1. Introduction
In this section you’ll learn about rip and EIGRP. It’s actually OSPF, which is the main focus of the CCNA exam as far as routing protocols are concerned. But you are still expected to know the fundamentals of rip and EIGRP, so we’re going to cover them here. You’re not going to need to know how to configure, but I’m going to show you in this section anyway because I always find it’s much easier to understand something if you can see how it is configured. I’ll also get into some of the more advanced rip and EIGRP topics as well, such as passive interfaces, default route injection, and wild card masks because they also apply to OSPF and seeing how they work across how all the different routing protocols is going to give you a greater understanding of them. Okay, let’s get into it.
2. RIP the Routing Information Protocol
This lecture you’ll learn about rip, the routing information protocol. Rip is a distance vector routing protocol. We spoke earlier about the difference between distance vector and link state routing protocols. So you know that it’s distance vector. So it’s going to be using routing by rumor. It uses hopkinc as its metric. So let’s say the router one wants to get to the ten one O network, and to get there it needs to go via r two, r three, and R four. Then that network would be three hops away. A hop is a router that the traffic has to go through to get to that final destination.
The maximum hop count is 15. So there’s a bit of a scalability limitation with rip, so it’s not really used except in lab or demo environments. It will perform equal cost multi path up to four equal cost paths by default. We are currently on rip version two. Before that, obviously was rip version one. Rip version one is a legacy protocol, which is typically not used at all anymore. Rip version two isn’t used very often. Rip version one really isn’t used at all anymore, although it is still supported on Cisco routers. Rip version one had limitations even worse than we have with rip version two. It doesn’t send subnet mask information with routing updates, so variable amp subnet masks VLSM is not supported. Now you don’t have to use classful networks with rip version one.
For example, all of your networks could be a slash 28, and that would work just fine as long as they’re all 28. But you couldn’t have some 24, some 28, and some 30, for example. They all have to be the same. Rip version two does support VLSM. Rip version one. Updates are sent every 30 seconds as broadcast traffic, so everything that gets hit by the traffic in that subnet has to process it. Rip version two uses multicast address two, two, four, or nine, so it’s more efficient than rip version one is and rip version two supports authentication. Rip version one does not. With authentication, we can put a password on the router on both sides of the link, so they will not form an adjacency unless they both have the same matching password. It gives us some better security. Authentication is supported in all the modern routing protocols. It’s not covered on the CCNA exam two. We also have ripng as well as rip version one and rip version two. Rip ng is rip next generation that supports IPV six networks. It’s not covered on the CCNA exam. So for the current version of CCNA, you really only need to know rip version two to configure rip. Pretty simple. At global config, we say router rip and then optionally we’re going to say version two.
We do want it to be running the latest version, and then to specify the interfaces that you want rip to be running on and to be advertised, we use the network command. So in this example, we’ve said network ten o. All interfaces that begin with ten will start sending out rip hello messages and trying to form an adjacency. When they do form a peering relationship with a router on the other side of the link, they will advertise all of the ten networks to that router. The network command should reference a class phone network and no subnet mask is specified. So for example, if on the router we had an interface with IP address ten 1124, we don’t say network ten 10, we say network ten o.
Rip will automatically summarize routes to the class full boundary by default. For example, if you’ve got an interface with IP address 19216 810 130 and under Rip you include that with a network statement. It will be advertised as 19216 810 24 because any address that begins with 192 is a class C address which has got a default mask of 24. So in an example, rather than advertising it as a slash 30, it will summarize it to a 24. If we had an interface with IP address 170 216 ten 130, that would be advertised as one 7216 O 16 because that’s a Class B address and it would default to a 16 that is almost never desirable. Unless, by some magical coincidence, your network, the summarization, does fall exactly in the class four boundaries, in which case it would be fine. Your network modern view networks aren’t designed that they all fall the summarization ranges exactly on class four boundaries.
So if you leave Auto Summary turned on, it’s liable. It caused havoc on your network, possibly black holing, dropping some of your traffic. So we always disable auto summary. To do that. The command is router rip and then no Auto Summary. So we don’t want to do the automatic summarization, but we probably still will want to do summarization manually. To do that. The command is IP Summary address. So we would do this to get control of exactly how we are summarizing. When we do this, the individual summarized routes that fall within the larger range are not going to be advertised, only the summary route. So in the neighbor router that learns the route, it’s not going to learn all those different individual routes, it will only learn the summary route. So it’s more efficient, it takes up less memory.
It also compartmentalizes the different parts of your network. So if you have an outage anywhere, it’s going to limit the impact that that has network wide. So to configure this, well, looking at an example here on router R Two, you see that all of the ten one networks are over to the left out interface fast 10. All of the ten O networks are over to the right out interface fast zero on router R Two. So what we’re going to do in the example is R Two is going to advertise all of the ten dot or networks to r Three as a single summary route. So rather than advertising ten or 24 and 100, it’s just going to advertise ten o 16. So R Three is only going to learn that one summary route rather than the three individual 24 routes. So we can figure this at the interface level and you configure it on the interface that you’re sending the summary route out of. So all of the 100 networks are available out interface fast zero. But we’re going to advertise that to R Three out interface fast 10. So we configure this on interface fast 10, the interface we’re sending the summary out of and then to configure the summary, we say IP summary address Rip ten o and then the subnet mask 255255 or so it will just send that one route of ten o 16 to routerr three. To be honest though, Rip is only used in really small networks or for labs or for demos.
So your network is probably not going to be that big that you’re going to care too much about summarization anyway to verify Rip, to verify any routing protocol that we’ve got running on a router, we can say show IP protocols. So we’ve done that in the example here and we can see that the routing protocol was Rip. Rip is running. I can also see the interfaces that Rip is running on. So it’s running on fast 01020 and 30. And I must have just put this command in not long after configuring it because it’s only sent and received two updates on those interfaces. I can see it will do equal cost to load balancing up to four maximum paths. It’s routing for the ten or network and it’s got neighbors routing information sources at 100 two and 100 three two.
And the distance is the administrative distance, which defaults to 124 Rip. If I wanted to see my Rip configuration, I can do a show run and then pipe and then section Rip. Rather than doing a show run and having to scroll through the whole config to the Rip section, this will show me just a Rip command. So it’s quite convenient. And once I’ve configured Rip, I’m going to want to check that I do have Rip routes in the routing table. So my standard command for that is show IP route. In the example here, I can see that I’ve got four routes that were learned via Rip. I can see that by on the column in the left it says R means they were learned by Rip. And I can see that the administrative distance is 120.
And then I’ve got the slash after that is the metric, that is how many hop counts that destination network is away, the next hop address when I received the last update and the outgoing interface. And finally I can also check the Rip database. What this is useful for is if you’ve configured Rip and then you can see that you’ve got rip neighbors. But you look in the routing table and you’re not seeing the expected routes in there. Well, maybe the routes weren’t even received at all. So the way that you can check that is with the Show IP database.
Or maybe the routes were received, but they’re not the best route. So to check if the routes were received at all by rip, whether or not they made it into the routing table or not, we can do a Show IP rip database. Next thing to cover here is default route injection. This is where we have got a default static route for all traffic, probably going out to the Internet. And we don’t want to have to configure a default static route on every single router. So what we’ll do is on the final outbound router, which is connected out to the Internet, we will configure a default static route there, and we will then advertise it, inject it into rip, so all of our other internal routers will learn about it automatically. Saves us having to do a static route for on every single router in the organization. So in the example here, it’s R four that is connected to the Internet. So on. R four, I say IP Route Zero.
So it’s a default static route with a next hop address of 203 1132. I then want to inject that into rip. So I say router rip and default information originate so that default static route will be injected into rip, and it will be advertised to R Three and R Five from R four. And then they will advertise it on further inbound into my other internal rip routers if I now do a Show IP route. So this was on R one. If I go back to the topology diagram, you see that R One is all the way over on the right. It will have learned this because I configured it on R four. And on R one, I do have a rip route for zero zero.
So it’s a default static route. The administrative distance is 120 because it’s rip, the hop count is two, and I can see that my next hop address is 100. Three two out interface fast ethernet 30. Okay, that was everything I needed to tell you about rip here. I’ll see you in the next lecture for a lab demo of a basic grip configuration.
3. RIP Lab Demo
In this lecture, you’ll learn how to configure and verify Rip with a lab demo. So I’ve got the lab topology open here. We’ve got five routers, R One to R five, and you can see that all of the interfaces begin with a ten, apart from this interface on R Four interface Fast 30, which is going out to the Internet. We’ll configure that one a little bit later. So for now, let’s configure all of the internal networks that all start with ten. So I’m going to configure that on all of the different routers. Actually, before I do that, let’s just check and see that there’s no routing protocols running on here already. So I’ll do a Show IP protocols and you can see there’s no routing protocols running.
And if I do a Show IP route, it’s just the connected and the local routes. So I want to configure Rip and all of the different routers. It’s going to be the same commands on each one. So rather than typing it in on each router each time, I’m going to use WordPad and I’m going to copy and paste from there. So let’s go to WordPad and the commands are router rip. I’m going to run version two. I want to do no auto summary. I don’t want to do automatic summarization at the class full boundaries, and it’s going to be network ten or on each router. Actually, let’s do a config t at the start to save me typing that in each time, and I will copy and paste this into each router.
So I’ll start on r one, then R two, R three, r four and R five. And it will take a minute or so for the routers to converge. So let’s just check the Show IP protocols first. And this is on R five. I can see that Rip is running now and it’s routing for the 100 networks. And if I do a Show IP route, let’s see if we’ve got Rip routes in the routing table yet. Yes, we do. I can see my connected to my local routes, and on R five, I can see routes for the ten one networks and individual routes for all of the different 100 networks as well. If I go back to the topology diagram on R One, I should see connected and local routes for the 100 networks and routes learned via Rip for the ten one networks.
So let’s verify that. I’ll do a Show IP route on R One, and I can see I’ve got all of those individual ten one networks learned through Rip in the routing table. I can see that the administrative distance is 120, which is the standard ad for Rip, and I can see how many hops away it is as well. Going back to the topology diagram again, I should have a route for the ten 1224 network. I could go along the top path, but that would be one, two, three hops or the bottom path, which is only two hops. So it’s going to go out the bottom path out interface fast 30. And the next hop address should be 100 three two with a hop count of two. So let’s verify that. And I can see there’s learn through rip there’s the ten 1224 network. The hopcount is two and it’s via R five at 100 three two out the fast Ethernet 30 interface. So that was a basic configuration for Rip. I’ve now got reachability between all of my different internal networks. The next thing I’ll configure is summarization because you can see on our one here that we’ve got all of the individual ten one networks listed separately.
If I have a look back at the topology diagram, I can see that all of the ten one networks are available through either R two or R five. So an r two and r five. I’ll configure summarization. I will summarize it to rather than the individual ten one Xx 24, I’ll summarize it to ten. We do that on the interface that we’re advertising the summary right out of. So on fast zero on R two and fast 30 on R five, I’ll do that summary ten one O 16 route. I also want to do summarization in the opposite direction as well. So you can see that all of the 100 X networks are available out the right hand side on R two and R five. So I interface fast 10 and R two and fast 20 and R five.
I’ll advertise those as a summary address of ten O 16 and that will go to R three and R four. So let’s do that on R two first. So I’ll jump onto its command line and the right hand side interface on R two was interface fast zero. This is the one that’s facing R one and I want to advertise the ten one networks out this interface. So the command is IP summary address. I’ll use tab completion for that. It’s for the Rip protocol. And that was the ten one O networks and I’ll advertise it as a 16. So that’s 255-2550 in the opposite direction that was on interface fast 10 and IP summary address ripteno 25 two five five. So that is R two done. I also need to do R five. So I’ll go to global configuration on R five. The interface facing R one is interfacefast 30 and I want to do IP summary address rip the ten 10 networks 255-2550 and in the other direction it was interface fast two slash zero which is facing over to the left. And that’s going to be IP summary address rip ten 025-5255. Okay, so that’s my summary routes configured on R two and R five. So let’s check. This is working now. So I’ll go back onto R one and what I’ll do is I’m going to restart Rip here. Normally in a production environment, you wouldn’t want to do that obviously, because you would lose your route. You would just wait for rip to reconverge. But that can take a few minutes. So to speed things up here, I’ll say configtee and I’ll do a no router rip, and then router rip version two, no auto summary and network ten.
So I just restarted rip there just to force it to converge immediately. And now if I do a show IP route, you see that rather than having all those individual ten one x 24 networks, I’ve got a route for ten individual networks are now removed from the routing table. If we go back to the topology diagram, you see that when I did a summary route on r two and r five. Well, it’s one hop from r one to both of those. So that’s an equal cost. It’s an equal hop count, which is a rip metric. So both of those go into the routing table, and r one will do equal cost load balancing over both of them. So that’s why you can see for ten one six, I’ve got two routes which have both got a hop count of one. One is going out fast, 30 to ten three two, which is on r five. The other one is out fast, zero to 100 two, which is r two. Okay, so that was our summarization configured. Last thing I want to do is to give internet connectivity everywhere. So on r four, we’ve got a connection out to the service provider at 2030 113 two. So on r four, I will add a default static route going out to the service provider, and I’ll then inject that into rip so that all of my other routers learn about it. So let’s go on to our four. And I want to do an IP route for zero zero. So it’s a default static route, and the next top address was two three dot o, dot one one three dot two at the service provider. Now, I could go on to all of my other routers and also configure a static default route and all of those as well.
But to save me all that admin work, instead I’ll inject it into rip on our four. So the command to do that is router rip and then default information originate, and that will inject it into rip. And if I go back onto r one again, and I’ll just restart rip on here again. So let me copy my config, go back onto r one, config t I’ll do a no router rip and then restart rip again. I must have not copied that correctly. I’ll just type it in. Okay, so router rip, version two, no auto summary, network, ten o. And then if I do a show IP route, it still needs to have gone through the other routers as well. So let’s see if it’s showing up yet. And there I can see it’s in rip. I’ve got a default static route, and it’s going to the next top of ten three two, which is on R Five interface fast 30.
If I also look at R Two and do a Show IP route there as well, I can also see that that default route has been propagated throughout my network. One last thing that I want to do is let’s say that I want my routers to have a route to that 203 network. Let’s go back to the topology diagram. So say I want all of my other routers to have a route to the 203 one one three network. That’s not happening right now because I didn’t have a network statement configured for that on R Four. So we’ll add that with a network statement. But I don’t want to advertise my internal network information out to the service provider. So I’m going to make interfacefast 30 and R Four a passive interface. So that’s the last thing to do. So let’s go on to R Four again. And under router rip, I will say passive interface fast, and it was 30 and then network 203 0113.
That’s done now. And let’s go back onto R One again. And you see that previously I did not have a route for the 203 network on R One. It might not have converged yet. So let’s do the same again. Let’s restart rip. So no router rip. Router rip version two, no auto summary without a Typo network, ten o. And if I do a Show IP route now, hopefully there’s my route for the 203 o network. But the service provider router won’t learn any of our internal routes because if I go back to the topology diagram again on Fast 30 and R Four, I made that a passive interface. So R Four is not going to advertise any rip routes out of that interface. Okay, that was it. That was our rip configuration and verification. I’ll see you in the next section where we’ll move on to EIGRP.
