit mask.

4:48Awesome.

4:48Now that exists, I'm going to go back into that exact sequence

4:52number of this route map.

4:54So route map, the name, and then permit, sequence 10.

4:57We're right back in that sequence number.

5:01So now I'm going to do a match.

5:03And we'll do a match.

5:04There's lots of things that we can match on,

5:06including a lot of attributes based on the protocol

5:08that we're using.

5:09In this case, we're going to match on IP and address,

5:14and we are going to match on axis list number one.

5:17That's the one we just created that's looking

5:19for the exact 32-bit route 7.7.7.7.

5:22We'll put one here, space, and a question mark.

5:25Now this is where, if we had four or five access lists,

5:29we can specify access list one, access list nine,

5:31access list 20.

5:33And if they're all in the same line, It's an or.

5:36So any one of those access list being matched as a yes, this

5:40matches, that line would be considered true.

5:43So in this case, we're going to match

5:45for just one access list, access list one, and let's also--

5:49let's match and a question mark, and let's do route type,

5:55and let's specify internal.

6:00And we'll press enter.

6:01So now we do a do show route map.

6:04Let's see we have so far.

6:06We've got a route map called EIGRP to OSPF.

6:10We have one sequence number so far, 10.

6:12In that sequence, we're matching an IP address,

6:15matching access list one,s and also matching on route type

6:18internal.

6:18Now because those match statements

6:20are in two different lines, they both have

6:21to be true in order for this set, which we're about to put

6:24in, to go ahead and take place.

6:27So on multiple lines, all those conditions

6:29in the matches on multiple lines have

6:30to have one true element on each of the lines

6:33or the whole result of that sequence to be considered true.

6:37So let's continue.

6:38Let's go ahead and, based on those two conditions

6:40being true, let's do a set and a question mark.

6:42[LAUGHS] And there's lots of options that we can set here.

6:46Let's go ahead and set the metric,

6:48and we'll set the initial seed metric to 30

6:51based on this route map being activated and matching,

6:54and let's also do a set metric type

6:58of type one, which is the external type

7:00one once it gets into OSPF.

7:02That is the metric type that will continue

7:04to grow as that route is propagated and advertised

7:06further and further away, as opposed to a type two

7:09for OSPF, which just stays fixed.

7:11OK.

7:12So let's do show command again, do show route map,

7:15and let's see what we have.

7:16So if the route matches access list one,

7:18which is the 7.7.7.7 network, and if it's an internal route,

7:22we're going to go ahead, and we are

7:24going to set the metric to 30.

7:25We are going to set the metric type to type one,

7:27and, hey, while we're at it, let's also set a tag.

7:30Let's set the tag to 90, which is the AD for EIGRP

7:37for internal routes.

7:38But if we want to look for that tag,

7:40it'll show up in OSPF with any routes that have been brought

7:42in, and we'll press enter.

7:44Now, one other thing here is with a route map,

7:46is that this route map has one sequence number that's

7:49a permit.

7:50So what's going to happen if we apply this route map as part

7:53of our redistribution from EIGRP going into OSPF,

7:57it's going to go down to sequence 10.

7:59It's going to say, OK.

8:00Match.

8:00It's going to look for the route of 7.7.7.7,

8:04and that it's an internal route, and then it's

8:06going to set those parameters, the metric, the metric type,

8:09and also the tag.

8:10And any route that isn't 7.7.7.7 and isn't

8:14internal, both those things, it will go ahead and deny.

8:18So it's sort of like an access control list

8:19used for filtering on an interface in the sense

8:21that it's going to process the sequence numbers from top

8:24to bottom, like lines top to bottom,

8:25and if it doesn't find the match,

8:27it just says, sorry, it's not happening.

8:29So with this by itself, the only route

8:32that is going to be redistributed into OSPF

8:35is going to bee the 7.7.7.7 network because everything

8:38else is denied.

8:39So let's verify that that happens, and then

8:40we'll go back, and we'll tweak the route

8:42map to have it be a little bit more

8:43lenient with the sequence number 20.

8:45So now we have the route map, let's apply it.

8:48So we'll go into router OSPF 1, and then

8:51we're going to redistribute EIGRP routes into OSPF

8:54and tag on that route map, so the syntax

8:58would be redistribute, and we're pulling in EIGRP

9:02from autonomous system one, and we'll use a question mark.

9:05And we're going to include subnets, yes,

9:07and here's where we can also specify the route map.

9:10So we'll do a route map, and then

9:12the name of our route map--

9:13I'm going to scroll up a little bit so I don't do a typo.

9:15It's right here.

9:18So let's highlight that and paste it

9:19in, space, and so the metric and the metric type and the tag

9:24are all going to be done in the route map.

9:26It's like pre-baked, ready to go, and we'll press enter.

9:31Now, how do we verify that?

9:33How do we troubleshoot this?

9:34If we're having trouble with the redistribution

9:36not happening the way we think it should,

9:38I would first check the route map.

9:39Show route map, and take a look at what we're looking for based

9:45on the matches and the sets.

9:47Also we'll do a show IP OSPF, and that's

9:52going to show us details, including

9:53redistributing external routes from the EIGRP one.

9:57Fantastic.

9:57So we're doing the redistribution.

9:59So if we go up to R1, whose up in OSPF land,

10:03so here's the topology.

10:05Now, we did the redistribution here on R3.

10:07Let's go to R1 and take a look at the routes.

10:09If we did it correctly, all we should have is,

10:12as far as an external OSPF route perspective, is one route.

10:16And that is 7.7.7.7 that was redistributed in

10:20and including the attributes the route map set for it.

10:23So let's go ahead and go to R1 right here.

10:26Let's do a show IP route and press enter.

10:31And there it is, but, whaoa, we have more route.

10:34Hmm.

10:35Did I not call on the ACL?

10:36Let's go take a look at that.

10:38So there's these 7.7.7.7 network.

10:41There's the route itself, and if we did a show IP

10:44route for 7.7.7.7.

10:50We should have details, including

10:51the tag, so it's there, but so are other routes.

10:55So let's go back and check our route map, do show route map.

11:00And this says access list one.

11:03Let's go take a look at it and type, internal,

11:09and let's take a look at the access list.

11:14Oh, permit any.

11:15[LAUGHS] A little too lenient.

11:19I don't remember doing that, but I'm sure I did,

11:21so troubleshooting route maps, which is part of our objective

11:24here, is to make sure the individual components are

11:27correct.

11:27So let's fix that.

11:29I'm not sure how I did that.

11:31We'll do a no access list one and then access list one,

11:38and we'll permit, and we'll do 7.7.7.7.

11:42We can also put a host in front of there,

11:43but by default, it's going to think that's a 32-bit match.

11:46Do show access list.

11:50OK.

11:51And let's do this, too.

11:51Let's do a clear IP route, asterisk, nice fresh start

11:55for everything.

11:57And let's go back up to R1, who a moment ago was getting

12:02all these external routes, all these EIGRP

12:04routes because the access control list said,

12:06everything's good.

12:07But now we do a show IP route, and I'll

12:10do a show IP route for everything.

12:13Now it's much better.

12:14We have one route.

12:16That's the 7.7.7.7, and it is an external type one,

12:20and it has all those attributes that we set on that route

12:23in the actual route map.

12:25But one other thing we can do is this.

12:28If we went back to the route map, show--

12:30on the right router.

12:31Let's go back to R3 and do a show route map.

12:36So there it is.

12:37If we wanted to add another sequence number, we could--

12:41anything that didn't match sequence 10, which

12:43is the internal type and the specific IP address specified

12:47by the access control list, we could go ahead,

12:49for all the other routes that didn't match sequence 10,

12:51we could put another entry in and have

12:53a whole other set of matching requirements

12:55and then set requirements.

12:57So let's modify that a little bit.

12:58We'll do config t and route map, and we'll put in the same name

13:02here.

13:05Now, by default, if I don't do anything else,

13:07it'll be a permit.

13:08It'll also auto sequence it for me.

13:10It'll give me a sequence line, probably of 20,

13:13so we'll do a do show route map.

13:15Always verify what we think happened.

13:18So I don't see another sequence number there.

13:21Hmm.

13:22Let me go ahead and do a show route map again,

13:25and look at that.

13:26All right.

13:27Well, that's good know.

13:28I'm glad I checked.

13:28So I'm going to go ahead and write that again,

13:31route map EIGRP to OSPF.

13:34I'll say permit explicitly, and I'm

13:35going to give it sequence number 20.

13:38And now we'll do a show route map.

13:40There we go.

13:41So there's our sequence 20.

13:43Now, sequence 20 has no match conditions in it whatsoever.

13:47What that means, if there's no match, it simply says, great.

13:50Everything matches, and there's no considerations as far

13:53as qualifying for a match in that sequence.

13:55So if we wanted to bring in all the routes from EIGRP,

13:59the first sequence number would get

14:00internal routes that match the ACL and do the metric type

14:04and everything else that's specified.

14:06And then the rest that didn't match

14:08that would hit sequence 20, match there, and then just be

14:10brought in as normal.

14:12What we could do, though-- let's do a set,

14:14and let's do a set tag of--

14:18let's do a set tag of 333, and that way,

14:21what we should see is that the network 7.7.7.7 will have

14:24the tag of 90 and all the rest of the EIGRP routes

14:27that were brought in, because the sequence 20 that doesn't

14:30have a match condition, would automatically

14:32get the tag of 3.3.3.3.

14:35So let's go back up to R1, and on R1,

14:39let's do a show IP route, and here

14:41we have a whole bunch of additional routes,

14:43but by default, it brought him in as an external type

14:46two because we didn't specify.

14:48And if we did a show IP route for one

14:50of those specific routes, there's our tag of 3.3.3.3.

14:54So in this video, we've taken a look

14:56at an example on the syntax and logic of a route map

14:59that can have a whole bunch of pre-baked if-then statements,

15:02there are match and set statements,

15:04and then we can include those route maps

15:06as part of our redistribution to control

15:08what we want to come in, how we want it to be marked,

15:11which gives us the ability to control those attributes when

15:14those routes are being redistributed.

15:15So thanks for joining me in this video and lab,

15:17and I'll see you in the next video.

15:19Meanwhile, I hope this has been informative for you,

15:21and I'd like to thank you for viewing.

0:05There are situations where the default for a given routing

0:07protocol are going to help protect us,

0:09so that we don't even need to get creative with modifying

0:12the administrative distance, or filtering routes, or tagging

0:15routes, or looking for that tag.

0:16So in this video, I'd like to chat with you about some

0:19of those defaults that are really going to help us right

0:20out of the gate.

0:21Also, remind us of a few of the tools

0:23we can use regarding tagging and filtering,

0:25and also touch on the concept of split horizon, which

0:29in some situations can bite us as well.

0:32So let's take a look at the topology,

0:33and let's review those concepts together.

0:36So let's imagine we have routing domain A right here,

0:41and routing domain, including this network, B. And then--

0:48or let me include him here also.

0:50And then routing domain C right here.

0:53One of the key things when [CHUCKLES]

0:55first of all, designing a network,

0:56is, you'd never want to design a network intentionally this way,

0:59where you'd have to do redistribution.

1:01It'd be much easier and simpler to run one routing domain.

1:03Let's start there.

1:04But as far as redistribution goes,

1:06if we have routes like the 12 network in routing domain A,

1:09and we're redistributing that into routing domain B,

1:12and then B is redistributing into routing

1:14domain C, what we'd want to do is make sure that we're not

1:18redistributing that route, the 12 route,

1:21back into routing domain A.

1:23Or a network in routing domain B to get put into C,

1:27we want to make sure that it doesn't get redistributed back

1:29into B. So we have AD that we can play with.

1:32Like in a GRP, the administrative distance

1:34for internal is a better AD than it is for externals.

1:37It's 90 and 170.

1:39But we can also manipulate the administrative distance

1:41for a given routing protocol on a specific router,

1:44and we say, hey, dear Mr. R6, you're

1:46going to believe that the administrative distance

1:48for OSPF is 89, and make it better or more believable.

1:53So that's a fairly graceful solution.

1:55But we could also-- if we needed to, we could also do tagging,

1:58and you could do tagging on the redistribution

2:00with or without a route map.

2:01And so you could tag all the routes that were redistributed,

2:04and then identify those with another route map

2:06before you redistribute it again.

2:08So that way, we can control, on redistribution

2:10for the match, what can be redistributed.

2:13We can look for or deny a certain tag,

2:15and that can also control whether or not

2:17a route will be redistributed.

2:18Along with that route map, of course,

2:20we can set the attributes appropriate for that

2:22routing protocol as well.

2:24So tagging is certainly an option that we can use,

2:26or bringing a route in, tagging it,

2:29and we can look for that tag later, and give

2:30that specific route either another redistribution

2:34or no redistribution, based on the tags that it has.

2:36That does take a little bit more planning, [CHUCKLES]

2:39but it is certainly doable, as far as routes

2:41that are going to be redistributed in,

2:43and then also as we redistribute them, what

2:45tag they are going to be given.

2:47Also, a really good key is to focus on one network at a time.

2:50So if we have the 12 network, for example, up here, or the 78

2:53network, it's important to follow that network's progress

2:56through the network.

2:57And so as you do your redistribution,

2:59and if you identify, whoa, that route 78 is not

3:03showing up here at all, then we can identify why.

3:05OK, R4 is doing redistribution from B

3:08to A. That route got into B. Why isn't it picking up?

3:11And each routing protocol behaves a little bit

3:14differently based on the types of route,

3:16and did that route get into the routing table.

3:19And that's why some hands-on practice

3:20in doing the redistribution, looking at the results,

3:23and then having tools like offset lists, and distribute

3:26lists, and route maps, can be very helpful in controlling

3:30the traffic.

3:31Because at the end of the day, we want optimal paths

3:33through the network, and if the routing protocol or a bunch

3:36of routing protocols that are glued together

3:38with redistribution is not causing that to happen,

3:40that's when you start going in and adding

3:42additional techniques, and go ahead

3:44and make certain routes appear better than other routes,

3:46or doing additional filtering so that optimal paths are

3:49taken in the network.

3:51And if we simply need to make a route look worse,

3:53we could use a condition called route poisoning.

3:56And poisoning, from a general concept,

3:58is making it look worse.

4:00So we did that with offset lists,

4:02and with the offset list on R8, I

4:04believe we attached it to serial 3/2,

4:06so that any routes that were being learned on that interface

4:09would automatically have an additional offset or made

4:11to look worse, and that is a form of poisoning.

4:15There is also situations, like in DMVPN, if we are

4:18using Dynamic Multipoint VPN--

4:20which we have another set of videos

4:22here in this course on-- but with DMVPN, we have a hub

4:27and we have spokes.

4:28Here's spoke 1 and spoke 2.

4:30And because we're coming into a single multipoint interface,

4:34split horizon, which is built in to the route-- like RIP has it,

4:38and GRP has it on by default. If router 1 advertises the route

4:42and it comes in on this interface,

4:44split horizon says, "Oh, I'm not going

4:46to advertise the route out on the same interface I learned it

4:48on."

4:49So it doesn't send it down here.

4:50However, in DMVPN, we need to turn off that feature.

4:54So that's in the DMVPN videos, where we go to that interface,

4:57and tell it not to use split horizon,

4:58because we do want a route that's

5:00advertised by spoke 1, that goes up to the hub,

5:03to be advertised back out that same logical multipoint tunnel

5:06interface, and be sent down to the [CHUCKLES] site 2,

5:10right there, so it can actually learn the route.

5:12So it's important to realize some of those behaviors

5:14and the defaults for the various routing protocols

5:17so that when we're implementing them,

5:19and our routes don't show up like we expect them to,

5:21we can go ahead and correct it by tweaking those defaults,

5:24in this case, by tweaking the split horizon

5:26rule on the multipoint interface at the hub.

5:29And well, another one to think about,

5:31one other trick that we can do with administrative distances,

5:34if we have some routes up here in this routing domain A,

5:37and we've got some from EIGRP which are external,

5:42and we have others that are EIGRP internal, by default,

5:46the administrative distance is going

5:47to be 170 for the external and 90 for the internal.

5:51And if we want to change those, we can.

5:54[CHUCKLES] We can manipulate the administrative distance

5:57for all external EIGRP-learned routes,

5:59or for a specific route, or we can

6:01change the administrative distance for a specific route

6:04learned from a specific neighbor.

6:06So we have an administrative distance that we can tweak.

6:08This is an EIGRP example.

6:10But that is yet another way to choose which route would

6:13be used when there's multiple routes presented, simply

6:16by going in and specifying, hey, this administrative distance

6:19is going to be 70 or 60.

6:21And that will make that route show up in the routing table,

6:23and then start to be used if we need it to be used,

6:25for optional padding in our network.

6:27So in this set of videos, we've had the opportunity

6:29to add some additional tools to our tool belt

6:32as far as manipulating and controlling routing behavior

6:35on a Cisco device.

6:36So I'm glad you joined me.

6:37I'll see you in the next video.

6:38Meanwhile, I hope this has been informative for you,

6:40and I'd like to thank you for viewing.