Implementing Cisco IP Routing (642-902 ROUTE) Tutorials
Route Redistribution / Lab 2 - Filtering Routes and Admin Distance
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Subtitles of the Movie (Implementing Cisco IP Routing (642-902 ROUTE) / Route Redistribution / Lab 2 - Filtering Routes and Admin Distance)
So we're picking up right where we left off. We have modified our Route Map from OSPF into EIGRP. We've set a Deny Statement to match this tag so that routes are not Redistributed in a huge loop. Now we're going to change the OSPF Route Map using the same logic. However, since we have multiple Tags that we're matching here, this Permit or more accurately this Deny Statement here is a little different and it's, it's logical how it's set up but it's still a little different. So we'll do Config T. We will do Route Map EIGRP to OSPF. I'll just copy it from there. We'll do Deny 5. In this case we're going to have multiple arguments with the Match Section. So we'll do Match Tag, in this case we're going to Match Tag 100 or 200 or 500 or 250 and that's a valid argument there. When you set up like this, that's exactly how I set it as I was typing it. Match Tag 100 or 200 or 500 or 250. If you put the Match Statements on separate lines, then that means all of this has to Match at the same time. So if you had Match Tag 100 and then on the next line Match Tag 200, then on the next line Match Tag 500. Then that means whatever route fit this Deny criteria would have to match all of those at the same time and obviously we don't have any routes that match all of the Tags at the same time. It's going to only have one Tag even though a route can have multiple Tags on it, none of our routes do. So we Match Tag 100, 200, 500 or 250 and that's it. It's the same logic that we had with the other Route Map and so now that we've modified our 1, let's go and make the same modifications on R2. So we'll do Show Run Section Route Map, so I just can copy it between the two. So we'll grab this first section here and go over to Router 2 and do Config T, right-click and put those commands in there, go back to Router 1 and grab the same thing for the OSPF Route Map. Exit from here, right-click and put the other one in there and now that we've done this, let's check our Routing Tables to make sure we haven't just broken our network right in half. So we'll go here, we'll do Show IP Routes, we're still getting these EIGRP external routes. We'll go over to Corp 1, let's make sure that we're still getting the OSPF external routes. And we are and they're still Load Balanced exactly as we would expect. So we've moved right along, right down our lab objectives. We're now coming into the home stretch. We've done the first four, now we just have twenty percent of our lab left to do. Luckily it's the simplest part or one of the simplest parts. We're going to manipulate the Administrative Distance. And you'll recall the Administrative Distance is this first number right here, this 170 in this case, because that's the Administrative Distance for external EIGRP routes. So the objective says traffic from Corp 2 should prefer the link between R1 and Corp 1. Adjust Administrative Distances to prefer this link over the link between R2 and Corp 1. So basically what we're saying is and we have traffic that comes from Corp 2, it should go up to R2 over to R1 and then up to Corp 1. It should not just take this shortest link here and there may be several logical reasons for doing that. Let's say that this is a segment that's got a lot of traffic on it so even though this is a longer route around this way, this is still going to be quicker because there's less traffic on this link versus this link. Or maybe we just like this one better, who knows? Or perhaps this is traffic that we're wanting to send through this segment so that a Data Security or a IT Security department can siphon of this traffic and see what's coming from Corp 2. Regardless of the business or technical reason, we have to send all the traffic from Corp 2 out this router. Now Corp 1, where, we don't care how it gets down here to Corp 2, it can take either of these links and in the absence of outside influences it will take the shortest link. It'll go right here to R2 and right out to Corp 2. Now there are other ways you can do this. You can set a Policy Map and a Route Map over here that says when you see traffic coming from here, you, you send it to it's next hop of .1. However the lab doesn't way that we can do that, the objective says that we have to modify the Administrative Distance. So let's talk a little bit about Administrative Distance. Now I'll go over here to router 2, since that's where we're going to have to adjust it anyway. Administrative Distance is this first number that is listed here for each individual route. This is the Metric, obviously 65 is the OSPF Metric that it's learning. This is the Metric for the Redistributed Routes coming in through EIGRP. Now the Administrative Distance is basically how believable our routing protocol is. In this case, if you have two routes, let's say we had two routes to the 10.10.1 network. One that was learned through OSPF and one that was learned through EIGRP. If we had both of these routes here, it would prefer the route learned by EIGRP because it is a more reliable protocol, it's a more believable protocol. So basically if we look at this network over here, we have to adjust the Administrative Distance of router 2 to say external OSPF routes have a lower Administrative Distance than my EIGRP routes that I've learned right here. And that way it will say, well this is the lower Admin Distance, this is the way I'm going to go, this is the route I'm going to put in the Routing Table. So I'm going to go this way and then back over into Corp. Now we'll do that in the next video and we'll verify that it actually did as we expected.
Tutorial Information
| Course: | Implementing Cisco IP Routing (642-902 ROUTE) |
| Author: | Greg Dickinson |
| SKU: | 34291 |
| ISBN: | 978-1-61866-028-2 |
| Release Date: | 2011-12-28 |
| Duration: | 10 hrs / 105 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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