Hello everyone, this is your host Habib's a career from catechol IPS computing solutions. I am the Network Solutions Architect and I have been doing consultancy for small to large organizations and I have been providing Network Solutions. And I'm happy to present to you the topic of today, which is filtering routes using prefix list. Now, as you know, we can filter routes using access lists. prefix list is a much more powerful method for taking out routes that are unwanted from the routers. And also it helps to maintain your routing table and by cleaning it.

It's been used in many occasions, even internet providers use it too. Clear out malicious routes. And basically maintain the routing topology of the networks prefix which have been useful in this case. Now in this lecture I'll be presenting this topology plus four different cases where we will simulate different types of networks. This process will be giving you hands on plus step by step demonstration of how to do an apply prefix list in an organization. So please join me for for this course, in this course and we will we will examine different classes of routes and block those routes from the routing table or basically remove them from the routing table.

So let's go ahead and start and take it from here. In our first lecture here, we will The topology Yeah, so let's bring up these routers, we will create Point to Point connectivity between r three to r one and r two. We will make sure the networks will be will be up and running and we will we will go from here. So, let's continue. First we will bring up our three and we will we will activate the interfaces and the loopback addresses just to simulate those networks that I have mentioned. Our three just came up as you can see.

So first of all, what we will do is not that our three is up and running, we will configure the link between r three and r one and we will give it the network of 192 dot 168 dot 10 network. And we will also configure We will also give the link between r one and r two the 170 to 230 network we will give it a slash 30 subnet mask so, we only need to host IP addresses from here and we will configure two IP addresses by giving it slash 30 we know that we only have two available host addresses. So for each interface on the routers, okay, so a little bit of basically what we will do is we will bring show IP interface brief and just see if interfaces are still down, just examine the routers properly and we will continue from here. Count T is to come to the first interfaces interface FA zero slash zero.

We'll assign it the IP address 192 dot six c 168 dot 10 dot 125 525-525-5252 no shot We'll also create a series of loopback interfaces here. IP address, interface loopback zero, give it an IP address of 10 dot one dot 121 2.5255255 dot zero. The loopback address comes up automatically you don't have to exit it, mode interface loopback one, give it 10 dot one dot two dot 1255255255 dot 128 interface ello to right now. All right p address 10 dot one dot three dot one 2.5255255 dot 192. Let's go to the other interface interface loopback three let's give it another IP address 10 dot one dot four dot 125525525224. Let's create another loopback interface loopback interface for IP address 20 dot dot zero dot zero dot 1255 dot zero dot two They're only told zero.

That's exit. Now we will build a routing table by introducing a dynamic routing protocol. We'll use the protocol the eigrp and the process 10. Now network zero dot zero dot zero dot zero is used to advertise all connected networks and we will apply no auto summary and exit. Let's save the topology. Let's see the IP interface brief.

Now we are done with our three as you can see all the interfaces are up. Yeah so now we will move on to our One while it's coming up, we'll move on. I will like to talk about prefix list. prefix list was actually introduced in Cisco routers. It was introduced in iOS version 12 and up when it was introduced it was it. The main purpose was to filter routes you by using the prefix list of the networks, just basically the subnet mask of the networks.

So yeah, we can use the subnet mask to our advantage. When it comes to prefix lists. prefix lists actually process the process the prefix using sequence numbers from from top to bottom. So if you don't do sequence numbers, they can still be, they will still the routers will still process them from top to bottom. Just like the access list, they also have denial statement at the end. That's pretty much about prefix lists.

It's not really so complicated. It's it has a little bit of, you know, complexity when it comes to, you know, defining the networks. But it's not complicated. Once you practice and you see how it works. It's easy to catch up, and, and you'll be able to learn how to do it. One more important thing is actually you don't need to know the host names like access list, because you're basically filtering the network.

Based on their prefixes, which is the subnet mask, and that takes care of most of the network. Okay, so we brought up our one I'm just taking show IP interface brief just to list the interfaces in our one. We will be configuring the F 00 interface. We'll give it an IP address, which is the second host IP address of the network. We chose 192 168 dot dot 10 dot 225 525-525-5252 which is a slash 30. No shot Yeah, sweet.

Campaign the interface dot one, which is basically our 3d interface. Yeah, so let's now add another interface as well which is F Zero slash one. That interface is basically the interface that connects to our two. And we'll keep it network again which is a point to point network as we discussed it's gonna be in the range of 170 to 230. Network. Now it could be anything but we will appear choosing 172 30 zero dot 125 525-525-5252 no shots we will introduce the router Ei GRP.

P 10 network zero dot zero dot zero dot zero no auto summary as you can see it has already found adjacency with with router r three. Now we will do the same thing with r two as well, the same process that we followed. So so are our two is up now so let's do show IP interface brief and we will we will assign the the IP for the interface F Zero slash one So interface F Zero slash one IP address 172 30 dot zero dot 2255255 2.52 52 sorry, slash 30 at work and we'll say no sharps. Same thing as we did in our three we will also do the loopback interfaces, just to simulate different types of networks coming from from the start to end. So in our case, there is a set of networks that's coming from our two as well as set of networks that are coming in advertised from our three and interface loopback zero IP address.

One seven 216 dot 10 dot 125525525520 interface loopback 01 IP address 172 dot 16 dot 11 dot 12552 552-552-2224 interface loopback IP address 172 dot 16 dot 13 dot 1255255255 dot 248 Let's choose 248 interface loopback four IP address 172 dot 16 dot 11 dot 1255255255 dot 192 I'm getting an overlap. Oh, that's because we already assigned network elevens somewhere else. So let's choose top 14 interface loopback zero IP address 129 dot 10 dot 16 dot one 2.5255 dot zero dot zero. Let's add one more interface loopback six IP address 130 dot 10 dot 16 dot 125525520 dot zero exit. Let's save it now. Now let's add router Ei GRP 10 network zero dot zero dot zero dot zero no shut no to summary sorry, exit exit show IP interface brief just to see all the interfaces are up they have six loopback addresses you can see there's a synchronization has happening and the network is getting fully converged.

So in our next session we will look at the routing tables.